•

1 like•73 views

Connecting distant chips in a quantum network is one of biggest challenges for superconducting quantum computers. Superconducting systems operate at microwave frequencies; transmission of microwave signals through room-temperature quantum channels is impossible due to the omnipresent thermal noise. I will show how two well-known experimental techniques—parity measurements on superconducting systems and optomechanical force sensing—can be combined to generate entanglement between two superconducting qubits through a room-temperature environment. An optomechanical transducer acting as a force sensor can be used to determine the state of a superconducting qubit. A joint readout of two qubits and postselection can lead to entanglement between the qubits. From a conceptual perspective, the transducer senses force exerted by a quantum object, entering a new paradigm in force sensing. In a typical scenario, the force sensed by an optomechanical system is classical. I will argue that the coherence between different states of the qubit (which give rise to different values of the force) can be preserved during the measurement, making it an important resource for quantum communication.

Report

Share

Report

Share

Download to read offline

Novel approaches to optomechanical transduction

Optomechanical systems offer a promising route towards frequency conversion between microwaves and light. Current theoretical and experimental efforts focus on approaches based on either optomechanically induced transparency (suffering from limited conversion bandwidth) or adiabatic passage (requiring time-dependent control). In my talk, I will present two alternative strategies for optomechanical transduction that avoid these limitations. In the first one, entanglement between two superconducting qubits is generated by using transducers as force sensors; jointly measuring the force with which the qubits act on the transducers leads to conditional generation of entanglement between the qubits. The other device uses spatially adiabatic frequency conversion in an array of optomechanical transducers, allowing for large conversion bandwidth with time-independent control.

Hybrid quantum systems

In this tutorial, I will give an overview of hybrid quantum systems and their applications in quantum technologies. I will start by reviewing their individual components, focusing primarily on the theory of superconducting circuits, cavity optomechanics, and electromechanics. Afterwards, I will discuss a few applications of hybrid systems composed of these components. In particular, I will explain how opto-electro-mechanical systems can be used to achieve frequency conversion between microwaves and light and how electromechanical systems can be used to couple mechanical motion to superconducting quantum bits.

Controlling the motion of levitated particles by coherent scattering

Coherent scattering allows for versatile optomechanical interactions that can be used to control the motion of levitated particles. A modulated trapping beam can generate strong mechanical squeezing in both the transient and steady-state regimes. Coherent scattering also enables interactions between multiple levitated particles and is a powerful tool for levitated optomechanics applications such as force sensing and full control of particle motion.

Quantum force sensing with optomechanical transducers

Optomechanical force sensing is an established measurement technique that can reach remarkable precision. In most applications, the system exerting the force on the mechanical oscillator is treated classically and we are not interested in any coherence between states of the system that give rise to different forces. A full quantum treatment, however, enables richer physics since measuring more such systems can lead to interference effects.
In this talk, I will show that the coherence can survive the measurement and can be used for quantum-technological applications. I will consider a model example of spin readout in superconducting qubits. Coupling two transmon qubits to mechanical oscillators and reading out the mechanical positions using a single beam of light provides information on the total spin of the qubits. It is thus possible to conditionally generate entanglement between the two qubits. The system represents a basic quantum network with superconducting circuits. The scheme has modest requirements on the system parameters; it does not require ground-state cooling or resolved-sideband regime and can work with quantum cooperativity moderately larger than unity.
Afterwards, I will consider another scheme, namely nondestructive detection of a single photon using an optomechanical transducer. The basic idea is similar to spin readout; the photon exerts a force on a mechanical oscillator and the the force is measured optically. I will argue that such a measurement is subject to a quantum limit due to backaction of the transducer on the dynamics of the photon and that this result also applies to other techniques of nondestructive photon detection, such as methods using Kerr interaction between the single photon and a meter beam. Finally, I will show numerically that measurement backaction can be evaded when the measurement rate is suitably modulated.

Ancilla-error-transparent swap tests in circuit quantum electrodynamics

This document discusses using Kerr-cat qubits as ancillas for performing swap tests. Kerr-cat qubits are encoded in coherent states of light and are biased towards phase flip errors. The document proposes using a Kerr-cat qubit to implement a controlled-swap gate between two other qubits via a controlled-phase beam splitter interaction. This controlled-swap gate can then be used to perform a swap test between the two qubits while inheriting the Kerr-cat qubit's noise bias towards phase flips. Performing swap tests this way could make them more robust against errors and enable applications like quantum state tomography and phase estimation.

Microwave entanglement created using swap tests with biased noise

Poster presented at the 737th WE Heraeus Seminar Advances in Scalable Hardware Platforms for Quantum Computing

Measurement-induced long-distance entanglement of superconducting qubits usin...

1. The document proposes using optomechanical transducers to entangle superconducting qubits over long distances.
2. An optomechanical transducer can act as a force sensor to measure superconducting qubits coupled to a mechanical oscillator.
3. The mechanical oscillator is modeled using a conditional master equation and can be adiabatically eliminated to obtain an effective equation describing the qubits.

Improved optomechanical interactions for quantum technologies

Cavity optomechanics reached remarkable success in coupling optical and mechanical degrees of freedom. The standard mechanism relies on dispersive interaction wherein a cavity mode acquires a frequency shift proportional to the mechanical displacement. Efficient coupling is, however, often impeded by large cavity decay rates or strong heating of the mechanical element by optical absorption. In this talk, I will present two strategies to circumvent this problem. In the first one, a membrane doped with an ensemble of two-level emitters or patterned with a photonic-crystal structure is used as a mechanical element. The hybridization of the cavity mode with the membrane’s internal resonance leads to a modified response, resulting in an effective narrow cavity linewidth. I will show how such systems can be described quantum mechanically and discuss how optomechanical sideband cooling can be improved by the presence of the internal resonance. Second, I will discuss optomechanics with levitated particles and show how coherent scattering can be used to generate strong mechanical squeezing. In this system, the standard dispersive interaction is replaced by scattering of the trapping beam into an empty cavity mode. This process can result in strong, controllable coupling between the cavity mode and the motion of the particle with minimal absorption heating. I will also briefly outline how this type of interaction can be used to engineer coupling between different center-of-mass modes of the particle allowing, in principle, full optomechanical control of the particle motion.

Novel approaches to optomechanical transduction

Optomechanical systems offer a promising route towards frequency conversion between microwaves and light. Current theoretical and experimental efforts focus on approaches based on either optomechanically induced transparency (suffering from limited conversion bandwidth) or adiabatic passage (requiring time-dependent control). In my talk, I will present two alternative strategies for optomechanical transduction that avoid these limitations. In the first one, entanglement between two superconducting qubits is generated by using transducers as force sensors; jointly measuring the force with which the qubits act on the transducers leads to conditional generation of entanglement between the qubits. The other device uses spatially adiabatic frequency conversion in an array of optomechanical transducers, allowing for large conversion bandwidth with time-independent control.

Hybrid quantum systems

In this tutorial, I will give an overview of hybrid quantum systems and their applications in quantum technologies. I will start by reviewing their individual components, focusing primarily on the theory of superconducting circuits, cavity optomechanics, and electromechanics. Afterwards, I will discuss a few applications of hybrid systems composed of these components. In particular, I will explain how opto-electro-mechanical systems can be used to achieve frequency conversion between microwaves and light and how electromechanical systems can be used to couple mechanical motion to superconducting quantum bits.

Controlling the motion of levitated particles by coherent scattering

Coherent scattering allows for versatile optomechanical interactions that can be used to control the motion of levitated particles. A modulated trapping beam can generate strong mechanical squeezing in both the transient and steady-state regimes. Coherent scattering also enables interactions between multiple levitated particles and is a powerful tool for levitated optomechanics applications such as force sensing and full control of particle motion.

Quantum force sensing with optomechanical transducers

Optomechanical force sensing is an established measurement technique that can reach remarkable precision. In most applications, the system exerting the force on the mechanical oscillator is treated classically and we are not interested in any coherence between states of the system that give rise to different forces. A full quantum treatment, however, enables richer physics since measuring more such systems can lead to interference effects.
In this talk, I will show that the coherence can survive the measurement and can be used for quantum-technological applications. I will consider a model example of spin readout in superconducting qubits. Coupling two transmon qubits to mechanical oscillators and reading out the mechanical positions using a single beam of light provides information on the total spin of the qubits. It is thus possible to conditionally generate entanglement between the two qubits. The system represents a basic quantum network with superconducting circuits. The scheme has modest requirements on the system parameters; it does not require ground-state cooling or resolved-sideband regime and can work with quantum cooperativity moderately larger than unity.
Afterwards, I will consider another scheme, namely nondestructive detection of a single photon using an optomechanical transducer. The basic idea is similar to spin readout; the photon exerts a force on a mechanical oscillator and the the force is measured optically. I will argue that such a measurement is subject to a quantum limit due to backaction of the transducer on the dynamics of the photon and that this result also applies to other techniques of nondestructive photon detection, such as methods using Kerr interaction between the single photon and a meter beam. Finally, I will show numerically that measurement backaction can be evaded when the measurement rate is suitably modulated.

Ancilla-error-transparent swap tests in circuit quantum electrodynamics

This document discusses using Kerr-cat qubits as ancillas for performing swap tests. Kerr-cat qubits are encoded in coherent states of light and are biased towards phase flip errors. The document proposes using a Kerr-cat qubit to implement a controlled-swap gate between two other qubits via a controlled-phase beam splitter interaction. This controlled-swap gate can then be used to perform a swap test between the two qubits while inheriting the Kerr-cat qubit's noise bias towards phase flips. Performing swap tests this way could make them more robust against errors and enable applications like quantum state tomography and phase estimation.

