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Jin Wang - One of the best experts on this subject based on the ideXlab platform.

  • steady state entanglement and coherence of two coupled qubits in equilibrium and Nonequilibrium environments
    Physical Review A, 2019
    Co-Authors: Zhihai Wang, Jin Wang
    Abstract:

    We analytically and numerically investigate the steady-state entanglement and coherence of two coupled qubits, each interacting with a local boson or fermion reservoir, based on the Bloch-Redfield master equation beyond the secular approximation. We find that there is nonvanishing steady-state coherence in the Nonequilibrium scenario, which grows monotonically with the Nonequilibrium Condition quantified by the temperature difference or chemical potential difference of the two baths. The steady-state entanglement, in general, is a nonmonotonic function of the Nonequilibrium Condition as well as the bath parameters in the equilibrium setting. We also discover that weak interqubit coupling and high base temperature or chemical potential of the baths can strongly suppress the steady-state entanglement and coherence, regardless of the strength of the Nonequilibrium Condition. On the other hand, the energy detuning of the two qubits, when used in a compensatory way with the Nonequilibrium Condition, can lead to significant enhancement of the steady-state entanglement in some parameter regimes. In addition, the qubits typically have a stronger steady-state entanglement when coupled to fermion baths exchanging particles with the system than boson baths exchanging energy with the system, under similar Conditions. We also identify a close connection between the energy current flowing through the system and the steady-state coherence. Preliminary investigations suggest that these results are insensitive to the form of the reservoir spectral densities in the Markovian regime. Feasible experimental realization of measuring the steady-state entanglement and coherence is discussed for the coupled qubit system in Nonequilibrium environments. Our findings offer some general guidelines for optimizing the steady-state entanglement and coherence in the coupled qubit system and may find potential applications in quantum information technology.

  • coherence enhanced quantum metrology in a Nonequilibrium optical molecule
    New Journal of Physics, 2018
    Co-Authors: Zhihai Wang, Guodong Cui, Jin Wang
    Abstract:

    We explore the quantum metrology in an optical molecular system coupled to two environments with different temperatures, using a quantum master equation beyond secular approximation. We discover that the steady-state coherence originating from and sustained by the Nonequilibrium Condition can enhance quantum metrology. We also study the quantitative measures of the Nonequilibrium Condition in terms of the curl flux, heat current and entropy production at the steady state. They are found to grow with temperature difference. However, an apparent paradox arises considering the contrary behaviors of the steady-state coherence and the Nonequilibrium measures in relation to the inter-cavity coupling strength. This paradox is resolved by decomposing the heat current into a population part and a coherence part. Only the latter, the coherence part of the heat current, is tightly connected to the steady-state coherence and behaves similarly with respect to the inter-cavity coupling strength. Interestingly, the coherence part of the heat current flows from the low-temperature reservoir to the high-temperature reservoir, opposite to the direction of the population heat current. Our work offers a viable way to enhance quantum metrology for open quantum systems through steady-state coherence sustained by the Nonequilibrium Condition, which can be controlled and manipulated to maximize its utility. The potential applications go beyond quantum metrology and extend to areas such as device designing, quantum computation and quantum technology in general.

Zhihai Wang - One of the best experts on this subject based on the ideXlab platform.

  • steady state entanglement and coherence of two coupled qubits in equilibrium and Nonequilibrium environments
    Physical Review A, 2019
    Co-Authors: Zhihai Wang, Jin Wang
    Abstract:

    We analytically and numerically investigate the steady-state entanglement and coherence of two coupled qubits, each interacting with a local boson or fermion reservoir, based on the Bloch-Redfield master equation beyond the secular approximation. We find that there is nonvanishing steady-state coherence in the Nonequilibrium scenario, which grows monotonically with the Nonequilibrium Condition quantified by the temperature difference or chemical potential difference of the two baths. The steady-state entanglement, in general, is a nonmonotonic function of the Nonequilibrium Condition as well as the bath parameters in the equilibrium setting. We also discover that weak interqubit coupling and high base temperature or chemical potential of the baths can strongly suppress the steady-state entanglement and coherence, regardless of the strength of the Nonequilibrium Condition. On the other hand, the energy detuning of the two qubits, when used in a compensatory way with the Nonequilibrium Condition, can lead to significant enhancement of the steady-state entanglement in some parameter regimes. In addition, the qubits typically have a stronger steady-state entanglement when coupled to fermion baths exchanging particles with the system than boson baths exchanging energy with the system, under similar Conditions. We also identify a close connection between the energy current flowing through the system and the steady-state coherence. Preliminary investigations suggest that these results are insensitive to the form of the reservoir spectral densities in the Markovian regime. Feasible experimental realization of measuring the steady-state entanglement and coherence is discussed for the coupled qubit system in Nonequilibrium environments. Our findings offer some general guidelines for optimizing the steady-state entanglement and coherence in the coupled qubit system and may find potential applications in quantum information technology.

