Quantum Fisher information is related to the problem of parameter estimation. Recently, a criterion has been proposed for entanglement in multipartite systems based on quantum Fisher information. This paper studies th...Quantum Fisher information is related to the problem of parameter estimation. Recently, a criterion has been proposed for entanglement in multipartite systems based on quantum Fisher information. This paper studies the behaviours of quantum Fisher information in the quantum kicked top model, whose classical correspondence can be chaotic. It finds that, first, detected by quantum Fisher information, the quantum kicked top is entangled whether the system is in chaotic or in regular case. Secondly, the quantum Fisher information is larger in chaotic case than that in regular case, which means, the system is more sensitive in the chaotic case.展开更多
Quantum teleportation is designed to send an unknown quantum state between two parties.In the perspective of remote quantum metrology,one may be interested in teleporting the information that is encoded by physical pa...Quantum teleportation is designed to send an unknown quantum state between two parties.In the perspective of remote quantum metrology,one may be interested in teleporting the information that is encoded by physical parameters synthesized by quantum Fisher information(QFI).However,the teleported QFI is often destroyed by the unavoidable interaction between the system and the environment.Here,we propose two schemes to improve the teleportation of QFI in the non-Markovian environment.One is to control the quantum system through the operations of weak measurement(WM)and corresponding quantum measurement reversal(QMR).The other is to modify the quantum system based on the monitoring result of the environment(i.e.,environment-assisted measurement,EAM).It is found that,in the non-Markovian environment,these two schemes can improve the teleportation of QFI.By selecting the appropriate strengths of WM and QMR,the environment noise can be completely eliminated and the initial QFI is perfectly teleported.A comprehensive comparison shows that the second scheme not only has a higher probability of success than the first one,but also has a significant improvement of the teleported QFI.展开更多
By using the non-Markovian master equation, we investigate the effect of the cavity and the environment on the quantum Fisher information(QFI) of an atom qubit system in a dissipation cavity. We obtain the formulae ...By using the non-Markovian master equation, we investigate the effect of the cavity and the environment on the quantum Fisher information(QFI) of an atom qubit system in a dissipation cavity. We obtain the formulae of QFI for two different initial states and analyze the effect of the atom–cavity coupling and the cavity–reservoir coupling on the QFI.The results show that the dynamic behavior of the QFI is obviously dependent on the initial atomic states, the atom–cavity coupling, and the cavity–reservoir coupling. The stronger the atom–cavity coupling, the quicker the QFI oscillates, and the slower the QFI decreases. In particular, the QFI will tend to be a stable value rather than zero if the atom–cavity coupling is large enough. On the other hand, the smaller the cavity–reservoir coupling, the stronger the non-Markovian effect, and the slower the QFI decays. In other words, choosing the best parameter can improve the accuracy of the parameter estimation.In addition, the physical explanation of the dynamic behavior of the QFI is given by means of the QFI flow.展开更多
We consider the optimal parameter estimation for a two-level system coupled to multiple bosonic reservoirs. By using quantum Fisher information (QFI), we investigate the effect of the Markovian reservoirs' number N...We consider the optimal parameter estimation for a two-level system coupled to multiple bosonic reservoirs. By using quantum Fisher information (QFI), we investigate the effect of the Markovian reservoirs' number N on QFI in both weak and strong coupling regimes for a two-level system surrounded by N zero-temperature reservoirs of field modes initially in the vacua. The results show that the dynamics of QFI non-monotonically decays to zero with revival oscillations at some time in the weak coupling regime depending on the reservoirs' parameters. Furthermore, we also present the relations between the QFI flow, the flows of energy and information, and the sign of the decay rate to gain insight into the physical processes characterizing the dynamics.展开更多
We investigate the dependence of the average parameter estimation precision (APEP), which is defined by the quantum Fisher information, on the polar angle of the initial coherent spin state |θ0,φ0〉 in a one-axis...We investigate the dependence of the average parameter estimation precision (APEP), which is defined by the quantum Fisher information, on the polar angle of the initial coherent spin state |θ0,φ0〉 in a one-axis twisting model. Jin et al. [New J. Phys. 11 (2009) 073049] found that the spin squeezing sensitively depends on the polar angle θ0 of the initial coherent spin state. We show explicitly that the APEP is robust to the initial polar angle θ0 in the vicinity of π/2 and a near- Heisenberg limit 2IN in quantum single-parameter estimation may still be achieved for states created with the nonlinear evolution of the nonideal coherent spin states θ0- π/2. Based on this model, we also consider the effects of the collective dephasing on spin squeezing and the APEE展开更多
