Optical nonreciprocal transmission with unidirectional amplification in a gain-assisted cavity-QED system is investigated.The results demonstrate that unidirectional amplification of this system is induced by the phas...Optical nonreciprocal transmission with unidirectional amplification in a gain-assisted cavity-QED system is investigated.The results demonstrate that unidirectional amplification of this system is induced by the phase difference between the atom-cavity coupling strengths associated with the optical gain and a phase-controlled unidirectional amplifier can be achieved.The optimal parameter conditions for the observation of ideal unidirectional amplification are obtained analytically,and are shown to be dependent on phase,atom-cavity and cavity-cavity coupling strength,and atomic dissipation.In particular,it is found that atomic dissipation is another essential condition for the realization of nonreciprocal amplification other than breaking of the time-reversal symmetry,and our unidirectional amplifier is robust against atom-cavity coupling mismatch.Such unidirectional amplifiers are crucial nonreciprocal devices for controlling photon transmission and may have potential applications in quantum information processing.展开更多
Coherent perfect absorption(CPA)and coherent perfect transmission(CPT)are two extreme states arising from the manipulation of optical fields.Generally,CPA and CPT occur under different input-field phases.Therefore,we ...Coherent perfect absorption(CPA)and coherent perfect transmission(CPT)are two extreme states arising from the manipulation of optical fields.Generally,CPA and CPT occur under different input-field phases.Therefore,we propose a scheme to realize an all-optical switch based on phase-dependent CPA–CPT conversion.In our proposal,the CPT state and the CPA state are treated as the on state and the off state,respectively.Consequently,the efficiency of this all-optical switch can reach the maximum value of 1.With the introduction of an incoherent pump field,the CPA state can be achieved under a weaker input probe field or can be converted into a CPT state.The results show that the optical switch can operate with weaker fields and can be further optimized by the application of an incoherent field.展开更多
We propose a scheme to implement the optimal symmetric 1 → 2 universal quantum telecloning through cavity-assisted interaction. In our scheme an arbitrary single atomic state can be telecloned to two single atomic st...We propose a scheme to implement the optimal symmetric 1 → 2 universal quantum telecloning through cavity-assisted interaction. In our scheme an arbitrary single atomic state can be telecloned to two single atomic states. And three atoms are trapped in three spatially separated cavities respectively. With a particular multiparticle entangled state acting as a quantum information channel and the trapped single atom acting as a quantum network node for its long-lived internal state, quantum information can be telecloned among nodes and can stored in the nodes.展开更多
To implement generalized quantum measurement （GQM） one has to extend the original Hilbert space. Generally speaking, the additional dimensions of the ancilla space increase as the number of the operators of the GQM ...To implement generalized quantum measurement （GQM） one has to extend the original Hilbert space. Generally speaking, the additional dimensions of the ancilla space increase as the number of the operators of the GQM n increases. This paper presents a scheme for deterministically implementing all possible n-operator CQMs on a single atomic qubit by using only one 2-dimensional ancillary atomic qubit repeatedly, which remarkably reduces the complexity of the realistic physical system. Here the qubit is encoded in the internal states of an atom trapped in an optical cavity and single-photon pulses are employed to provide the interaction between qubits. It shows that the scheme can be performed remotely, and thus it is suitable for implementing CQM in a quantum network. What is more, the number of the total ancilla dimensions in our scheme achieves the theoretic low bound.展开更多
We present a scheme to realize geometric phase-shift gate for two superconducting quantum interference device （SQUID） qubits coupled to a single-mode microwave field. The geometric phase-shift gate operation is perf...We present a scheme to realize geometric phase-shift gate for two superconducting quantum interference device （SQUID） qubits coupled to a single-mode microwave field. The geometric phase-shift gate operation is performed in two lower flux states, and the excited state [2〉 would not participate in the procedure. The SQUIDs undergo no transitions during the gate operation. Thus, the docoherence due to energy spontaneous emission based on the levels of SQUIDs are suppressed. The gate is insensitive to the cavity decay throughout the operation since the cavity mode is displaced along a circle in the phase space, acquiring a phase conditional upon the two lower flux states of the SQUID qubits, and the cavity mode is still in the original vacuum state. Based on the SQUID qubits interacting with the cavity mode, our proposed approach may open promising prospects for quantum iogic in SQUID-system.展开更多
基金supported by China Postdoctoral Science Foundation(2023M732028)Zhejiang Province Key Laboratory of Quantum Technology and Device(20230201)+1 种基金National Key Research and Development Program of China(2021YFA1400602)National Natural Science Foundation of China(11864018,12164022,12174288,12274326)。
文摘Optical nonreciprocal transmission with unidirectional amplification in a gain-assisted cavity-QED system is investigated.The results demonstrate that unidirectional amplification of this system is induced by the phase difference between the atom-cavity coupling strengths associated with the optical gain and a phase-controlled unidirectional amplifier can be achieved.The optimal parameter conditions for the observation of ideal unidirectional amplification are obtained analytically,and are shown to be dependent on phase,atom-cavity and cavity-cavity coupling strength,and atomic dissipation.In particular,it is found that atomic dissipation is another essential condition for the realization of nonreciprocal amplification other than breaking of the time-reversal symmetry,and our unidirectional amplifier is robust against atom-cavity coupling mismatch.Such unidirectional amplifiers are crucial nonreciprocal devices for controlling photon transmission and may have potential applications in quantum information processing.
