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Quantum Computer

Quantum Computer

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  • 1. Quantum Computer By Ritikesh Bhaskarwar Department of ComputerTechnology YESHWANTRAO CHAVAN COLLEGE OF ENGINEERING, Nagpur (An Autonomous Institution Affiliated to RashtrasantTukadoji Maharaj Nagpur University)
  • 2. Introduction :  A quantum computer is a device for computation that makes direct use of quantum mechanical phenomena, such as superposition and entanglement, to perform operations on data.  It harnesses the power of atoms and molecules to perform memory and processing tasks.
  • 3.  If, as Moore's Law states, the number of transistors on a microprocessor continues to double every 18 months, the year 2020 or 2030 will find the circuits on a microprocessor measured on an atomic scale.  The logical next step will be to create quantum computers, which will harness the power of atoms and molecules to perform memory and processing tasks.
  • 4. History :  Richard Feynman observed in the early 1980s [Feynman 1982] that certain quantum mechanical effects cannot be simulated efficiently on a classical computer.  It wasn’t until 1994, when Peter Shor surprised the world by describing a polynomial time quantum algorithm for factoring integers [Shor 1994; 1997]
  • 5. Literature Survey:  E.Rieffel,W.Polak,”An IntroductionTo Quantum Computing for Non-Physicist”, ACM Computing Survey,Vol. 32, No.3 (2000). => It introduces basic principles of quantum mechanics to explain where the power of quantum computers comes from and why it is difficult to harness.
  • 6.  D.DiVincenzo, ”Quantum Computation”, Science, New Series,Vol. 270, No.5234 (2006). => It is evident from this survey of the current state of art in quantum experimental physics that construction of quantum computer is presently in most rudimentary stage.  C.H.Bennet, ”Quantum Information And Computation”, Physics Today, American Institute of Physics (1995). => The quantum information processing involves quantum states which is described by a wave function or a state in a Hilbert space
  • 7. Background Knowledge :  Superposition Definition :- Two things can overlap each other without interfering with each other. In classical computers, electrons cannot occupy the same space at the same time, but as waves, they can.  A single qubit can be forced into a superposition of the two states denoted by the addition of the state vectors:
  • 8. A qubit in superposition is in both of the states |1> and |0> at the same time Superposition
  • 9.  Entanglement  Entanglement is the ability of quantum systems to exhibit correlations between states within a superposition.  Imagine two qubits, each in the state |0> + |1> (a superposition of the 0 and 1.) We can entangle the two qubits such that the measurement of one qubit is always correlated to the measurement of the other qubit.
  • 10. Quantum Bits:  A quantum bit, or qubit, is a unit vector in a two-dimensional complex vector space for which a particular basis, denoted by {|0>,|1>}, has been fixed.  The orthonormal basis |0> and |1> may correspond to the |↑> and |→> polarizations of a photon respectively
  • 11. Pictorial Representation of Qubits State |0> (top) and State |1> (bottom)
  • 12. Bits v/s Qubits Bits Qubits  The device computes by manipulating those bits with the help of logic gates  A classical computer has a memory made up of bits , where each bit holds either a one or a zero  A qubit can hold a one, a zero, or, crucially, a superposition of these ,manipulating those qubits with the help of quantum logic gates  The qubits can be in a superposition of all the classically allowed states.
  • 13. Basic building block of quantum computer
  • 14. Quantum Dots :  A quantum dot is a semiconductor nanostructure that confines the motion of conduction band electrons valence band holes or excitons (pairs of conduction band electrons and valence band holes) ,in all three spatial directions.
  • 15. UNIVERSAL QUANTUM LOGIC GATE  It is realized with high-finesse microwave cavities and two-state atoms.  All possible quantum computations can be built up with a network of such gates.  More general output states can be obtained by adjusting the atom-cavity interactions and adding another Ramsey zone
  • 16. Quantum Logic Gate :
  • 17. Advantages :  Exponential computing power, combined with the fact that a qubit can be simultaneously a one and zero at the same time, gives quantum computers another edge over binary.  It can explore different solutions simultaneously, instead of one at a time. Imagine having thousands of computers working in unison to solve your problem.
  • 18.  They can cut the amount of time needed to find a solution by well over half, reducing a problem that might have taken years to solve to mere hours.  In quantum systems, the computational space increases exponentially with the size of the system, which enables exponential parallelism.  The exploitation of the properties such as entanglement and superposition permit some types of computations to be performed more efficiently than the best competing classical algorithms.
  • 19. Limitations :  One of the major problems of quantum computers is that the interaction between qubits cannot be turned on and off when desired.  While a quantum system can perform massive parallel computation, access to the results of the computation is restricted. Accessing the results is equivalent to making a measurement, which disturbs the quantum state.
  • 20. Realizations and difficulty in building quantum computer The quantum computer might be the theoretician's dream, its realization is a nightmare  It is very difficult to scaling the component in quantum computer As the number of quantum gates in a network increases, we quickly run into some serious practical problems The more likely it is that quantum information will spread outside the quantum computer and be lost into the environment, thus spoiling the computation
  • 21. Application :  Quantum computing is currently being used for encryption, long calculations and most importantly software validation.  As technology reaches every aspect of living, having error free code is indispensable and a quantum computer is the perfect solution for testing and validating software code as quantum computers solve problems in a more probabilistic manner.  Immense amount of computing power leads to calculate impossible mathematical calculation. Quantum computation algorithm has great application in the field of Mathematics.  It has wide application in cryptography (the method of breaking ciphers).
  • 22. Conclusion :  It discusses an overview of the quantum computing world.  It discusses the inevitability of quantum computers, how they originated, and what is different about them from classical computers.  Quantum computes are coming, and they will require a new way of looking at computing.
  • 23. Reference :  E.Rieffel,W.Polak,”An IntroductionTo Quantum Computing for Non-Physicist”,ACM Computing Survey,Vol. 32, No.3 (2000).  C.H.Bennet,”Quantum Information And Computation”, PhysicsToday,American Institute of Physics (1995).  M.Lanzagorta, J.Uhlmann,”Hybrid Quantum- Classical Computing with Application to Computer Graphics”, IEEE Computer Graphics with Application (2003).