Microwave entanglement created using swap tests with biased noise

Poster presented at the 737th WE Heraeus Seminar Advances in Scalable Hardware Platforms for Quantum Computing

Measurement-induced long-distance entanglement of superconducting qubits usin...

1. The document proposes using optomechanical transducers to entangle superconducting qubits over long distances.
2. An optomechanical transducer can act as a force sensor to measure superconducting qubits coupled to a mechanical oscillator.
3. The mechanical oscillator is modeled using a conditional master equation and can be adiabatically eliminated to obtain an effective equation describing the qubits.

Improved optomechanical interactions for quantum technologies

Cavity optomechanics reached remarkable success in coupling optical and mechanical degrees of freedom. The standard mechanism relies on dispersive interaction wherein a cavity mode acquires a frequency shift proportional to the mechanical displacement. Efficient coupling is, however, often impeded by large cavity decay rates or strong heating of the mechanical element by optical absorption. In this talk, I will present two strategies to circumvent this problem. In the first one, a membrane doped with an ensemble of two-level emitters or patterned with a photonic-crystal structure is used as a mechanical element. The hybridization of the cavity mode with the membrane’s internal resonance leads to a modified response, resulting in an effective narrow cavity linewidth. I will show how such systems can be described quantum mechanically and discuss how optomechanical sideband cooling can be improved by the presence of the internal resonance. Second, I will discuss optomechanics with levitated particles and show how coherent scattering can be used to generate strong mechanical squeezing. In this system, the standard dispersive interaction is replaced by scattering of the trapping beam into an empty cavity mode. This process can result in strong, controllable coupling between the cavity mode and the motion of the particle with minimal absorption heating. I will also briefly outline how this type of interaction can be used to engineer coupling between different center-of-mass modes of the particle allowing, in principle, full optomechanical control of the particle motion.

Measurement-induced long-distance entanglement of superconducting qubits usin...

Although superconducting systems provide a promising platform for quantum computing, their networking poses a challenge as they cannot be interfaced to light---the medium used to send quantum signals through channels at room temperature. We show that mechanical oscillators can mediated such coupling and light can be used to measure the joint state of two distant qubits. The measurement provides information on the total spin of the two qubits such that entangled qubit states can be postselected. Entanglement generation is possible without ground-state cooling of the mechanical oscillators for systems with optomechanical cooperativity moderately larger than unity; in addition, our setup tolerates a substantial transmission loss. The approach is scalable to generation of multipartite entanglement and represents a crucial step towards quantum networks with superconducting circuits.

Iván Brihuega-Probing graphene physics at the atomic scale

Los días 22 y 23 de junio de 2016 organizamos en la Fundación Ramón Areces un simposio internacional sobre 'Materiales bidimensionales: explorando los límites de la física y la ingeniería'. En colaboración con el Massachusetts Institute of Technology (MIT), científicos de este prestigioso centro de investigación mostraron las propiedades únicas de materiales como el grafeno, de solo un átomo de espesor, y al mismo tiempo más resistente que el acero y mucho más ligero.

Search for Neutron Electric Dipole Moment

The document summarizes a proposal for a new neutron electric dipole moment (EDM) experiment at the Spallation Neutron Source (SNS). The experiment aims to improve the current neutron EDM sensitivity by two orders of magnitude using ultra-cold neutrons produced in superfluid helium-4 and polarized helium-3 as a co-magnetometer. Many feasibility studies have been conducted, including tests of the helium-3 spin precession frequency matching technique. Construction of the new neutron EDM experiment is expected to begin in fiscal year 2010 with the goal of reaching a sensitivity of less than 1×10-28 e-cm.

Visit at CERN

The document provides information for a visit to CERN, the European Organization for Nuclear Research. It begins with an agenda for the visit including a presentation and tour of the experimental areas. It then provides statistics on CERN such as its founding date, member states, staff, and budget. The main goals of CERN are explained as pushing the boundaries of knowledge through high-energy particle collisions to better understand the big bang and develop new technologies. Diagrams show CERN's series of larger and more powerful particle accelerators built over time, culminating in the Large Hadron Collider, a 27km ring that smashes protons together. The document describes the LHC's detectors that observe collision data and CERN's worldwide grid network that

Fundamental Processes in
Organic and Hybrid Solar Cells

Invited talk at the LHP15 / Soltech Meeting at Kloster Banz, Germany
- photogeneration in model system for organic solar cells (pBTTT:PCBM)
- charge carrier recombination in phase separated organic blends by kinetic Monte Carlo simulations
- radiative efficiency and electrooptical reciprocity in organic-inorganic perovskite solar cells
- nongeminate

Calculation of isotopic dipole moments with spectroscopic accuracy

Trabalho apresentado no XVII Symposium on High Resolution Molecular Spectroscopy (HighRus-2012), 2012, Zelenogorsk-Russia. Anals of XVII Symposium on High Resolution Molecular Spectroscopy (HighRus-2012), 2012.

NANO266 - Lecture 13 - Ab initio molecular dyanmics

UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.

optics chapter_07_solution_manual

This document contains problems related to simple harmonic motion, forced vibrations, and the origin of refractive index. Problem 7.1 asks the reader to plot the displacement of a string at various points over time given an equation describing the wave. Problem 7.2 asks the reader to analyze the time variation of displacement in loops of a standing wave given another equation. Problem 7.3 asks the reader to show that a mass dropped in a tunnel through the earth would execute simple harmonic motion and calculate the time period. The remaining problems involve calculating various properties related to simple harmonic motion, polarization, dielectric constants, plasma frequencies, and refractive indices.

CUPC Oct 14, 2015

This document discusses modeling magnetic fields of microtrap arrays for trapping ultracold atoms. It describes how double-loop microtraps can be used to create arrays of traps and transfer atoms between adjacent traps by varying currents. Adding an additional Ioffe coil can generate a trap with a nonzero minimum field to prevent atom loss due to spin flips. The microtraps use much smaller currents than macroscopic traps and allow controlling trap position and depth through bias fields, which could enable applications in precision measurements, quantum information processing, and more.

Gupta Roy MS Thesis Defense

This document summarizes a thesis defense that presented a design for an intrinsic coincident polarimeter using stacked organic photovoltaic (OPV) devices. The polarimeter design leverages the polarization-sensitive properties of OPVs to allow for simultaneous measurement of the Stokes parameters that characterize polarized light. The polarimeter model and calibration procedure were validated experimentally. Results showed the polarimeter could predict the intensity of unknown incident light with 2.2% average error and determine normalized Stokes parameters with 1.2% RMS error. Future work proposed extending the design to include circular polarization detection and modifying the OPV structure.

Two efficient algorithms for drawing accurate and beautiful phonon dispersion

Purpose: easy drawing of accurate and beautiful phonon dispersion in first-principles calculations
See also: Draw phonon dispersion of Si with Quantum Espresso https://gist.github.com/t-nissie/32c10a148a7fc054b836

VPrasad_DAEBRNSHEPDec2014talk

1) The document discusses studies of photon detection efficiency and position resolution of the electromagnetic calorimeter (EMC) at the BESIII experiment using control samples of initial state radiation processes.
2) Datasets of J/psi and psi(3770) decays are used to calibrate the EMC energy and position measurements, which are affected by factors like crystal quality and electronic noise.
3) The photon detection efficiency is found to agree between data and Monte Carlo simulation to within 1%, and the EMC position resolution is improved by applying new correction factors derived from calibration samples.

ppt on the Solar cells understanding semiconductor devices

1. The document provides an overview of semiconductor devices including solar cells, LEDs, transistors, and more through a schedule and explanations of key concepts.
2. The core concepts covered include how solar cells work through photovoltaic absorption, charge carrier generation and transport, and collection.
3. Different types of solar cell materials and designs are examined like silicon, CIGS thin films, and multi-junction cells to understand how their properties influence efficiency.

Semi-empirical Monte Carlo optical-gain modelling of Nuclear Imaging scintill...

The document describes a semi-empirical Monte Carlo model to estimate the optical gain (DOG) of single crystal scintillators excited by gamma rays. The model divides the crystal into layers, uses EGSnrc to simulate gamma ray absorption, and combines this with an analytical model of optical photon propagation between layers. The model is validated against experimental data for LSO:Ce, GSO:Ce and YAP:Ce crystals at 140keV and 364keV. Results show the model can predict DOG values and determine an optimum crystal thickness for different gamma ray energies.

Characterization of Carrier Lifetime

This document provides an overview of carrier lifetime characterization techniques. It discusses that carrier lifetime determines the performance of semiconductor devices and solar cells. It then defines recombination lifetime and generation lifetime. The document proceeds to describe various optical methods to measure carrier lifetime, including photoluminescence, free carrier absorption, photoconductance decay, and their advantages and disadvantages. It provides equations to calculate carrier lifetime from measurements of excess carrier density, conductivity change, and voltage change.