  • coherence enhanced quantum metrology in a Nonequilibrium optical molecule
    New Journal of Physics, 2018
    Co-Authors: Zhihai Wang, Guodong Cui, Jin Wang
    Abstract:

    We explore the quantum metrology in an optical molecular system coupled to two environments with different temperatures, using a quantum master equation beyond secular approximation. We discover that the steady-state coherence originating from and sustained by the Nonequilibrium Condition can enhance quantum metrology. We also study the quantitative measures of the Nonequilibrium Condition in terms of the curl flux, heat current and entropy production at the steady state. They are found to grow with temperature difference. However, an apparent paradox arises considering the contrary behaviors of the steady-state coherence and the Nonequilibrium measures in relation to the inter-cavity coupling strength. This paradox is resolved by decomposing the heat current into a population part and a coherence part. Only the latter, the coherence part of the heat current, is tightly connected to the steady-state coherence and behaves similarly with respect to the inter-cavity coupling strength. Interestingly, the coherence part of the heat current flows from the low-temperature reservoir to the high-temperature reservoir, opposite to the direction of the population heat current. Our work offers a viable way to enhance quantum metrology for open quantum systems through steady-state coherence sustained by the Nonequilibrium Condition, which can be controlled and manipulated to maximize its utility. The potential applications go beyond quantum metrology and extend to areas such as device designing, quantum computation and quantum technology in general.

Wang Jin - One of the best experts on this subject based on the ideXlab platform.

  • Influence of equilibrium and Nonequilibrium environments on macroscopic realism through the Leggett-Garg inequalities
    'American Physical Society (APS)', 2020
    Co-Authors: Zhang Kun, Wu Wei, Wang Jin
    Abstract:

    We study the macroscopic realism (macrorealism) through the two- and three-time Leggett-Garg inequalities (LGIs) in a two interacting qubits system. The two qubits are coupled either with two bosonic (thermal or photonic) baths or fermionic (electronic) baths. We study both how the equilibrium and Nonequilibrium environments influence the LGIs. One way to characterize the Nonequilibrium Condition is by the temperature difference (for the bosonic bath) or the chemical potential difference (for the fermionic bath). We also study the heat or particle current and the entropy production rate generated by the Nonequilibrium environments. Analytical forms of LGIs and the maximal value of LGIs based on the quantum master equation beyond the secular approximation are derived. The LGI functions and the corresponding maximal value have separated contributions, the part describing the coherent evolution and the part describing the coupling between the system and environments. The environment-coupling part can be from the equilibrium environment or the Nonequilibrium environment. The Nonequilibrium dynamics is quantified by the Bloch-Redfield equation which is beyond the Lindblad form. We found that the Nonequilibriumness quantified by the temperature difference or the chemical potential difference can lead to the LGIs violations or the increase of the maximal value of LGIs, restoring the quantum nature from certain equilibrium cases where LGIs are preserved. The corresponding Nonequilibrium thermodynamic cost is quantified by the nonzero entropy production rate. Our finding of the Nonequilibrium promoted LGIs violations suggests a new strategy for the design of quantum information processing and quantum computational devices to maintain the quantum nature and quantum correlations for long.Comment: Published version, 25 pages, 15 figure

  • Steady-state entanglement and coherence of the coupled qubit system in equilibrium and Nonequilibrium environments
    'American Physical Society (APS)', 2019
    Co-Authors: Wang Zhihai, Wu Wei, Wang Jin
    Abstract:

    We investigate analytically and numerically the steady-state entanglement and coherence of two coupled qubits each interacting with a local boson or fermion reservoir, based on the Bloch-Redfield master equation beyond the secular approximation. We find that there is non-vanishing steady-state coherence in the Nonequilibrium scenario, which grows monotonically with the Nonequilibrium Condition quantified by the temperature difference or chemical potential difference of the two baths. The steady-state entanglement in general is a non-monotonic function of the Nonequilibrium Condition as well as the bath parameters in the equilibrium setting. We also find that weak inter-qubit coupling and high base temperature or chemical potential of the baths can strongly suppress the steady-state entanglement and coherence, regardless of the strength of the Nonequilibrium Condition. On the other hand, the energy detuning of the two qubits, when used in a compensatory way with the Nonequilibrium Condition, can lead to significant enhancement of the steady-state entanglement in some parameter regimes. In addition, the qubits typically have a stronger steady-state entanglement when coupled to fermion baths exchanging particle with the system than boson baths exchanging energy with the system under similar Conditions. We also discussed the possible experimental realization of measuring the steady state entanglement and coherence for coupled qubits systems in Nonequilibrium environments. These results offer some general guidelines for optimizing the steady-state entanglement and coherence in the coupled qubit system and may find potential applications in quantum information technology.Comment: 21 pages, 9 figures, comments are welcomed, Accepted by Phys. Rev.