We analytically investigate the dynamics of quantum Fisher information of two qubits in independent environments for both uncorrelated and entangled input states.Especially,we observe that,in the non-Markovian regime ...We analytically investigate the dynamics of quantum Fisher information of two qubits in independent environments for both uncorrelated and entangled input states.Especially,we observe that,in the non-Markovian regime and resonant case,quantum Fisher information of uncorrelated input state vanishes only at discrete time point whereas that of entangled input state can disappear during finite time interval.It shows that quantum Fisher information,which determines the parameter estimation precision,is strongly affected by the environment memory effects,and the advantage of entanglement-enhance metrology no longer exists even for a very short time.We also note that quantum Fisher information for two kinds of input states can be preserved under appropriate qubit-reservoir detuning.展开更多
Nonclassicality is an essential but still open question in quantum mechanics. Here, utilizing the maximum value of quantum Fisher information, we suggest a new version of the nonclassical criterion for SU(2) generator...Nonclassicality is an essential but still open question in quantum mechanics. Here, utilizing the maximum value of quantum Fisher information, we suggest a new version of the nonclassical criterion for SU(2) generator realized by two bosonic modes. As an application of the criterion, the system of two coupled nonlinear nanomechanical resonators is considered. And the nonclassicality of the phonon state in the dynamical evolution is explored. The system has a dynamical phase transition from the tunnelling phase to the self-trapping phase by tuning the coupling strength. It is found that for the tunnelling phase, the phonon state is nonclassical in the full time evolution. And for the self-trapping phase, the evolved phonon state is still nonclassical in the full time with a relatively large coupling strength, while it is nonclassical i n the most of time (but not all) with a small coupling strength. Quantum coherence has distinct different behaviors in the two phases.展开更多
The Berezinskii-Kosterlitz-Thouless phase transition of spin-1/2 XXZ chain is reinvestigated by the quantum Fisher information.Quantum Fisher informations of the whole N sites and the partial N/3 sites display remarka...The Berezinskii-Kosterlitz-Thouless phase transition of spin-1/2 XXZ chain is reinvestigated by the quantum Fisher information.Quantum Fisher informations of the whole N sites and the partial N/3 sites display remarkably similar behaviors near the critical point.The critical exponent of quantum Fisher information is obtained as β=0.47,which is consistent with the results obtained by the concurrence and quantum discord.展开更多
We study the quantum Fisher information(QFI) dynamics of the phase parameter in the enlarged cavityreservoir systems at zero temperature under two situations of large N limit and non-Markovian environment,respectively...We study the quantum Fisher information(QFI) dynamics of the phase parameter in the enlarged cavityreservoir systems at zero temperature under two situations of large N limit and non-Markovian environment,respectively.We find an important relation that the total quantities of QFI of the cavity and reservoir are equal to unit during the dynamical evolution.The lost QFI of the cavity transfers to its corresponding reservoir with the same quantities simultaneously.Moreover,we also find that the detuning parameter and non-Markovian effect are two significant factors to affect the preservation of QFI.展开更多
In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Ke...In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Kerr medium (non-linear) and the Stark effect. The wave function of the complete system interacting with a coherent and the thermal field is calculated numerically affected by ID, Kerr (non-linear) and Stark effects. It has been seen that the Stark, Kerr, ID and the thermal environment have a significant effect during the time evolution of the quantum system. Quantum Fisher information (QFI) and QE decrease as the value of the ID parameter is increased in the thermal field without the atomic movement. It is seen that QFI and von Neumann entropy (VNE) show an opposite and periodic response in the presence of atomic motion. The non-linear Kerr medium has a more prominent and significant effect on the QE as the value of the Kerr parameter is decreased. At smaller values of the non-linear Kerr parameter, the VNE increases, however, QFI decreases, so QFI and VNE have a monotonic connection with one another. As the value of the Kerr parameter is increased, the effect of non-linear Kerr doesn’t stay critical on both QFI and QE. However, a periodic response of QE is seen because of the atomic movement which becomes modest under natural impacts. Moreover, it has been seen that QFI and QE rot soon at the smaller values of the Stark parameter. However, as the value of the Stark parameter is increased, the QFI and QE show periodic response even when the atomic movement is absent.展开更多