27 Double π0 photoproduction on the neutron at GRAAL - Physics Letters B, Jul...

27 Double π0 photoproduction on the neutron at GRAAL - Physics Letters B, Jul...Cristian Randieri PhD

Double π0 photoproduction on the neutron at GRAAL - Physics Letters B, Elsevier, July 2007, Vol. 651, N. 2-3, pp. 108-113, ISSN: 0370-2693, doi: 10.1016/j.physletb.2007.06.009
di J. Ajaka, Y. Assafiri, O. Bartalini, V. Bellini, S. Bouchigny, M. Castoldi, A. D'Angelo, J. P. Didelez, R. Di Salvo, A. Fantini, L. Fichen, G. Gervino, F. Ghio, B. Girolami, A. Giusa, M. Guidal, E. Hourany, R. Kunne, A. Lapik, P. Levi Sandri, D. Moricciani, A. Mushkarenkov, V. Nedorezov, C. Randieri, N. Rudnev, G. Russo, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge (2007)
Abstract
The photoproduction of double π0 on the neutron is studied in the beam energy range of 0.6 up to 1.5 GeV, using a liquid deuterium target. The cross section and the beam asymmetry are extracted and compared to those previously obtained on a proton target. The theoretical interpretation of these results is given using different models.Loss mechanisms in Polymer-Fullerene Solar Cells

(1) The document discusses loss mechanisms in polymer-fullerene solar cells that limit performance.
(2) With additive, nongeminate recombination occurs via free carrier and trap-assisted recombination. Reconstruction works well.
(3) Without additive, incomplete reconstruction is due to voltage-dependent photogeneration from spatial trapping on fullerene islands.

Phase-field modeling of crystal nucleation II: Comparison with simulations an...

This document summarizes phase-field modeling of crystal nucleation. It discusses:
1) Homogeneous nucleation models using the phase-field method and their comparison to molecular dynamics simulations and experiments for systems like nickel and Lennard-Jones argon.
2) Applications of the phase-field model to heterogeneous systems like ice-water nucleation.
3) The effects of different double-well and interpolation functions on nucleation behavior in phase-field models.

giessen short

Atomic and molecular ion merged-beams experiments provide absolute charge transfer cross section measurements from keV/u to meV/u energies. This allows studying charge transfer processes important for fusion plasmas, astrophysics, and other applications. The technique uses intense ion beams merged with atomic hydrogen beams. Recent work includes measurements of charge transfer from highly charged ions like C6+ and O8+ to gases like hydrogen and krypton, observing x-ray emission. Future work aims to study charge transfer reactions of molecular ions like D2+ and CO+ with hydrogen, comparing results to state-to-state calculations. These experiments provide benchmark data to advance understanding of low-energy ion-atom interactions.

Презентация Microsoft PowerPoint

The mass-energy and angular distributions of fragments produced in the 136Xe+208Pb reaction were measured between 423-617 MeV. Low-energy collisions were found to produce neutron-rich nuclei near N=126, with yields exceeding predictions. Multi-nucleon transfer reactions show promise for synthesizing more neutron-rich superheavy nuclei, though beams heavier than 136Xe are needed. Further studies aim to better understand neutron fluxes in astrophysical r-process nucleosynthesis of transuranic elements.

Novel approaches to optomechanical transduction

Slides for a presentation I gave at the Spring meeting of the German Physical Society in Mainz on March 10, 2017.
In the presentation, I discuss new approaches to frequency conversion of electromagnetic fields using optomechanical interaction. The main figure of merit we are trying to optimize is the transduction bandwidth. I show that the bandwidth can be enhanced by using spatially adiabatic state transfer in an array of conventional optomechanical transducers.

Interference effects in cavity optomechanics with hybridized membranes

1) The document discusses interference effects in cavity optomechanics systems with hybridized membranes. It describes how adding two-level systems or gratings to membranes can lead to Fano resonances in the cavity spectrum.
2) A Fano resonance suppresses Stokes scattering and improves cooling of the membrane. Many physical systems could exhibit these interference effects, including photonic crystal membranes, atom arrays, and excitons in semiconductors.
3) Functionalized membranes have applications in cavity optomechanics and cavity QED such as improved cooling and serving as an end mirror with strong coupling.

Measurement-induced long-distance entanglement of superconducting qubits usin...

Although superconducting systems provide a promising platform for quantum computing, their networking poses a challenge as they cannot be interfaced to light---the medium used to send quantum signals through channels at room temperature. We show that mechanical oscillators can mediated such coupling and light can be used to measure the joint state of two distant qubits. The measurement provides information on the total spin of the two qubits such that entangled qubit states can be postselected. Entanglement generation is possible without ground-state cooling of the mechanical oscillators for systems with optomechanical cooperativity moderately larger than unity; in addition, our setup tolerates a substantial transmission loss. The approach is scalable to generation of multipartite entanglement and represents a crucial step towards quantum networks with superconducting circuits.

Iván Brihuega-Probing graphene physics at the atomic scale

Los días 22 y 23 de junio de 2016 organizamos en la Fundación Ramón Areces un simposio internacional sobre 'Materiales bidimensionales: explorando los límites de la física y la ingeniería'. En colaboración con el Massachusetts Institute of Technology (MIT), científicos de este prestigioso centro de investigación mostraron las propiedades únicas de materiales como el grafeno, de solo un átomo de espesor, y al mismo tiempo más resistente que el acero y mucho más ligero.

Search for Neutron Electric Dipole Moment

The document summarizes a proposal for a new neutron electric dipole moment (EDM) experiment at the Spallation Neutron Source (SNS). The experiment aims to improve the current neutron EDM sensitivity by two orders of magnitude using ultra-cold neutrons produced in superfluid helium-4 and polarized helium-3 as a co-magnetometer. Many feasibility studies have been conducted, including tests of the helium-3 spin precession frequency matching technique. Construction of the new neutron EDM experiment is expected to begin in fiscal year 2010 with the goal of reaching a sensitivity of less than 1×10-28 e-cm.

Visit at CERN

The document provides information for a visit to CERN, the European Organization for Nuclear Research. It begins with an agenda for the visit including a presentation and tour of the experimental areas. It then provides statistics on CERN such as its founding date, member states, staff, and budget. The main goals of CERN are explained as pushing the boundaries of knowledge through high-energy particle collisions to better understand the big bang and develop new technologies. Diagrams show CERN's series of larger and more powerful particle accelerators built over time, culminating in the Large Hadron Collider, a 27km ring that smashes protons together. The document describes the LHC's detectors that observe collision data and CERN's worldwide grid network that

Fundamental Processes in
Organic and Hybrid Solar Cells

Invited talk at the LHP15 / Soltech Meeting at Kloster Banz, Germany
- photogeneration in model system for organic solar cells (pBTTT:PCBM)
- charge carrier recombination in phase separated organic blends by kinetic Monte Carlo simulations
- radiative efficiency and electrooptical reciprocity in organic-inorganic perovskite solar cells
- nongeminate

Calculation of isotopic dipole moments with spectroscopic accuracy

Trabalho apresentado no XVII Symposium on High Resolution Molecular Spectroscopy (HighRus-2012), 2012, Zelenogorsk-Russia. Anals of XVII Symposium on High Resolution Molecular Spectroscopy (HighRus-2012), 2012.

NANO266 - Lecture 13 - Ab initio molecular dyanmics

UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.

optics chapter_07_solution_manual

This document contains problems related to simple harmonic motion, forced vibrations, and the origin of refractive index. Problem 7.1 asks the reader to plot the displacement of a string at various points over time given an equation describing the wave. Problem 7.2 asks the reader to analyze the time variation of displacement in loops of a standing wave given another equation. Problem 7.3 asks the reader to show that a mass dropped in a tunnel through the earth would execute simple harmonic motion and calculate the time period. The remaining problems involve calculating various properties related to simple harmonic motion, polarization, dielectric constants, plasma frequencies, and refractive indices.

CUPC Oct 14, 2015

This document discusses modeling magnetic fields of microtrap arrays for trapping ultracold atoms. It describes how double-loop microtraps can be used to create arrays of traps and transfer atoms between adjacent traps by varying currents. Adding an additional Ioffe coil can generate a trap with a nonzero minimum field to prevent atom loss due to spin flips. The microtraps use much smaller currents than macroscopic traps and allow controlling trap position and depth through bias fields, which could enable applications in precision measurements, quantum information processing, and more.

Gupta Roy MS Thesis Defense

This document summarizes a thesis defense that presented a design for an intrinsic coincident polarimeter using stacked organic photovoltaic (OPV) devices. The polarimeter design leverages the polarization-sensitive properties of OPVs to allow for simultaneous measurement of the Stokes parameters that characterize polarized light. The polarimeter model and calibration procedure were validated experimentally. Results showed the polarimeter could predict the intensity of unknown incident light with 2.2% average error and determine normalized Stokes parameters with 1.2% RMS error. Future work proposed extending the design to include circular polarization detection and modifying the OPV structure.

Two efficient algorithms for drawing accurate and beautiful phonon dispersion

Purpose: easy drawing of accurate and beautiful phonon dispersion in first-principles calculations
See also: Draw phonon dispersion of Si with Quantum Espresso https://gist.github.com/t-nissie/32c10a148a7fc054b836

VPrasad_DAEBRNSHEPDec2014talk

1) The document discusses studies of photon detection efficiency and position resolution of the electromagnetic calorimeter (EMC) at the BESIII experiment using control samples of initial state radiation processes.
2) Datasets of J/psi and psi(3770) decays are used to calibrate the EMC energy and position measurements, which are affected by factors like crystal quality and electronic noise.
3) The photon detection efficiency is found to agree between data and Monte Carlo simulation to within 1%, and the EMC position resolution is improved by applying new correction factors derived from calibration samples.

ppt on the Solar cells understanding semiconductor devices

1. The document provides an overview of semiconductor devices including solar cells, LEDs, transistors, and more through a schedule and explanations of key concepts.
2. The core concepts covered include how solar cells work through photovoltaic absorption, charge carrier generation and transport, and collection.
3. Different types of solar cell materials and designs are examined like silicon, CIGS thin films, and multi-junction cells to understand how their properties influence efficiency.