  • Coherence enhanced quantum metrology in a Nonequilibrium optical molecule
    'IOP Publishing', 2018
    Co-Authors: Wang Zhihai, Cui, Wei Wu. Guodong, Wang Jin
    Abstract:

    We explore the quantum metrology in an optical molecular system coupled to two environments with different temperatures, using a quantum master equation beyond secular approximation. We discover that the steady-state coherence originating from and sustained by the Nonequilibrium Condition can enhance quantum metrology. We also study the quantitative measures of the Nonequilibrium Condition in terms of the curl flux, heat current and entropy production at the steady state. They are found to grow with temperature difference. However, an apparent paradox arises considering the contrary behaviors of the steady-state coherence and the Nonequilibrium measures in relation to the inter-cavity coupling strength. This paradox is resolved by decomposing the heat current into a population part and a coherence part. Only the latter, coherence heat current, is tightly connected to the steady-state coherence and behaves similarly with respect to the inter-cavity coupling strength. Interestingly, the coherence heat current flows from the low-temperature reservoir to the high-temperature reservoir, opposite to the direction of the population heat current. Our work offers a viable way to enhance quantum metrology for open quantum systems through steady-state coherence sustained by the Nonequilibrium Condition, which can be controlled and manipulated to maximize its utility. The potential applications go beyond quantum metrology and extend to areas such as device designing, quantum computation and quantum technology in general.Comment: The errors are corrected, analytical results are added, acceptec by New J. Phy

Jun Yonggun - One of the best experts on this subject based on the ideXlab platform.

  • Optical tweezers as a mathematically driven spatio-temporal potential generator
    'The Optical Society', 2018
    Co-Authors: Albay, John A. C., Paneru Govind, Pak, Hyuk Kyu, Jun Yonggun
    Abstract:

    The ability to create and manipulate spatio-temporal potentials is essential in the diverse fields of science and technology. Here, we introduce an optical feedback trap system based on high precision position detection and ultrafast feedback control of a Brownian particle in the optical tweezers to generate spatio-temporal virtual potentials of the desired shape in a controlled manner. As an application, we study the Nonequilibrium fluctuation dynamics of the particle in a time-varying virtual harmonic potential and validate the Crooks fluctuation theorem in the highly Nonequilibrium Condition

  • Optical tweezers as a mathematically driven spatio-temporal potential generator
    'The Optical Society', 2018
    Co-Authors: Albay, John A. C., Paneru Govind, Pak, Hyuk Kyu, Jun Yonggun
    Abstract:

    The ability to create and manipulate the spatio-temporal potentials is essential in the diverse fields of science and technology. Here, we introduce an optical feedback trap system based on a high precision position detection and an ultrafast feedback control of a Brownian particle in the optical tweezers to generate spatio-temporal virtual potentials of the desired shape in a controlled manner. As an application, we study Nonequilibrium fluctuation dynamics of the particle in a time-varying virtual harmonic potential and validate the Crooks fluctuation theorem in highly Nonequilibrium Condition

Guodong Cui - One of the best experts on this subject based on the ideXlab platform.

  • coherence enhanced quantum metrology in a Nonequilibrium optical molecule
    New Journal of Physics, 2018
    Co-Authors: Zhihai Wang, Guodong Cui, Jin Wang
    Abstract:

    We explore the quantum metrology in an optical molecular system coupled to two environments with different temperatures, using a quantum master equation beyond secular approximation. We discover that the steady-state coherence originating from and sustained by the Nonequilibrium Condition can enhance quantum metrology. We also study the quantitative measures of the Nonequilibrium Condition in terms of the curl flux, heat current and entropy production at the steady state. They are found to grow with temperature difference. However, an apparent paradox arises considering the contrary behaviors of the steady-state coherence and the Nonequilibrium measures in relation to the inter-cavity coupling strength. This paradox is resolved by decomposing the heat current into a population part and a coherence part. Only the latter, the coherence part of the heat current, is tightly connected to the steady-state coherence and behaves similarly with respect to the inter-cavity coupling strength. Interestingly, the coherence part of the heat current flows from the low-temperature reservoir to the high-temperature reservoir, opposite to the direction of the population heat current. Our work offers a viable way to enhance quantum metrology for open quantum systems through steady-state coherence sustained by the Nonequilibrium Condition, which can be controlled and manipulated to maximize its utility. The potential applications go beyond quantum metrology and extend to areas such as device designing, quantum computation and quantum technology in general.