基金supported by the National Natural Science Foundation of China(Grants Nos.12304405,12275203,and 12075176)the Natural Science Foundation of Shaanxi Provincial Department of Education(Grant No.23JK0483)+2 种基金the Natural Science Basic Research Program of Shaanxi(Grant Nos.2024JC-YBMS-521 and 2024JC-YBMS-039)the 2022 Shaanxi University Youth Innovation Team Project(Grant No.K20220186)the College Students’Innovative Entrepreneurial Training Plan Program of Shaanxi(Grant No.S202410702178)。
文摘Coherent perfect absorption(CPA)and coherent perfect transmission(CPT)are two extreme states arising from the manipulation of optical fields.Generally,CPA and CPT occur under different input-field phases.Therefore,we propose a scheme to realize an all-optical switch based on phase-dependent CPA–CPT conversion.In our proposal,the CPT state and the CPA state are treated as the on state and the off state,respectively.Consequently,the efficiency of this all-optical switch can reach the maximum value of 1.With the introduction of an incoherent pump field,the CPA state can be achieved under a weaker input probe field or can be converted into a CPT state.The results show that the optical switch can operate with weaker fields and can be further optimized by the application of an incoherent field.
基金supported by National Natural Science Foundation of China under Grant No.10674001the Program of the Education Department of Anhui Province under Grant No.KJ2007A002the Youth Program of Fu Yang Normal College under Grant No.2008LQ04
文摘We propose a scheme to implement the optimal symmetric 1 → 2 universal quantum telecloning through cavity-assisted interaction. In our scheme an arbitrary single atomic state can be telecloned to two single atomic states. And three atoms are trapped in three spatially separated cavities respectively. With a particular multiparticle entangled state acting as a quantum information channel and the trapped single atom acting as a quantum network node for its long-lived internal state, quantum information can be telecloned among nodes and can stored in the nodes.
基金supported by the National Natural Science Foundation of China (Grant No 10774192)the Fund of Innovation of the Graduate School of National University of Defense Technology (Grant No B080201)
文摘To implement generalized quantum measurement （GQM） one has to extend the original Hilbert space. Generally speaking, the additional dimensions of the ancilla space increase as the number of the operators of the GQM n increases. This paper presents a scheme for deterministically implementing all possible n-operator CQMs on a single atomic qubit by using only one 2-dimensional ancillary atomic qubit repeatedly, which remarkably reduces the complexity of the realistic physical system. Here the qubit is encoded in the internal states of an atom trapped in an optical cavity and single-photon pulses are employed to provide the interaction between qubits. It shows that the scheme can be performed remotely, and thus it is suitable for implementing CQM in a quantum network. What is more, the number of the total ancilla dimensions in our scheme achieves the theoretic low bound.
基金The project supported by the National Natural Science Foundation of China under Grant No. 10574126.
文摘We present a scheme to realize geometric phase-shift gate for two superconducting quantum interference device （SQUID） qubits coupled to a single-mode microwave field. The geometric phase-shift gate operation is performed in two lower flux states, and the excited state [2〉 would not participate in the procedure. The SQUIDs undergo no transitions during the gate operation. Thus, the docoherence due to energy spontaneous emission based on the levels of SQUIDs are suppressed. The gate is insensitive to the cavity decay throughout the operation since the cavity mode is displaced along a circle in the phase space, acquiring a phase conditional upon the two lower flux states of the SQUID qubits, and the cavity mode is still in the original vacuum state. Based on the SQUID qubits interacting with the cavity mode, our proposed approach may open promising prospects for quantum iogic in SQUID-system.