Semi-empirical Monte Carlo optical-gain modelling of Nuclear Imaging scintill...

The document describes a semi-empirical Monte Carlo model to estimate the optical gain (DOG) of single crystal scintillators excited by gamma rays. The model divides the crystal into layers, uses EGSnrc to simulate gamma ray absorption, and combines this with an analytical model of optical photon propagation between layers. The model is validated against experimental data for LSO:Ce, GSO:Ce and YAP:Ce crystals at 140keV and 364keV. Results show the model can predict DOG values and determine an optimum crystal thickness for different gamma ray energies.

Characterization of Carrier Lifetime

This document provides an overview of carrier lifetime characterization techniques. It discusses that carrier lifetime determines the performance of semiconductor devices and solar cells. It then defines recombination lifetime and generation lifetime. The document proceeds to describe various optical methods to measure carrier lifetime, including photoluminescence, free carrier absorption, photoconductance decay, and their advantages and disadvantages. It provides equations to calculate carrier lifetime from measurements of excess carrier density, conductivity change, and voltage change.

27 Double π0 photoproduction on the neutron at GRAAL - Physics Letters B, Jul...

27 Double π0 photoproduction on the neutron at GRAAL - Physics Letters B, Jul...Cristian Randieri PhD

Double π0 photoproduction on the neutron at GRAAL - Physics Letters B, Elsevier, July 2007, Vol. 651, N. 2-3, pp. 108-113, ISSN: 0370-2693, doi: 10.1016/j.physletb.2007.06.009
di J. Ajaka, Y. Assafiri, O. Bartalini, V. Bellini, S. Bouchigny, M. Castoldi, A. D'Angelo, J. P. Didelez, R. Di Salvo, A. Fantini, L. Fichen, G. Gervino, F. Ghio, B. Girolami, A. Giusa, M. Guidal, E. Hourany, R. Kunne, A. Lapik, P. Levi Sandri, D. Moricciani, A. Mushkarenkov, V. Nedorezov, C. Randieri, N. Rudnev, G. Russo, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge (2007)
Abstract
The photoproduction of double π0 on the neutron is studied in the beam energy range of 0.6 up to 1.5 GeV, using a liquid deuterium target. The cross section and the beam asymmetry are extracted and compared to those previously obtained on a proton target. The theoretical interpretation of these results is given using different models.Loss mechanisms in Polymer-Fullerene Solar Cells

(1) The document discusses loss mechanisms in polymer-fullerene solar cells that limit performance.
(2) With additive, nongeminate recombination occurs via free carrier and trap-assisted recombination. Reconstruction works well.
(3) Without additive, incomplete reconstruction is due to voltage-dependent photogeneration from spatial trapping on fullerene islands.

Phase-field modeling of crystal nucleation II: Comparison with simulations an...

This document summarizes phase-field modeling of crystal nucleation. It discusses:
1) Homogeneous nucleation models using the phase-field method and their comparison to molecular dynamics simulations and experiments for systems like nickel and Lennard-Jones argon.
2) Applications of the phase-field model to heterogeneous systems like ice-water nucleation.
3) The effects of different double-well and interpolation functions on nucleation behavior in phase-field models.

giessen short

Atomic and molecular ion merged-beams experiments provide absolute charge transfer cross section measurements from keV/u to meV/u energies. This allows studying charge transfer processes important for fusion plasmas, astrophysics, and other applications. The technique uses intense ion beams merged with atomic hydrogen beams. Recent work includes measurements of charge transfer from highly charged ions like C6+ and O8+ to gases like hydrogen and krypton, observing x-ray emission. Future work aims to study charge transfer reactions of molecular ions like D2+ and CO+ with hydrogen, comparing results to state-to-state calculations. These experiments provide benchmark data to advance understanding of low-energy ion-atom interactions.

Презентация Microsoft PowerPoint

The mass-energy and angular distributions of fragments produced in the 136Xe+208Pb reaction were measured between 423-617 MeV. Low-energy collisions were found to produce neutron-rich nuclei near N=126, with yields exceeding predictions. Multi-nucleon transfer reactions show promise for synthesizing more neutron-rich superheavy nuclei, though beams heavier than 136Xe are needed. Further studies aim to better understand neutron fluxes in astrophysical r-process nucleosynthesis of transuranic elements.

Measurement-induced long-distance entanglement of superconducting qubits usin...

Measurement-induced long-distance entanglement of superconducting qubits usin...

Iván Brihuega-Probing graphene physics at the atomic scale

Iván Brihuega-Probing graphene physics at the atomic scale

Search for Neutron Electric Dipole Moment

Search for Neutron Electric Dipole Moment

Visit at CERN

Visit at CERN

Fundamental Processes in
Organic and Hybrid Solar Cells

Fundamental Processes in
Organic and Hybrid Solar Cells

Calculation of isotopic dipole moments with spectroscopic accuracy

Calculation of isotopic dipole moments with spectroscopic accuracy

NANO266 - Lecture 13 - Ab initio molecular dyanmics

NANO266 - Lecture 13 - Ab initio molecular dyanmics

optics chapter_07_solution_manual

optics chapter_07_solution_manual

CUPC Oct 14, 2015

CUPC Oct 14, 2015

Gupta Roy MS Thesis Defense

Gupta Roy MS Thesis Defense

Two efficient algorithms for drawing accurate and beautiful phonon dispersion

Two efficient algorithms for drawing accurate and beautiful phonon dispersion

VPrasad_DAEBRNSHEPDec2014talk

VPrasad_DAEBRNSHEPDec2014talk

ppt on the Solar cells understanding semiconductor devices

ppt on the Solar cells understanding semiconductor devices

Semi-empirical Monte Carlo optical-gain modelling of Nuclear Imaging scintill...

Semi-empirical Monte Carlo optical-gain modelling of Nuclear Imaging scintill...

Characterization of Carrier Lifetime

Characterization of Carrier Lifetime

27 Double π0 photoproduction on the neutron at GRAAL - Physics Letters B, Jul...

27 Double π0 photoproduction on the neutron at GRAAL - Physics Letters B, Jul...

Loss mechanisms in Polymer-Fullerene Solar Cells

Loss mechanisms in Polymer-Fullerene Solar Cells

Phase-field modeling of crystal nucleation II: Comparison with simulations an...

Phase-field modeling of crystal nucleation II: Comparison with simulations an...

giessen short

giessen short

Презентация Microsoft PowerPoint

Презентация Microsoft PowerPoint

Novel approaches to optomechanical transduction

Slides for a presentation I gave at the Spring meeting of the German Physical Society in Mainz on March 10, 2017.
In the presentation, I discuss new approaches to frequency conversion of electromagnetic fields using optomechanical interaction. The main figure of merit we are trying to optimize is the transduction bandwidth. I show that the bandwidth can be enhanced by using spatially adiabatic state transfer in an array of conventional optomechanical transducers.

Interference effects in cavity optomechanics with hybridized membranes

1) The document discusses interference effects in cavity optomechanics systems with hybridized membranes. It describes how adding two-level systems or gratings to membranes can lead to Fano resonances in the cavity spectrum.
2) A Fano resonance suppresses Stokes scattering and improves cooling of the membrane. Many physical systems could exhibit these interference effects, including photonic crystal membranes, atom arrays, and excitons in semiconductors.
3) Functionalized membranes have applications in cavity optomechanics and cavity QED such as improved cooling and serving as an end mirror with strong coupling.

Measurement-induced long-distance entanglement with optomechanical transducers

Although superconducting systems provide a promising platform for quantum computing, their networking poses a challenge as they cannot be interfaced to light---the medium used to send quantum signals through channels at room temperature. We show that mechanical oscillators can mediated such coupling and light can be used to measure the joint state of two distant qubits. The measurement provides information on the total spin of the two qubits such that entangled qubit states can be postselected. Entanglement generation is possible without ground-state cooling of the mechanical oscillators for systems with optomechanical cooperativity moderately larger than unity; in addition, our setup tolerates a substantial transmission loss. The approach is scalable to generation of multipartite entanglement and represents a crucial step towards quantum networks with superconducting circuits.

Measurement-induced long-distance entanglement of superconducting qubits usin...Although superconducting systems provide a promising platform for quantum computing, their networking poses a challenge as they cannot be interfaced to light---the medium used to send quantum signals through channels at room temperature. We show that mechanical oscillators can mediated such coupling and light can be used to measure the joint state of two distant qubits. The measurement provides information on the total spin of the two qubits such that entangled qubit states can be postselected. Entanglement generation is possible without ground-state cooling of the mechanical oscillators for systems with optomechanical cooperativity moderately larger than unity; in addition, our setup tolerates a substantial transmission loss. The approach is scalable to generation of multipartite entanglement and represents a crucial step towards quantum networks with superconducting circuits.

