We investigate the quantum speed limit time （QSLT） of a two-level atom under quantum-jump-based feedback control or homodyne-based feedback control. Our results show that the two different feedback control schemes h...We investigate the quantum speed limit time （QSLT） of a two-level atom under quantum-jump-based feedback control or homodyne-based feedback control. Our results show that the two different feedback control schemes have different influences on the evolutionary speed. By adjusting the feedback parameters, the quantum-jump-based feedback control can induce speedup of the atomic evolution from an excited state, but the homodyne-based feedback control cannot change the evolutionary speed. Additionally, the QSLT for the whole dynamical process is explored. Under the quantum-jump-based feedback control, the QSLT displays oscillatory behaviors, which implies multiple speed-up and speed-down processes during the evolution. While, the homodyne-based feedback control can accelerate the speed-up process and improve the uniform speed in the uniform evolution process.展开更多
A scheme is proposed to controll the decoherence of three-level rf-SQUID qubit with asymmetric potential by designing an external electric circuit for superconductive flux qubit. The results show that it may not only ...A scheme is proposed to controll the decoherence of three-level rf-SQUID qubit with asymmetric potential by designing an external electric circuit for superconductive flux qubit. The results show that it may not only raise the gate speed but also extend decoherence time for a three-level structure.展开更多
We study the optimal quantum control of heteronuclear two-qubit systems described by a Hamiltonian containing both nonlocal internal drift and local control terms.We derive an explicit formula to compute the minimum t...We study the optimal quantum control of heteronuclear two-qubit systems described by a Hamiltonian containing both nonlocal internal drift and local control terms.We derive an explicit formula to compute the minimum time required to steer the system from an initial state to a specified final state.As applications the minimal time to implement Controlled-NOT gate,SWAP gate and Controlled-U gate is calculated in detail.The experimental realizations of these quantum gates are explicitly presented.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11374096)Hunan Provincial Innovation Foundation for Postgraduate,China(Grant No.CX2017B177)the Scientific Research Project of Hunan Provincial Education Department,China(Grant No.16C0949)
文摘We investigate the quantum speed limit time （QSLT） of a two-level atom under quantum-jump-based feedback control or homodyne-based feedback control. Our results show that the two different feedback control schemes have different influences on the evolutionary speed. By adjusting the feedback parameters, the quantum-jump-based feedback control can induce speedup of the atomic evolution from an excited state, but the homodyne-based feedback control cannot change the evolutionary speed. Additionally, the QSLT for the whole dynamical process is explored. Under the quantum-jump-based feedback control, the QSLT displays oscillatory behaviors, which implies multiple speed-up and speed-down processes during the evolution. While, the homodyne-based feedback control can accelerate the speed-up process and improve the uniform speed in the uniform evolution process.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10864002)
文摘A scheme is proposed to controll the decoherence of three-level rf-SQUID qubit with asymmetric potential by designing an external electric circuit for superconductive flux qubit. The results show that it may not only raise the gate speed but also extend decoherence time for a three-level structure.
基金supported by the National Natural Science Foundation of China(Grant No.11275131)the National Research Foundation for the Doctoral Program of Higher Education of China
文摘We study the optimal quantum control of heteronuclear two-qubit systems described by a Hamiltonian containing both nonlocal internal drift and local control terms.We derive an explicit formula to compute the minimum time required to steer the system from an initial state to a specified final state.As applications the minimal time to implement Controlled-NOT gate,SWAP gate and Controlled-U gate is calculated in detail.The experimental realizations of these quantum gates are explicitly presented.
