The document summarizes research on using proximity-induced superconducting correlations in mesoscopic conductors to implement quantum detectors. It describes how superconductivity can modify the density of states in normal metals through the proximity effect. It then introduces the Superconducting QUantum Interference Proximity Transistor (SQUIPT), a novel quantum interferometer that uses this effect for high-sensitivity magnetic flux detection, and presents theoretical predictions and experimental results demonstrating its behavior and advantages over DC SQUIDs.
Anisotropic Kondo effect
Wael Chibani (email: chibani@fhi-berlin.mpg.de)
Using the numerical renormalization group (NRG), we study the STM tunneling current through a Co atom embedded on an anisotropic lattice and experiencing a magnetic field in both directions, parallel and perpendicular to the anisotropy, as was measured by Otte et al. [1]. We introduce the Kondo-Anderson hybrid model (KAHM) Hamiltonian, by which we describe the system, where we take the spin of the Co atom as being S=3/2, and present the mapping of the self energy representation [2] onto our model. After discussing the easy-axis and easy-plan anisotropy, we demonstrate, that our problem is best described by an easy-axis anisotropy. Moreover, the experimental spectra show a dependence of the splitting of the Kondo resonance at finite magnetic fields on the direction of the magnetic field with respect to the anisotropy, which we will also discuss.
Finally, when comparing our NRG calculated current with the experimentally measured one, we found, that, the Kondo temperature as given in the experiment is too small and thus, we choose an effective temperature to describe the system.
[1] Otte A. F., Ternes. M., von Bergmann K., Loth S., Brune H. Lutz C. P., Hirjibehedin C. F. and Heinrich A. J., Nature Physics, Vol 4, November 2008.
[2] Bulla R., Hewson A. C. and Pruschke T., J.Phys. : Condens. Matter 10, 8365- 8380 (1998).
Magnetic Gold; Structure Dependent Ferromagnetism in Au4VDamon Jackson
A description of the ferromagnetic interactions found in crystallographic Au4V is investigated through high pressure (P<35 GPa) electrical resistivity measurements. The results suggest an intimate connection between crystallographic structure and ferromagnetism for this material.
Anisotropic Kondo effect
Wael Chibani (email: chibani@fhi-berlin.mpg.de)
Using the numerical renormalization group (NRG), we study the STM tunneling current through a Co atom embedded on an anisotropic lattice and experiencing a magnetic field in both directions, parallel and perpendicular to the anisotropy, as was measured by Otte et al. [1]. We introduce the Kondo-Anderson hybrid model (KAHM) Hamiltonian, by which we describe the system, where we take the spin of the Co atom as being S=3/2, and present the mapping of the self energy representation [2] onto our model. After discussing the easy-axis and easy-plan anisotropy, we demonstrate, that our problem is best described by an easy-axis anisotropy. Moreover, the experimental spectra show a dependence of the splitting of the Kondo resonance at finite magnetic fields on the direction of the magnetic field with respect to the anisotropy, which we will also discuss.
Finally, when comparing our NRG calculated current with the experimentally measured one, we found, that, the Kondo temperature as given in the experiment is too small and thus, we choose an effective temperature to describe the system.
[1] Otte A. F., Ternes. M., von Bergmann K., Loth S., Brune H. Lutz C. P., Hirjibehedin C. F. and Heinrich A. J., Nature Physics, Vol 4, November 2008.
[2] Bulla R., Hewson A. C. and Pruschke T., J.Phys. : Condens. Matter 10, 8365- 8380 (1998).
Magnetic Gold; Structure Dependent Ferromagnetism in Au4VDamon Jackson
A description of the ferromagnetic interactions found in crystallographic Au4V is investigated through high pressure (P<35 GPa) electrical resistivity measurements. The results suggest an intimate connection between crystallographic structure and ferromagnetism for this material.