Novel approaches to optomechanical transduction

In recent years, mechanical oscillators received attention as a promising tool for frequency conversion between microwaves and light. A general, bi-directional transducer with high efficiency is still far from reach of current technology; finding new strategies for optomechanical transduction allows us to relax the requirements and bring these systems closer to an experimental realization. An interesting example is generation of entanglement between two superconducting qubits using measurement and postselection. Here, the mechanical oscillators interacts directly with the superconducting transmon qubit in such a way that it feels a qubit-state dependent force. This force can then be read out using a cavity field; reading out two such systems sequentially realizes an effective total spin measurement. Starting from a suitable initial state and employing postselection, entanglement can be generated. Another interesting approach is to use an array of optomechanical transducers in which the output fields of one transducer are fed into the input of the next. The periodicity of the array results in a joint dispersion relation for the propagating microwave and optical fields. The resulting structure can be used to control the conversion bandwidth and forward and backward scattering.

Non-linear response of solids: recent results and new developments

This document discusses recent results and new developments in modeling the non-linear response of solids. It begins with an overview of non-linear optics and why it is important for characterizing interfaces and materials excitations. It then describes approaches for calculating non-linear response from first principles, including real-time and frequency domain methods. Specific examples are presented on tuning harmonic generation in lithium niobate alloys and probing dark states with non-linear response.

Localized Characterization of GaAs/AlGaAs Quantum Well Devices

two-dimensional mapping, at pixel resolution, of semiconductor devices in terms of efficiency, electric field distribution, quantum well effects

Wireless Power Transmission for Implantable Medical Devices

Master's thesis presentation at Université Paris-Sud XI.
Author: Quang-Trung Luu
Advisors: Antoine Diet, Yann Le Bihan (Université Paris-Sud, France), and Stavros Koulouridis (University of Patras, Greece)
Research carried out at Laboratoire de Génie Electrique Génie et Electronique de Paris (GeePs) - UMR 8507 CNRS, CentraleSupélec, Université Paris-Sud (Paris XI), Université Pierre et Marie Curie (Paris VI).

24 Polarization observable measurements for γp → K+Λ and γp → K+Σ for energie...

24 Polarization observable measurements for γp → K+Λ and γp → K+Σ for energie...Cristian Randieri PhD

Polarization observable measurements for γp → K+Λ and γp → K+Σ for energies up to 1.5 GeV - The European Physical Journal A, Hadrons and Nuclei, January 2007, Vol. 31, N. 1, pp. 73-93, ISSN: 1434-6001, doi: 10.1140/epja/i2006-10167-8
di A. Lleres, O. Bartalini, V. Bellini, J. P. Bocquet, P. Calvat, M. Capogni, L. Casano, M. Castoldi, A. D'Angelo, J. P. Didelez, R. Di Salvo, A. Fantini, C. Gaulard, G. Gervino, F. Ghio, B. Girolami, A. Giusa, M. Guidal, E. Hourany, V. Kouznetsov, R. Kunne, A. Lapik, P. Levi Sandri, D. Moricciani, A. N. Mushkarenkov, V. Nedorezov, L. Nicoletti, C. Perrin, C. Randieri, D. Rebreyend, F. Renard, N. Rudnev, T. Russew, G. Russo, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge (2007)
Abstract
Beam asymmetries and hyperon recoil polarizations for the reactions γ p → K +Λ and γ p → K +Σ0 have been measured from the threshold production to 1500MeV with the GRAAL facility located at the ESRF in Grenoble. These results complement the database for the beam asymmetry, covering for the first time the production threshold region. Recent theoretical analyses are presented for which the beam asymmetry data bring interesting new information and allow to better determine some resonance parameters. Most importantly, these results strengthen the need of a new D13 state around 1900MeV.Nenopartical optical sensors

This document discusses different types of photonic sensors including surface plasmon resonance sensors, whispering gallery mode sensors, and photonic crystal sensors.
Surface plasmon resonance sensors detect changes at a metal-dielectric interface and are used for ultrasensitive immunoassays. Whispering gallery mode sensors can detect nanoparticles smaller than 100 nm by measuring changes in resonant frequencies as particles deposit inside an optical cavity. Photonic crystal sensors use a photonic band gap to selectively reflect certain wavelengths of light. Changes in materials deposited on the photonic crystal surface cause shifts in the reflected wavelengths that can be measured.

Thesis defense

This document summarizes work towards developing a quantum memory for non-classical light using cold atoms. It discusses generating squeezed vacuum light compatible with an atomic memory using an optical parametric oscillator. The light is characterized and techniques for interfacing it with the memory are explored. This includes creating two atomic ensembles for memory applications and characterizing their properties like storage time and efficiency. The goal is to eventually entangle the two memory ensembles.

Optical interferometery to detect sound waves as an analogue for gravitationa...

This document describes an experiment using a Michelson interferometer to detect sound waves as an analogue for gravitational waves. A tuning fork resonating at 440Hz and a piezoelectric crystal were used to generate sound waves near one arm of the interferometer. An Arduino and oscilloscope measured the resulting interference patterns. The Arduino detected the tuning fork frequency accurately but the oscilloscope only detected around half the frequency due to its limited sampling. Multiple constituent frequencies were detected from hand claps, mimicking bursts from supernovae. While the setup could detect these 'fake' gravitational waves, its low sampling rate limited the detectable frequency window.

Noise Resilience of Variational Quantum Compiling

APS March meeting 2020
Variational hybrid quantum-classical algorithms (VHQCAs) are near-term algorithms that leverage classical optimization to minimize a cost function, which is efficiently evaluated on a quantum computer. Recently VHQCAs have been proposed for quantum compiling, where a target unitary U is compiled into a short-depth gate sequence V. In this work, we report on a surprising form of noise resilience for these algorithms. Namely, we find one often learns the correct gate sequence V (i.e., the correct variational parameters) despite various sources of incoherent noise acting during the cost-evaluation circuit. Our main results are rigorous theorems stating that the optimal variational parameters are unaffected by a broad class of noise models, such as measurement noise, gate noise, and Pauli channel noise. Furthermore, our numerical implementations on IBM's noisy simulator demonstrate resilience when compiling the quantum Fourier transform, Toffoli gate, and W-state preparation. Hence, variational quantum compiling, due to its robustness, could be practically useful for noisy intermediate-scale quantum devices. Finally, we speculate that this noise resilience may be a general phenomenon that applies to other VHQCAs such as the variational quantum eigensolver.

Uv Vis Calculated Of Mv2+ And Mv+

This document discusses simulating UV-vis spectra of methyl viologen and its radical cation using time-dependent density functional theory (TD-DFT). It optimizes the geometries of methyl viologen and its radical cation using DFT and discusses using TD-DFT with a 6-311G** basis set to simulate the UV-vis spectra. It also plans to simulate the UV-vis spectra using a multi-reference method called CASPT2.

Generation and application of attosecond laser pulse

Attosecond pulses produced by using HHG in gases, it is possible to make a few simple statements: attosecond pulses are unique tools for the investigation of ultrafast electronic processes in atoms, molecules, nano structures and solids. Impressive progress has been demonstrated from the technological point of view, with the possibility to routinely generate attosecond pulses in perfectly reproducible ways.

Gaussian control and readout of levitated nanoparticles via coherent scattering

Optically levitated nanoparticles present an attractive optomechanical platform owing to their lack of clamping losses. The most promising approach to control the state of nanoparticle motion is coherent scattering of tweezer photons into a cavity mode. Originally proposed as a technique for cooling the motion of atoms and ions, this mechanism has recently been used to cool the motion of a nanoparticle to its quantum ground state for the first time. In my presentation, I will discuss how coherent scattering can be used to create and measure complex motional states of levitated nanoparticles. Coherent scattering gives us access to the same basic types of interaction as the more usual radiation-pressure interaction (of the beam-splitter and two-mode-squeezing type) allowing the same protocols to be realized. An important distinction—relevant particularly for quantum nondemolition readout of nanoparticle motion—is that coherent scattering can be accompanied by additional effects modifying the free nanoparticle evolution. I will discuss these differences and address the consequences they have for controlling and measuring nanoparticle motion in the quantum regime.

nothing

This document contains physics examination papers from 2008-2012 administered by the Central Board of Secondary Education (CBSE) in Delhi, India. It lists the contents which include CBSE examination papers from Delhi and All India in those years, as well as foreign papers. A sample paper from the 2008 Delhi exam is then provided, consisting of 30 multiple choice questions testing concepts in physics.

Ldb Convergenze Parallele_sorba_01

This document provides an overview of the Institute of Nanoscience and its research activities related to semiconductor nanostructures and their applications. The institute has over 250 researchers studying the fundamental properties and manipulation of nanoscale systems through synthesis, fabrication, experimental and theoretical studies of nanostructures and devices. Key areas of research include semiconductor nanowires for applications in electronics, optoelectronics and spintronics. Heterostructured nanowires of InAs, InSb and InP are investigated for high mobility transistors and terahertz detectors. Strain-driven self-assembly is used to create 3D nanostructures for applications in sensing, energy harvesting and photonics.

Ldb Convergenze Parallele_11

1. Ion traps use oscillating electric fields to confine charged particles like ions in three dimensions. Paul traps are a common type of ion trap that use radio frequency (RF) and DC electric fields to dynamically trap ions.
2. Trapped ions can be laser cooled and manipulated with laser beams, allowing experiments in quantum optics and quantum information processing. Multiple ions can be trapped together and their vibrational modes and interactions studied.
3. By coupling trapped ion internal states like atomic energy levels to motional modes using laser beams, quantum gates can be implemented to process quantum information with ions. This enables building basic elements of a trapped ion quantum computer.

