Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province

Nanchang, China

Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province

Nanchang, China

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Ji Y.-H.,Jiangxi Normal University | Ji Y.-H.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province | Hu J.-J.,Jiangxi Normal University | Hu J.-J.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province
Chinese Physics B | Year: 2014

We demonstrate the controllable generation of multi-photon Fock states in circuit quantum electrodynamics (circuit QED). The external bias flux regulated by a counter can effectively adjust the bias time on each superconducting flux qubit so that each flux qubit can pass in turn through the circuit cavity and thereby avoid the effect of decoherence. We further investigate the quantum correlation dynamics of coupling superconducting qubits in a Fock state. The results reveal that the lower the photon number of the light field in the number state, the stronger the interaction between qubits is, then the more beneficial to maintaining entanglement between qubits it will be. © 2014 Chinese Physical Society and IOP Publishing Ltd.


Ke Q.,Jiangxi Normal University | Ke Q.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province
Advanced Materials Research | Year: 2013

A chaos communication system in semiconductor lasers is proposed. Based on the idea of drive-response synchronization, taking the one-way coupled external cavity semiconductor laser with feedback system as an example, we discuss the principle, numerical simulation of chaotic synchronization and analyze the laser parameter mismatch on the synchronization performance. © (2013) Trans Tech Publications, Switzerland.


Ji Y.-H.,Jiangxi Normal University | Ji Y.-H.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province | Liu Y.-M.,Jiangxi Normal University
Chinese Physics B | Year: 2014

Although the multi-level structure of superconducting qubits may result in calculation errors, it can be rationally used to effectively improve the speed of gate operations. Utilizing a current-biased Josephson junction (λ-type rf-SQUID) as a tunable coupler for superconducting transmission line resonators (TLRs), under the large detuning condition, we demonstrate the controllable generation of entangled coherent states in circuit quantum electrodynamics (circuit QED). The coupling between the TLRs and the qubit can be effectively regulated by an external bias current or coupling capacitor. Further investigations indicate that the maximum entangled state can be obtained through measuring the excited state of the superconducting qubits. Then, the influence of the TLR decay on the prepared entangled states is analyzed. © 2014 Chinese Physical Society and IOP Publishing Ltd.


Ying-Hua J.,Jiangxi Normal University | Ying-Hua J.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province | Yong-Mei L.,Jiangxi Normal University
International Journal of Theoretical Physics | Year: 2016

Dynamical evolutions of quantum correlations in circuit quantum electrodynamics (circuit-QED) are investigated under various dissipative modes. The influences of photon number, coupling strength, detuning and relative phase angle on quantum entanglement and quantum discord are compared as well. The results show that quantum discord may be less robust to decoherence than quantum entanglement since the death and revival also appears. Under certain dissipative mode, the decoherence subspace can be formed in circuit-QED due to the cooperative action of vacuum field. Whether a decoherence subspace can be formed not only depends on the form of quantum system but also relates closely to the dissipative mode of environment. One can manipulate decoherence through manipulating the correlation between environments, but the effect depends on the choice of initial quantum states and dissipative modes. Furthermore, we find that proper relative phase of initial quantum state provides one means of suppressing decoherence. © 2016 Springer Science+Business Media New York


Ji Y.-H.,Jiangxi Normal University | Ji Y.-H.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province
Chinese Physics B | Year: 2015

Super-quantum discord (SQD) with weak measurement is regarded as a kind of quantum correlation in quantum information processing. We compare and analyze the dynamical evolutions of SQD, quantum discord (QD), and quantum entanglement (QE) between two qubits in the correlated dephasing environmental model. The results indicate that (i) owing to the much smaller influence of weak measurement on the coherence of the system than that of von Neumann projection measurement, SQD with weak measurement is larger than QD, and (ii) dynamical evolution of QD or QE monotonically goes to zero with time, while SQD monotonically tends to a stable value and a freezing phenomenon occurs. The stable value after freezing mainly depends on the measurement strength and the purity of the initial quantum state. © 2015 Chinese Physical Society and IOP Publishing Ltd.