Enzo palmieri the problem of heat transfer at liquid helium temperatures 1st...thinfilmsworkshop
For decades the attention of Scientists working on the performance improvement of superconducting cavities has been focused onto the study of the cavity interior and more precisely to the optimization of the first hundreds nanolayers of the Niobium surface exposed to the electromagnetic fields. In the meantime, little attention has been played to the status of the external surface in contact with liquid Helium. In our analysis we will see that both from the literature analysis and from the experimental results, the status of the cavity external surface has a non-negligible importance.
I show how much GW corrections are important not only for the band structure but also in the calculation of the electron-phonon matrix elements. I present different examples and comparison with the experimental results.
Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of el...Sérgio Sacani
High-energy cosmic-ray electrons and positrons (CREs), which
lose energy quickly during their propagation, provide a probe of
Galactic high-energy processes1–7 and may enable the observation
of phenomena such as dark-matter particle annihilation or
decay8–10. The CRE spectrum has been measured directly up to
approximately 2 teraelectronvolts in previous balloon- or spaceborne
experiments11–16, and indirectly up to approximately 5
teraelectronvolts using ground-based Cherenkov γ-ray telescope
arrays17,18. Evidence for a spectral break in the teraelectronvolt
energy range has been provided by indirect measurements17,18,
although the results were qualified by sizeable systematic
uncertainties. Here we report a direct measurement of CREs in the
energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the
Dark Matter Particle Explorer (DAMPE)19 with unprecedentedly
high energy resolution and low background. The largest part of
the spectrum can be well fitted by a ‘smoothly broken power-law’
model rather than a single power-law model. The direct detection of
a spectral break at about 0.9 teraelectronvolts confirms the evidence
found by previous indirect measurements17,18, clarifies the behaviour
of the CRE spectrum at energies above 1 teraelectronvolt and sheds
light on the physical origin of the sub-teraelectronvolt CREs.
P-Wave Onset Point Detection for Seismic Signal Using Bhattacharyya DistanceCSCJournals
In seismology Primary p-wave arrival identification is a fundamental problem for the geologist worldwide. Several numbers of algorithms that deal with p-wave onset detection and identification have already been proposed. Accurate p- wave picking is required for earthquake early warning system and determination of epicenter location etc. In this paper we have proposed a novel algorithm for p-wave detection using Bhattacharyya distance for seismic signals. In our study we have taken 50 numbers of real seismic signals (generated by earthquake) recorded by K-NET (Kyoshin network), Japan. Our results show maximum standard deviation of 1.76 sample from true picks which gives better accuracy with respect to ratio test method.
Enzo palmieri the problem of heat transfer at liquid helium temperatures 1st...thinfilmsworkshop
For decades the attention of Scientists working on the performance improvement of superconducting cavities has been focused onto the study of the cavity interior and more precisely to the optimization of the first hundreds nanolayers of the Niobium surface exposed to the electromagnetic fields. In the meantime, little attention has been played to the status of the external surface in contact with liquid Helium. In our analysis we will see that both from the literature analysis and from the experimental results, the status of the cavity external surface has a non-negligible importance.
I show how much GW corrections are important not only for the band structure but also in the calculation of the electron-phonon matrix elements. I present different examples and comparison with the experimental results.
Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of el...Sérgio Sacani
High-energy cosmic-ray electrons and positrons (CREs), which
lose energy quickly during their propagation, provide a probe of
Galactic high-energy processes1–7 and may enable the observation
of phenomena such as dark-matter particle annihilation or
decay8–10. The CRE spectrum has been measured directly up to
approximately 2 teraelectronvolts in previous balloon- or spaceborne
experiments11–16, and indirectly up to approximately 5
teraelectronvolts using ground-based Cherenkov γ-ray telescope
arrays17,18. Evidence for a spectral break in the teraelectronvolt
energy range has been provided by indirect measurements17,18,
although the results were qualified by sizeable systematic
uncertainties. Here we report a direct measurement of CREs in the
energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the
Dark Matter Particle Explorer (DAMPE)19 with unprecedentedly
high energy resolution and low background. The largest part of
the spectrum can be well fitted by a ‘smoothly broken power-law’
model rather than a single power-law model. The direct detection of
a spectral break at about 0.9 teraelectronvolts confirms the evidence
found by previous indirect measurements17,18, clarifies the behaviour
of the CRE spectrum at energies above 1 teraelectronvolt and sheds
light on the physical origin of the sub-teraelectronvolt CREs.
