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Quantum Entanglement and Quantum Computation in Solid-state Spin Systems

Author: HaoXiang
Tutor: ZhuShiQun
School: Suzhou University
Course: Optical Engineering
Keywords: Quantum entanglement Quantum computing Solid - state spin system Quantum information processing Master equation
CLC: O413.1
Type: PhD thesis
Year: 2008
Downloads: 193
Quote: 1
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Abstract


This paper studies the characteristics of quantum entanglement in the one-dimensional solid-state spin system, thermal entanglement exists and the ground state entanglement conditions by different criteria. Departure from the essence of quantum entanglement, the critical behavior of the ground state of the many-body quantum systems. Typical solid-state spin system applied to quantum information processing, viable quantum computing, and analyze the impact of the physical environment of quantum computing. This article is based on the definition of quantum entanglement, measurable physical quantities to construct effective entanglement criterion. By these criteria, we have studied the entanglement properties of one-dimensional solid-state spin chain, such as: Heisenberg chain of arbitrary spin, mixed spin chain and solid boson Hubbard chain. Among them, we get the critical temperature of the thermal entanglement. When the physical temperature of the system is less than this value, the corresponding thermal equilibrium state is entangled, but as the temperature rises, it is gradually disappear. We put these the Criterion theoretical discriminant method compares these criterion based on measurable physical quantities entanglement exists a sufficient condition. The numerical results show that the spin system with a large number of particles, when the lower temperature, the experiments can also be detected entangled state. For the many-body quantum systems, this paper focuses on the multi-body and two-body ground state entanglement, to find the global entanglement and quantum phase transition contact, and found that the actual solid-state spin system, the two-body entangled than many-body entangled easier to exist. In order to consider the actual environmental impact of quantum entanglement, this article by the master equation analysis of quantum states with the evolution of the small number of atoms in a vacuum thermal library. When only one atom in an excited state, who was originally in the ground state atom quantum entanglement occurs. Entangled size changes over time similar to the Rabi oscillation damping, the amplitude is limited by the atomic spontaneous decay intensity modulation. Through the accurate solving quantum states of the system, we have the produce entanglement physical mechanisms. The results show that entanglement exists mainly depends on the excitation state and the ground state transition probabilities between different atoms. The article also discusses the solid-state spin-based quantum computing solutions. In order to make the system model is closer to the actual situation, we have a strong focus on non-uniform and non-symmetric exchange interaction. Evolution which we analytically qubit states containing quantum swap gate Heisenberg XXZ model physical conditions, analysis of the impact of quantum computing, quantum fluctuations within the system, given available operation of the experimental program. Non-symmetry of the interaction of coupled electron spins in semiconductor quantum dots, the use of single-qubit rotation operation to construct a two-qubit CNOT, in order to achieve a higher precision of quantum computing. Solid-state spin system in order to achieve quantum information processing in the experiment, and the need to overcome the difficulties of operating short distance. We put forward the theory of coupled spin chains as quantum computing bus program, when the bus system has been in a non-degenerate ground state, the use of electrodes to control the number of qubits weakly coupled to their produce, so that we can indirectly qubit effective long-range interactions. On this basis, we construct a set of universal quantum gate, in order to achieve the purpose of long-range quantum computing.

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CLC: > Mathematical sciences and chemical > Physics > Theoretical Physics > Quantum theory > Quantum mechanics ( wave mechanics,matrix mechanics )
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