Hu J.-J.,Jiangxi Normal University | Li S.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province
Communications in Theoretical Physics | Year: 2014

The dynamics of entanglement between two qubits in the local damping two-sided channel and single-sided channel are compared through non-Markovian process and Markovian process. The entanglement between two qubits is found to be longer in the single-sided channel case due to the weakening of the dissipative effects. In the two-sided channel, influenced by the entanglement between qubits, the previous independent dissipative channels incline to the composite effect of the Markovian process. This composite effect results in the dissipative effect of one channel affecting the qubits in the other channel, especially inhibiting the backflow effect in the non-Markovian channel, which is disadvantageous to the entanglement maintenance between qubits. In the Markovian channel, the composite effect of the damping two-sided channels is more obvious since there is no backflow effect, thus more disadvantageous to the entanglement maintenance. © 2014 Chinese Physical Society and IOP Publishing Ltd.


Ji Y.-H.,Jiangxi Normal University | Ji Y.-H.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province | Liu Y.-M.,Jiangxi Normal University
International Journal of Theoretical Physics | Year: 2013

We investigate the dynamic evolution behaviors of entanglement and geometric quantum discord (GQD) of hybrid qubits in a circuit QED system. Under certain initial conditions, interactions between qubits and that between the qubit and the cavity can suppress the decay of entanglement and GQD of qubits. Under the initial condition {pipe}ψ Q(0)〉I=sinα{pipe}↓↑〉+cosα{pipe}↑↓〉, such decay was avoided by increasing the coupling strength ratio between qubits and that between the qubit and the cavity. Under the aforementioned condition, the survival time of entanglement and GQD was prolonged by decreasing the coupling strength ratio between qubits and that between the qubit and the cavity. © 2013 Springer Science+Business Media New York.


Ke Q.,Jiangxi Normal University | Ke Q.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province
Advanced Materials Research | Year: 2013

Using the idea of drive-response synchronization, we discuss the principle, numerical simulation of chaotic laser communication. Compared to traditional communications systems, the chaotic laser communication system has a well-kept secret performance, but the chaos synchronization requirements are very strict. © (2013) Trans Tech Publications, Switzerland.


Ji Y.-H.,Jiangxi Normal University | Ji Y.-H.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province | Liu Y.-M.,Jiangxi Normal University
Chinese Physics B | Year: 2013

In this paper, we investigate the quantum correlation of coupled qubits which are initially in maximally entangled mixed states in a squeezed vacuum reservoir. We compare and analyze the effects of squeezed parameters on quantum discord and quantum concurrence. The results show that in a squeezed vacuum reservoir, the quantum discord and quantum concurrence perform with completely opposite behaviors with the change of squeezed parameters. Quantum discord survives longer with the increase of squeezed amplitude parameter, but entanglement death is faster on the contrary. The results also indicate that the classical correlation of the system is smaller than quantum discord in a vacuum reservoir, while it is bigger than quantum discord in a squeezed vacuum reservoir. The quantum discord and classical correlation are more robust than quantum concurrence in the two reservoir environments, which indicates that the entanglement actually is easily affected by decoherence and quantum discord has a stronger ability to avoid decoherence in a squeezed vacuum reservoir. © 2013 Chinese Physical Society and IOP Publishing Ltd.


Ji Y.-H.,Jiangxi Normal University | Ji Y.-H.,Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province | Hu J.-J.,Jiangxi Normal University | Hu Y.,Jiangxi Normal University
Chinese Physics B | Year: 2012

We investigate the influence of environmental decoherence on the dynamics of a coupled qubit system and quantum correlation. We analyse the relationship between concurrence and the degree of initial entanglement or the purity of initial quantum state, and also their relationship with quantum discord. The results show that the decrease of the purity of an initial quantum state can induce the attenuation of concurrence or quantum discord, but the attenuation of quantum discord is obviously slower than the concurrence's, correspondingly the survival time of quantum discord is longer. Further investigation reveals that the robustness of quantum discord and concurrence relies on the entanglement degree of the initial quantum state. The higher the degree of entanglement, the more robust the quantum discord is than concurrence. And the reverse is equally true. Birth and death happen to quantum discord periodically and a newborn quantum discord comes into being under a certain condition, so does the concurrence. © 2012 Chinese Physical Society and IOP Publishing Ltd.

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