P-Wave Onset Point Detection for Seismic Signal Using Bhattacharyya DistanceCSCJournals
In seismology Primary p-wave arrival identification is a fundamental problem for the geologist worldwide. Several numbers of algorithms that deal with p-wave onset detection and identification have already been proposed. Accurate p- wave picking is required for earthquake early warning system and determination of epicenter location etc. In this paper we have proposed a novel algorithm for p-wave detection using Bhattacharyya distance for seismic signals. In our study we have taken 50 numbers of real seismic signals (generated by earthquake) recorded by K-NET (Kyoshin network), Japan. Our results show maximum standard deviation of 1.76 sample from true picks which gives better accuracy with respect to ratio test method.
Resonant-tunneling-diode effect in Si-based double-barrier structure sputtere...IJRES Journal
This paper presents the resonant-tunneling-diode (RTD) effect in a SiO2/n-Si/SiO2/p-Si double-barrier structural thin films fabricated using radio frequency (RF) magnetron sputtering at room temperature (300 K). The implementation of a circuit prototype is first accomplished by modulating a Si-based RTD with a solar-cell bias voltage. The important electrical properties of the peak current density and peak-to-valley current ratio (PVCR) are 184 nA/cm2 and 1.67, respectively. The connection between the two RTDs in series is biased by a solar cell. The value of the switching transition time is 24.37 μs; oscillation occurs with an operating frequency of 41.6 KHz. In semiconductor applications, the developed RTD is characterized by stability, enduring environmentally elevated temperature and relative humidity.
2019-06-07 Characterization and research of semiconductors with an FTIR spect...LeonidBovkun
2019-06-07 Educational seminar at EP-3 University of Wuerzburg
I will present particular experiments and related results with FTIR spectrometer, so one may consider these experiments complimentary for you research.
Application of Dielectric Spectroscopy to Monitor Insulating Materials ahmdfurkan
PDC measurements, it was found that polarization and depolarization currents increase with temperature increase. Also, the shape of polarization current changes as temperature increases
Drying of the transformer shows a significant reduction of the polarization/depolarization currents.
Moisture and aging have great effect on dielectric response of oil-paper insulation in frequency domain both of them will cause the increase of tan δ
Diagnostics of oil-paper insulation based on Frequency Domain Spectroscopy has great advantage over traditional techniques for its simple operation and non-destructive
La Previsione del tempo atmosferico dal paradigma deterministico a quello pro...nipslab
La Previsione del tempo atmosferico dal paradigma deterministico a quello probabilistico
Ten.Marcucci Francesca
Centro Nazionale Meteorologia e Climatologia Aeronautica
1. Universita’ di Perugia 15 Aprile 2010 Ruolo delle correlazioni superconduttive in conduttori mesoscopici: utilizzo per l’implementazione di rilevatori quantistici Francesco Giazotto NEST Istituto Nanoscienze-CNR & Scuola Normale Superiore Pisa, Italia
2. Collaboration J. T. Peltonen M. Meschke J. P. Pekola Low Temperature Laboratory, Helsinki University of Technology, 02015TKK, Finland
3.