We study the local quantum Fisher information(LQFI)in the mixed-spin Heisenberg XXZ chain.Both the maximal and minimal LQFI are studied and the former is essential to determine the accuracy of the quantum parameter es...We study the local quantum Fisher information(LQFI)in the mixed-spin Heisenberg XXZ chain.Both the maximal and minimal LQFI are studied and the former is essential to determine the accuracy of the quantum parameter estimation,the latter can be well used to characterize the discord-type quantum correlations.We investigate the effects of the temperature and the anisotropy parameter on the maximal LQFI and thus on the accuracy of the parameter estimation.Then we make use of the minimal LQFI to study the discord-type correlations of different site pairs.Different dimensions of the subsystems cause different values of the minimal LQFI which reflects the asymmetry of the discord-type correlation.In addition,the site pairs at different positions of the spin chains have different minimal LQFI,which reveals the influence of the surrounding spins on the bipartite quantum correlation.Our results show that the LQFI obtained through a simple calculation process provides a convenient way to investigate the discord-type correlation in high-dimensional systems.展开更多
The dynamics of the quantum Fisher information(QFI) of phase parameter estimation in a non-Markovian dissipative qubit system is investigated within the structure of single and double Lorentzian spectra. We use the ti...The dynamics of the quantum Fisher information(QFI) of phase parameter estimation in a non-Markovian dissipative qubit system is investigated within the structure of single and double Lorentzian spectra. We use the time-convolutionless method with fourth-order perturbation expansion to obtain the general forms of QFI for the qubit system in terms of a non-Markovian master equation. We find that the phase parameter estimation can be enhanced in our model within both single and double Lorentzian spectra. What is more, the detuning and spectral width are two significant factors affecting the enhancement of parameter-estimation precision.展开更多
The enhancement of the precision of phase estimation in quantum metrology is investigated by employing weak measurement (WM) and quantum measurement reversal (QMR). We derive the exact expressions of the optimal q...The enhancement of the precision of phase estimation in quantum metrology is investigated by employing weak measurement (WM) and quantum measurement reversal (QMR). We derive the exact expressions of the optimal quantum Fisher information (QFI) and success probability of phase estimation for an exactly solving model consisting of a qubit interacting with a structured reservoir. We show that the QFI can be obviously enhanced by means of the WM and QMR in different regimes. In addition, we also show that the magnitude of the decoherence involved in the WM and QMR can be a general complex number, which extends the applicable scope of the WM and QMR approach.展开更多
We propose a scheme of quantum screening to enhance the parameter-estimation precision in open quantum systems by means of the dynamics of quantum Fisher information. The principle of quantum screening is based on an ...We propose a scheme of quantum screening to enhance the parameter-estimation precision in open quantum systems by means of the dynamics of quantum Fisher information. The principle of quantum screening is based on an auxiliary system to inhibit the decoherence processes and erase the excited state to the ground state. By comparing the case without quantum screening, the results show that the dynamics of quantum Fisher information with quantum screening has a larger value during the evolution processes.展开更多
We investigate the advantage of coherent superposition of two different coded channels in quantum metrology.In a continuous variable system,we show that the Heisenberg limit 1/N can be beaten by the coherent superposi...We investigate the advantage of coherent superposition of two different coded channels in quantum metrology.In a continuous variable system,we show that the Heisenberg limit 1/N can be beaten by the coherent superposition without the help of indefinite causal order.And in parameter estimation,we demonstrate that the strategy with the coherent superposition can perform better than the strategy with quantum switch which can generate indefinite causal order.We analytically obtain the general form of estimation precision in terms of the quantum Fisher information and further prove that the nonlinear Hamiltonian can improve the estimation precision and make the measurement uncertainty scale as 1/N^(m) for m≥2.Our results can help to construct a high-precision measurement equipment,which can be applied to the detection of coupling strength and the test of time dilation and the modification of the canonical commutation relation.展开更多