2016.06.21 lasuam NanoFrontMag

1) Graphene has potential for spintronics applications due to its long spin diffusion length and ability to manipulate spin. Intercalating graphene with Pb on an Ir substrate induces a giant spin-orbit coupling that splits graphene's bands.
2) Depositing molecules like TCNQ on graphene can induce a Kondo effect and long-range magnetic order. TCNQ forms nearly flat, half-filled bands predicted to have a ferromagnetic ground state.
3) Pb intercalated graphene on Ir has properties resembling Landau levels without a magnetic field, with quantized resistance and possible applications in topological insulators.

Novel approaches to optomechanical transduction

Novel approaches to optomechanical transduction

Interference effects in cavity optomechanics with hybridized membranes

Interference effects in cavity optomechanics with hybridized membranes

Measurement-induced long-distance entanglement with optomechanical transducers

Measurement-induced long-distance entanglement with optomechanical transducers

Measurement-induced long-distance entanglement of superconducting qubits usin...

Measurement-induced long-distance entanglement of superconducting qubits usin...

Novel approaches to optomechanical transduction

Novel approaches to optomechanical transduction

Non-linear response of solids: recent results and new developments

Non-linear response of solids: recent results and new developments

Localized Characterization of GaAs/AlGaAs Quantum Well Devices

Localized Characterization of GaAs/AlGaAs Quantum Well Devices

Wireless Power Transmission for Implantable Medical Devices

Wireless Power Transmission for Implantable Medical Devices

24 Polarization observable measurements for γp → K+Λ and γp → K+Σ for energie...

24 Polarization observable measurements for γp → K+Λ and γp → K+Σ for energie...

Nenopartical optical sensors

Nenopartical optical sensors

Thesis defense

Thesis defense

Optical interferometery to detect sound waves as an analogue for gravitationa...

Optical interferometery to detect sound waves as an analogue for gravitationa...

Noise Resilience of Variational Quantum Compiling

Noise Resilience of Variational Quantum Compiling

Uv Vis Calculated Of Mv2+ And Mv+

Uv Vis Calculated Of Mv2+ And Mv+

Generation and application of attosecond laser pulse

Generation and application of attosecond laser pulse

Gaussian control and readout of levitated nanoparticles via coherent scattering

Gaussian control and readout of levitated nanoparticles via coherent scattering

nothing

nothing

Ldb Convergenze Parallele_sorba_01

Ldb Convergenze Parallele_sorba_01

Ldb Convergenze Parallele_11

Ldb Convergenze Parallele_11

2016.06.21 lasuam NanoFrontMag

2016.06.21 lasuam NanoFrontMag

Transformations of continuous-variable entangled states of light

Gaussian states and Gaussian transformations represent an interesting counterpart to two-level photonic systems in the field of quantum information processing. On the theoretical side, Gaussian states are easily described using first and second moments of the quadrature operators; from the experimental point of view, Gaussian operations can be implemented using linear optics and optical parametric amplifiers. The biggest advantage compared to two-level photonic systems, is deterministic generation of entangled states in parametric amplifiers and highly efficient homodyne detection. In this presentation, we propose new protocols for manipulation of entanglement of Gaussian states.
Firstly, we study entanglement concentration of split single-mode squeezed vacuum states by photon subtraction enhanced by local coherent displacements. These states can be obtained by mixing a single-mode squeezed vacuum state with vacuum on a beam splitter and are, therefore, generated more easily than two-mode squeezed vacuum states. We show that performing local coherent displacements prior to photon subtraction can lead to an enhancement of the output entanglement. This is seen in weak-squeezing approximation where destructive quantum interference of dominant Fock states occurs, while for arbitrarily squeezed input states, we analyze a realistic scenario, including limited transmittance of tap-off beam splitters and limited efficiency of heralding detectors.
Next, motivated by results obtained for bipartite Gaussian states, we study symmetrization of multipartite Gaussian states by local Gaussian operations. Namely, we analyze strategies based on addition of correlated noise and on quantum non-demolition interaction. We use fidelity of assisted quantum teleportation as a figure of merit to characterize entanglement of the state before and after the symmetrization procedure. Analyzing the teleportation protocol and considering more general transformations of multipartite Gaussian states, we show that the fidelity can be improved significantly.

Improved optomechanical interactions for quantum technologies

Cavity optomechanics reached remarkable success in coupling optical and mechanical degrees of freedom. The standard mechanism relies on dispersive interaction wherein a cavity mode acquires a frequency shift proportional to the mechanical displacement. Efficient coupling is, however, often impeded by large cavity decay rates or strong heating of the mechanical element by optical absorption. In this talk, I will present two strategies to circumvent this problem. In the first one, a membrane doped with an ensemble of two-level emitters or patterned with a photonic-crystal structure is used as a mechanical element. The hybridization of the cavity mode with the membrane’s internal resonance leads to a modified response, resulting in an effective narrow cavity linewidth. I will show how such systems can be described quantum mechanically and discuss how optomechanical sideband cooling can be improved by the presence of the internal resonance. Second, I will discuss optomechanics with levitated particles and show how coherent scattering can be used to generate strong mechanical squeezing. In this system, the standard dispersive interaction is replaced by scattering of the trapping beam into an empty cavity mode. This process can result in strong, controllable coupling between the cavity mode and the motion of the particle with minimal absorption heating. I will also briefly outline how this type of interaction can be used to engineer coupling between different center-of-mass modes of the particle allowing, in principle, full optomechanical control of the particle motion.

Entangling distant superconducting qubits using nanomechanical transducers

Optical fields are ideal for transmission of quantum information due to low losses and high repetition rates. Microwave fields, on the other hand, can be used to manipulate superconducting systems that belong among the most promising candidates for quantum computing architecture. A device enabling conversion between electromagnetic fields of such distinct frequencies would thus represent a basic building block of future quantum computer networks. Nanomechanical oscillators represent an extremely suitable platform for this task as they can couple to both optical and microwave fields. The electromechanical interaction is achieved through capacitance of an LC circuit, where the change of voltage couples to the position of a mechanical membrane forming one plate of the capacitor, while coupling to the visible light is due to radiation pressure from light reflected off the membrane.
Here we study how such nanomechanical transducers can be employed to generate entanglement between two superconducting qubits placed on two separate chips. Our protocol is based on continuous Bell measurement of the outgoing light fields and applying feedback on the qubits. With such a setup, it is, in principle, possible to generate entanglement between qubits deterministically in the steady state.

Displacement-enhanced continuous-variable entanglement concentration

We study entanglement concentration of continuous variable Gaussian states by local photon subtractions enhanced by coherent displacements. Instead of the previously considered symmetric two-mode squeezed vacuum states, we investigate the protocol for input states in the form of split single-mode squeezed vacuum, i.e., states obtained by mixing a single-mode squeezed vacuum with a vacuum state on a beam splitter, which is an experimentally highly relevant configuration. We analyze two scenarios in which the displacement-enhanced photon subtraction is performed either only on one, or on both of the modes and show that local displacements can lead to improved performance of the concentration protocol.

Spatially adiabatic frequency conversion in opto-electro-mechanical arrays

Optoelectromechanical systems offer a promising route towards frequency conversion between microwaves and light and towards building quantum networks of superconducting circuits. Current theoretical and experimental efforts focus on approaches based on either optomechanically induced transparency or adiabatic passage. The former has the advantage of working with time-independent control but only in a limited bandwidth (typically much smaller than the cavity linewidth); the latter can, in principle, be used to increase the bandwidth but at the expense of working with time-dependent control fields and with strong optomechanical coupling. In my presentation, I will show that an array of optoelectromechanical transducers can overcome this limitation and reach a bandwidth that is larger than the cavity linewidth. The coupling rates are varied in space throughout the array so that a mechanically dark mode of the propagating fields adiabatically changes from microwave to optical or vice versa. This strategy also leads to significantly reduced thermal noise with the collective optomechanical cooperativity being the relevant figure of merit. I will also demonstrate that, remarkably, the bandwidth enhancement per transducer element is largest for small arrays. With these features the scheme is particularly relevant for improving the conversion bandwidth in state-of-the-art experimental setups.

Cavity optomechanics with variable polarizability mirrors

Cavity optomechanics with frequency-independent high-reflectivity mirrors shows different operation regimes distinguished by the ratio of the mechanical frequency and the photon loss rate. Working in the resolved-sideband regime thus enables cooling or amplification of the mechanical motion while optomechanical systems in the bad-cavity limit can be used to efficiently measure the mechanical motion. The use of mirrors with frequency-dependent reflectivity can bring new, interesting effects, such as Doppler cooling of the mechanical motion or modification of the sideband ratio. Here, we develop a full quantum theory of cavity optomechanics where the mechanically compliant mirror has reflectivity that strongly depends on the frequency of the incident light and identify regimes where these new optomechanical effects can be observed. These results are relevant for mirrors formed by self-assembled two-dimensional atomic layers, where the reflectivity is sharply peaked around the internal resonance of the atoms, or for structured membranes with engineered spatial defects.