4. Andreev reflection in SN contacts BdG equations Andreev reflection BTK, PRB 25 , 4515 (1982)
5. Proximity effect and supercurrent S S N Metallic contact between a normal metal and a superconductor S S N Electron-hole correlations: proximity effect Supercurrent Andreev bound states (ABS) Reflected hole Incident electron Superconductor Normal metal (Semiconductor) Cooper pair Andreev reflection
6. Proximity effect in SNS systems: basic formalism LDOS properties: N (- E ) = N ( E ) E g for | E | E g E g ( = 0) 3.2 E Th for >> E Th E g ( = ) = 0 Diffusive mesoscopic N wire: quasi-1D geometry L >L >> l e D = diffusion coefficient = superconducting order parameter = macroscopic phase of the order parameter E Th = D/L 2 Thouless energy Usadel equations LDOS
7. Modification of the LDOS in SNS systems due to proximity effect J. C. Hammer et al ., PRB 76 , 064514 (2007) Phase dependence J. C. Cuevas et al ., PRB 73 , 184505 (2006) Length and position dependence
8. Spatial spectroscopy of PE probed with tunnel junctions Al/Cu SN structure with tunnel probes
10. Phase-dependence of PE probed with STM spectroscopy Experiment to theory comparison H. le Sueur et al ., PRL 100 , 197002 (2008) Phase-evolution of PE Full phase-control of the minigap amplitude
11. I) -tuning of specific heat: quantum control of a thermodynamic variable H. Rabani, F. Taddei, F. G. and R. Fazio, JAP 105 , 093904 (2009); H. Rabani, F. Taddei, R. Fazio, and F. G., PRB 78, 012503 (2008) Electron entropy Electron specific heat
12. II) -tuning of e-ph interaction: quantum control of relaxation T. T. Heikkila and F. G., PRB 79 , 094514 (2009)
14. SQUIPT: a novel quantum interferometer Active manipulation of the DOS of a proximity N metal Phase control (through magnetic flux) Detection (through tunnel junctions) High sensitivity for flux detection SQUIPT
15. SQUIPT: fabrication details and configurations Shadow-mask evaporation 27 nm Al @ 25 Oxidation 4.4 mbar 5’ (tunnel junctions) 27 nm Cu @ -25 60 nm Al @ 60 (clean SN interfaces) Fabrication details Geometry and materials details L 1.5 m Probe width 200 nm N wire width 240 nm SN overlapping 250 nm R t 50-70 k L G 40 pH I J 3 A = 200 eV
16. SQUIPT (theo): prediction of its behavior in the current-bias mode A-type configuration Usadel equations quasiparticle current
17.
18.
19. A-type SQUIPT (exp): current-voltage characteristic vs R t = 50 k T = 68 mK Coherent modulation of the N DOS R t = 50 k T = 53 mK Theory
20. A-type SQUIPT (exp): Josephson coupling in the proximity metal R t = 50 k T = 68 mK I J 17 pA R t = 50 k T = 53 mK 0 0.17 Oe A 120 m 2
21.
22. A-type SQUIPT (exp): transfer function R t = 50 k T = 54 mK V / 30 V/ 0 @ 1 nA theory
23. B-type SQUIPT (exp): voltage modulation vs and transfer function R t = 70 k T = 53 mK V 12 V @ 1 nA V / 60 V/ 0 @ 0.6 nA R t = 70 k T = 53 mK doubled response in B-type SQUIPT
24. A-type SQUIPT (exp): temperature dependence R t = 50 k I = 1 nA R t = 50 k I = 1 nA change of concavity between 376 mK and 411 mK
25. SQUIPT: dissipation and flux sensitivity Power dissipation P diss = VI 100 fW increasing the probing junction resistance lowered DC SQUIDS 4-5 orders of magnitude smaller in the SQUIPT Ultralow dissipation cryogenic applications Flux sensitivity NEF = <V 2 N > 1/2 /| V/ | 1/2 N Pre 1.2 nV/Hz 1/2 NEF 2 10 -5 0 /Hz 1/2 NEF 4 10 -7 0 /Hz 1/2 with Nb ( 1.5 meV) and L = 150 nm
26.
27. SQUIPT: future perspectives Short junction limit ( << E Th ) Al and L = 150 nm (i) (ii) V SNS junction SQUIPT C. Pascual Garcia and F. G., APL 94 , 132508 (2009) (iii) Noise? Both theory and experiment