Interference effects in doped cavity optomechanics

Radiation pressure forces in cavity optomechanics allow for efficient cooling of vibrational modes of macroscopic mechanical resonators, the manipulation of their quantum states, as well as generation of optomechanical entanglement. The standard mechanism relies on the cavity photons directly modifying the state of the mechanical resonator. Hybrid cavity optomechanics provides an alternative approach by coupling mechanical objects to quantum emitters, either directly or indirectly via the common interaction with a cavity field mode. While many approaches exist, they typically share a simple effective description in terms of a single force acting on the mechanical resonator. More generally, one can study the interplay between various forces acting on the mechanical resonator in such hybrid mechanical devices. This interplay can lead to interference effects that may, for instance, improve cooling of the mechanical motion or lead to generation of entanglement between various parts of the hybrid device. Here, we provide such an example of a hybrid optomechanical system where an ensemble of quantum emitters is embedded into the mechanical resonator formed by a vibrating membrane. The interference between the radiation pressure force and the mechanically modulated Tavis--Cummings interaction leads to enhanced cooling dynamics in regimes in which neither force is efficient by itself. Our results pave the way towards engineering novel optomechanical interactions in hybrid optomechanical systems.

Motional Gaussian states and gates for a levitating particle

Coherent scattering has recently attracted attention as a means of controlling the motion of levitated particles in three dimensions using a single optical cavity. In these systems, scattering of photons from the trapping field to a cavity mode has been used to cool all three modes of the centre-of-mass motion of levitated particles. The possibility of employing coherent scattering for more general quantum control has, however, not yet been discussed in the literature. Here, we present strategies for generating nonclassical correlations and for engineering interactions between motional modes of levitated particles using coherent scattering. We expand the theory developed by Gonzalez-Ballestero et al. to realize more general bilinear interactions in levitated optomechanics with coherent scattering. Going beyond the simple stationary picture, we introduce amplitude modulation as an important tool to modify the optomechanical interaction and discuss how it can be used to resonantly enhanced certain parts of the interaction, allowing, for example, strong one- and two-mode squeezing of motion. Our results thus show the potential of using coherent scattering for full quantum control of the motion of levitated particles.

Transformations of continuous-variable entangled states of light

Transformations of continuous-variable entangled states of light

Improved optomechanical interactions for quantum technologies

Improved optomechanical interactions for quantum technologies

Entangling distant superconducting qubits using nanomechanical transducers

Entangling distant superconducting qubits using nanomechanical transducers

Measurement-induced long-distance entanglement of superconducting qubits usin...

Measurement-induced long-distance entanglement of superconducting qubits usin...

Displacement-enhanced continuous-variable entanglement concentration

Displacement-enhanced continuous-variable entanglement concentration

Spatially adiabatic frequency conversion in opto-electro-mechanical arrays

Spatially adiabatic frequency conversion in opto-electro-mechanical arrays

Cavity optomechanics with variable polarizability mirrors

Cavity optomechanics with variable polarizability mirrors

Interference effects in doped cavity optomechanics

Interference effects in doped cavity optomechanics

Motional Gaussian states and gates for a levitating particle

Motional Gaussian states and gates for a levitating particle

BÀI TẬP DẠY THÊM TIẾNG ANH LỚP 7 CẢ NĂM FRIENDS PLUS SÁCH CHÂN TRỜI SÁNG TẠO ...

BÀI TẬP DẠY THÊM TIẾNG ANH LỚP 7 CẢ NĂM FRIENDS PLUS SÁCH CHÂN TRỜI SÁNG TẠO ...Nguyen Thanh Tu Collection

https://app.box.com/s/qhtvq32h4ybf9t49ku85x0n3xl4jhr15C1 Rubenstein AP HuG xxxxxxxxxxxxxx.pptx

C1 Rubenstein

What is Digital Literacy? A guest blog from Andy McLaughlin, University of Ab...

What is Digital Literacy? A guest blog from Andy McLaughlin, University of Aberdeen

Pollock and Snow "DEIA in the Scholarly Landscape, Session One: Setting Expec...

Pollock and Snow "DEIA in the Scholarly Landscape, Session One: Setting Expec...National Information Standards Organization (NISO)

This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.How to Manage Your Lost Opportunities in Odoo 17 CRM

Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM

Main Java[All of the Base Concepts}.docx

This is part 1 of my Java Learning Journey. This Contains Custom methods, classes, constructors, packages, multithreading , try- catch block, finally block and more.

Leveraging Generative AI to Drive Nonprofit Innovation

In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)

How to Fix the Import Error in the Odoo 17

An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.

คำศัพท์ คำพื้นฐานการอ่าน ภาษาอังกฤษ ระดับชั้น ม.1

คำศัพท์เบื้องต้นสำหรับอ่าน ของนักเรียนชั้น ม.1

writing about opinions about Australia the movie

writing about opinions about Australia the movie

How to Create a More Engaging and Human Online Learning Experience

How to Create a More Engaging and Human Online Learning Experience Wahiba Chair Training & Consulting

Wahiba Chair's Talk at the 2024 Learning Ideas Conference. How to Make a Field Mandatory in Odoo 17

In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.

PCOS corelations and management through Ayurveda.

This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.

The History of Stoke Newington Street Names

Presented at the Stoke Newington Literary Festival on 9th June 2024
www.StokeNewingtonHistory.com

Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptx

Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024

Wound healing PPT

This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
Healing is the body’s response to injury in an attempt to restore normal structure and functions.
Healing can occur in two ways: Regeneration and Repair
There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
Complications of wound healing like infection, hyperpigmentation of scar, contractures, and keloid formation.

BÀI TẬP BỔ TRỢ TIẾNG ANH LỚP 9 CẢ NĂM - GLOBAL SUCCESS - NĂM HỌC 2024-2025 - ...

BÀI TẬP BỔ TRỢ TIẾNG ANH LỚP 9 CẢ NĂM - GLOBAL SUCCESS - NĂM HỌC 2024-2025 - ...Nguyen Thanh Tu Collection

https://app.box.com/s/tacvl9ekroe9hqupdnjruiypvm9rdanespot a liar (Haiqa 146).pptx Technical writhing and presentation skills

sample presentation

Traditional Musical Instruments of Arunachal Pradesh and Uttar Pradesh - RAYH...

Traditional Musical Instruments of Arunachal Pradesh and Uttar Pradesh

BÀI TẬP DẠY THÊM TIẾNG ANH LỚP 7 CẢ NĂM FRIENDS PLUS SÁCH CHÂN TRỜI SÁNG TẠO ...

BÀI TẬP DẠY THÊM TIẾNG ANH LỚP 7 CẢ NĂM FRIENDS PLUS SÁCH CHÂN TRỜI SÁNG TẠO ...

C1 Rubenstein AP HuG xxxxxxxxxxxxxx.pptx

C1 Rubenstein AP HuG xxxxxxxxxxxxxx.pptx

What is Digital Literacy? A guest blog from Andy McLaughlin, University of Ab...

What is Digital Literacy? A guest blog from Andy McLaughlin, University of Ab...

Pollock and Snow "DEIA in the Scholarly Landscape, Session One: Setting Expec...

Pollock and Snow "DEIA in the Scholarly Landscape, Session One: Setting Expec...

How to Manage Your Lost Opportunities in Odoo 17 CRM

How to Manage Your Lost Opportunities in Odoo 17 CRM

Main Java[All of the Base Concepts}.docx

Main Java[All of the Base Concepts}.docx

Leveraging Generative AI to Drive Nonprofit Innovation

Leveraging Generative AI to Drive Nonprofit Innovation

How to Fix the Import Error in the Odoo 17

How to Fix the Import Error in the Odoo 17

MARY JANE WILSON, A “BOA MÃE” .

MARY JANE WILSON, A “BOA MÃE” .

คำศัพท์ คำพื้นฐานการอ่าน ภาษาอังกฤษ ระดับชั้น ม.1

คำศัพท์ คำพื้นฐานการอ่าน ภาษาอังกฤษ ระดับชั้น ม.1

writing about opinions about Australia the movie

writing about opinions about Australia the movie

How to Create a More Engaging and Human Online Learning Experience

How to Create a More Engaging and Human Online Learning Experience

How to Make a Field Mandatory in Odoo 17

How to Make a Field Mandatory in Odoo 17

PCOS corelations and management through Ayurveda.

PCOS corelations and management through Ayurveda.

The History of Stoke Newington Street Names

The History of Stoke Newington Street Names

Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptx

Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptx

Wound healing PPT

Wound healing PPT

BÀI TẬP BỔ TRỢ TIẾNG ANH LỚP 9 CẢ NĂM - GLOBAL SUCCESS - NĂM HỌC 2024-2025 - ...

BÀI TẬP BỔ TRỢ TIẾNG ANH LỚP 9 CẢ NĂM - GLOBAL SUCCESS - NĂM HỌC 2024-2025 - ...

spot a liar (Haiqa 146).pptx Technical writhing and presentation skills

spot a liar (Haiqa 146).pptx Technical writhing and presentation skills

Traditional Musical Instruments of Arunachal Pradesh and Uttar Pradesh - RAYH...

Traditional Musical Instruments of Arunachal Pradesh and Uttar Pradesh - RAYH...

- 1. Quantum networks with superconducting circuits and optomechanical transducers Ondřej Černotík Leibniz Universität Hannover IST Austria, 10 November 2016 -
- 2. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Superconducting systems are among the best candidates for quantum computers. 2 • Quantum gates and processors L. DiCarlo et al., Nature 460, 240 (2009); ibid. 467, 574 (2010); A. Fedorov et al., Nature 481, 170 (2011) • Quantum teleportation L. Steffen et al., Nature 500, 319 (2013) • Quantum simulations A. Houck et al., Nature Physics 8, 292 (2012) • Quantum error correction A. Córcoles et al., Nature Commun. 6, 6979 (2015); J. Kelly et al., Nature 519, 66 (2015); D. Ristè et al., Nature Commun. 6, 6983 (2015) R. Schoelkopf, Yale
- 3. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Light is ideal for quantum communication due to low losses and noise. 3 • Quantum key distribution F. Grosshans et al., Nature 421, 238 (2003); T. Schmitt-Manderbach et al., PRL 98, 010504 (2007); H. Yin et al., PRL 117, 190501 (2016) • Quantum teleportation D. Bouwmeester et al., Nature 390, 575 (1997); A. Furusawa et al., Science 282, 706 (1998); H. Yonezawa et al., Nature 431, 430 (2004); T. Herbst et al., PNAS 112, 14202 (2015) • Loophole-free Bell test B. Hensen et al., Nature 526, 682 (2015); M. Giustina et al., PRL 115, 250401 (2015); L. Shalm et al., ibid., 250402 (2015) A. Zeilinger
- 4. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ There is a large gap between superconducting and optical systems. 4 Superconducting circuits Optical communication 10 GHz 200 THzfrequency 625 0.03thermal occupation (300 K) 0.5 K 10,000 K ground state temperature
- 5. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Mechanical oscillators can mediate coupling between microwaves and light. 5 R. Andrews et al., Nature Phys. 10, 321 (2014) K. Stannigel et al., PRL 105, 220501 (2010)
- 6. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ 6 Parity measurements in circuit QED Optomechanical force sensing Long-distance entanglement of superconducting qubits Fext
- 7. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Full control of a qubit is possible using an electromagnetic ﬁeld. 7 Hint = g(a + + a† ) A. Blais et al., PRA 69, 062920 (2004) Jaynes–Cummings interaction
- 8. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Full control of a qubit is possible using an electromagnetic ﬁeld. 8 Hint = g2 a† a z A. Blais et al., PRA 69, 062920 (2004) dispersive interaction
- 9. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Dispersive coupling can be used to read out the qubit state. 9 |0i |1i R. Vijay et al., PRL 106, 110502 (2011) K. Murch et al., Nature 502, 211 (2013) Hint = g2 a† a z
- 10. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Spin measurement can be used to generate entanglement of two qubits. 10 C. Hutchison et al., Canadian J. Phys. 87, 225 (2009) N. Roch et al., PRL 112, 170501 (2014) |11i |00i |01i + |10i | 0i = (|0i + |1i)(|0i + |1i)
- 11. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Optomechanical interaction arises due to radiation pressure. 11 a x !, ⌦, ¯n !(x) ⇡ !(0) + d! dx x Cavity frequency: g0 = d! dx xzpf = ! L xzpfCoupling strength: xzpf = r ~ 2m⌦ x = xzpf (b + b† ), Hamiltonian: H = ~!(x)a† a + ~⌦b† b H = ~!a† a + ~⌦b† b + ~g0a† a(b + b† ) M. Aspelmeyer, et al., RMP 86, 1391 (2014)
- 12. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ ⌦ Strong coupling can be achieved using laser driving. 12 Optomechanical coupling is weak g0 = ! xzpf L ⇡ 25 Hz Solution: strong optical drive a ! ↵ + a Interaction Hamiltonian Hint = ~g0↵(a + a† )(b + b† ) M. Aspelmeyer, et al., RMP 86, 1391 (2014) Red-detuned drive: Hint ⇡ ~g(a† b + b† a) Optomechanical cooling !L = ! ⌦
- 13. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ ⌦ Strong coupling can be achieved using laser driving. 13 Optomechanical coupling is weak g0 = ! xzpf L ⇡ 25 Hz Solution: strong optical drive a ! ↵ + a ⌦ Interaction Hamiltonian Hint = ~g0↵(a + a† )(b + b† ) M. Aspelmeyer, et al., RMP 86, 1391 (2014) Blue-detuned drive: Hint ⇡ ~g(ab + a† b† ) Two-mode squeezing !L = ! + ⌦
- 14. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ ⌦ Strong coupling can be achieved using laser driving. 14 Optomechanical coupling is weak g0 = ! xzpf L ⇡ 25 Hz Solution: strong optical drive a ! ↵ + a Interaction Hamiltonian Hint = ~g0↵(a + a† )(b + b† ) M. Aspelmeyer, et al., RMP 86, 1391 (2014) Resonant drive: Hint ⇡ ~g(a + a† )(b + b† ) Position readout ! = !L
- 15. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Standard quantum limit bounds the sensitivity of displacement measurements. 15 A. Clerk et al., RMP 82, 1155 (2010) M. Aspelmeyer et al., RMP 86, 1391 (2014) ˙x = !mp ˙p = !mx p g(a + a† ) + ⇠ + Fext ˙a = 2 a igx + p ain Fext
- 16. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Standard quantum limit bounds the sensitivity of displacement measurements. 16 A. Clerk et al., RMP 82, 1155 (2010) M. Aspelmeyer et al., RMP 86, 1391 (2014) Fext pout = i(aout a† out) = 4g!m p (!2 m !2 + i !)( + 2i!) ✓ Fext + ⇠ 2g p + 2i! xin ◆ + 2i! + 2i! pin
- 17. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Optomechanical transducer acts as a force sensor. 17 F = ~ /( p 2xzpf ) S2 F (!) = x2 zpf /[8g2 2 m(!)]Sensitivity: ⌧meas = S2 F (!) F2 = !2 m 16 2g2 ⌧ T1,2Measurement time: H = z(b + b† ) + !mb† b + g(a + a† )(b + b† )
- 18. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ The thermal mechanical bath affects the qubit. 18 mech = S2 f (!) = 2 2 !2 m ¯nDephasing rate: ⌧meas < 1 mech ! C = 4g2 ¯n > 1 2
- 19. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ The system can be modelled using a conditional master equation. 19 D[O]⇢ = O⇢O† 1 2 (O† O⇢ + ⇢O† O) H[O]⇢ = (O hOi)⇢ + ⇢(O† hO† i) H. Wiseman & G. Milburn, Quantum measurement and control (Cambridge) d⇢ = i[H, ⇢]dt + Lq⇢dt + 2X j=1 {(¯n + 1)D[bj] + ¯nD[b† j]}⇢dt + D[a1 a2]⇢dt + p H[i(a1 a2)]⇢dW H = 2X j=1 j z(bj + b† j) + !mb† jbj + g(aj + a† j)(bj + b† j) + i 2 (a1a† 2 a2a† 1)
- 20. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ The transducer is Gaussian and can be adiabatically eliminated. 20 OC et al., PRA 92, 012124 (2015)ˇ 2 qubits Mechanics, light
- 21. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ We obtain an effective equation for the qubits. 21 d⇢q = 2X j=1 1 T1 D[ j ] + ✓ 1 T2 + mech ◆ D[ j z] ⇢qdt + measD[ 1 z + 2 z]⇢qdt + p measH[ 1 z + 2 z]⇢qdW meas = 16 2 g2 !2 m , mech = 2 !2 m (2¯n + 1)
- 22. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Optical losses introduce additional dephasing. 22 p ⌘ measH[ 1 z + 2 z]⇢q (1 ⌧) measD[ 1 z]⇢q
- 23. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ A transmon qubit can capacitively couple to a nanobeam oscillator. 23 G. Anetsberger et al., Nature Phys. 5, 909 (2009) J. Pirkkalainen et al., Nat. Commun. 6, 6981 (2015) = 2⇡ ⇥ 5.8 MHz g = 2⇡ ⇥ 900 kHz = 2⇡ ⇥ 39MHz !m = 2⇡ ⇥ 8.7 MHz Qm = 5 ⇥ 104 T = 20 mK ¯n = 48 T1,2 = 20 µs C = 10
- 24. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ A transmon qubit can capacitively couple to a nanobeam oscillator. 24 = 2⇡ ⇥ 5.8 MHz g = 2⇡ ⇥ 900 kHz = 2⇡ ⇥ 39MHz !m = 2⇡ ⇥ 8.7 MHz Qm = 5 ⇥ 104 T = 20 mK ¯n = 48 T1,2 = 20 µs C = 10 ⌘ Psucc Psucc OC and K. Hammerer, PRA 94, 012340 (2016)ˇ
- 25. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ With high-frequency mechanical oscillators, modulated interaction can be used. 25 H = z(b + b† ) ig(a + a† )(b b† ) meas = 16 2 g2 2 , mech = 2 (2¯n + 1)
- 26. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Microwave cavity can improve the lifetime of the qubit. 26 meas = 256 2 g2 ag2 c 2 a!2 mc , deph = 4 2 a + 256 2 g4 a 3 a!2 m + 16 2 g2 a 2 a!2 m (2¯n + 1) H = z(a + a† ) iga(a a† )(b + b† ) + !mb† b + gc(c + c† )(b + b† ) a b c
- 27. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Both techniques can also be combined in one system. 27 a b c H = z(a + a† ) iga(a a† )(b + b† ) igc(c + c† )(b b† ) meas = 1024 2 g2 ag2 c 2 a 2c , deph = 4 2 a + 64 2 g2 a 2 a (2¯n + 1)
- 28. Ondrej Cernotík (Hannover): Quantum networks with SC qubits and OM transducersˇˇ Mechanical oscillators can mediate interaction between light and SC qubits. 28 OC and K. Hammerer, PRA 94, 012340 (2016)ˇ - C = 4g2 ¯n > 1 2 • Strong optomechanical cooperativity, • Sufﬁcient qubit lifetime