Adopting the Milburn decoherence model, we investigate the performance of quantum Fisher information of the twoqutrit isotropic Heisenberg XY chain under decoherence. We find that the quantum Fisher information with r...Adopting the Milburn decoherence model, we investigate the performance of quantum Fisher information of the twoqutrit isotropic Heisenberg XY chain under decoherence. We find that the quantum Fisher information with respect to the decoherence rate and the magnetic field decreases exponentially in the long-time limit, which significantly reduces the precision of optimal quantum estimation. We also show that with the increase of the decoherence rate or the magnetic field,the QFIs go down considerably. Furthermore, we find that the precision of optimal quantum estimation can be enhanced by the entanglement in the input state.展开更多
In quantum information technologies,quantum weak measurement is beneficial for protecting coherence of systems.In order to further improve the protection effect of quantum weak measurement on coherence,we propose an o...In quantum information technologies,quantum weak measurement is beneficial for protecting coherence of systems.In order to further improve the protection effect of quantum weak measurement on coherence,we propose an optimization scheme of quantum Fisher information(QFI)protection in an open quantum system by combing no-knowledge quantum feedback control with quantum weak measurement.On the basis of solving the dynamic equations of a stochastic two-level quantum system under feedback control,we compare the effects of different feedback Hamiltonians on QFI and find that via no-knowledge quantum feedback,the observation operatorσx(orσx andσz)can protect QFI for a long time.Namely,no-knowledge quantum feedback can improve the estimation precision of feedback coefficient as well as that of detection coefficient.展开更多
We investigate the quantum Fisher information(QFI) of a qubit-qutrit system in the background of Garfinkle–Horowitz–Strominger dilation black hole. After deriving the analytical expression of the QFI, we examine its...We investigate the quantum Fisher information(QFI) of a qubit-qutrit system in the background of Garfinkle–Horowitz–Strominger dilation black hole. After deriving the analytical expression of the QFI, we examine its dynamics with respect to the dilation parameter D and the state parameter γ of the system. Our results show that the QFI for the estimation of γ is a fixed value,which is independent of the parameters D and γ. And the QFI for the estimation of D varies with the parameters D and γ. Additionally, we propose an effective strategy to steer the QFI by introducing weak measurement reversal. We find that the QFI can be remarkably enhanced by adjusting the appropriate reversing measurement strengths. Our findings might provide some useful insights for the study on parameter estimation of hybrid systems in the framework of relativity theory.展开更多
基金Project supported by National Natural Science Foundation of China (Grant Nos. 11025527,10874151,and 10935010)
文摘Quantum Fisher information is related to the problem of parameter estimation. Recently, a criterion has been proposed for entanglement in multipartite systems based on quantum Fisher information. This paper studies the behaviours of quantum Fisher information in the quantum kicked top model, whose classical correspondence can be chaotic. It finds that, first, detected by quantum Fisher information, the quantum kicked top is entangled whether the system is in chaotic or in regular case. Secondly, the quantum Fisher information is larger in chaotic case than that in regular case, which means, the system is more sensitive in the chaotic case.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61765007 and 12265004)Jiangxi Provincial Natural Science Foundation,China (Grant No.20212ACB211004)Innovation Foundation of Jiangxi University of Science and Technology (Grant No.XY2021-S088)。
文摘Quantum teleportation is designed to send an unknown quantum state between two parties.In the perspective of remote quantum metrology,one may be interested in teleporting the information that is encoded by physical parameters synthesized by quantum Fisher information(QFI).However,the teleported QFI is often destroyed by the unavoidable interaction between the system and the environment.Here,we propose two schemes to improve the teleportation of QFI in the non-Markovian environment.One is to control the quantum system through the operations of weak measurement(WM)and corresponding quantum measurement reversal(QMR).The other is to modify the quantum system based on the monitoring result of the environment(i.e.,environment-assisted measurement,EAM).It is found that,in the non-Markovian environment,these two schemes can improve the teleportation of QFI.By selecting the appropriate strengths of WM and QMR,the environment noise can be completely eliminated and the initial QFI is perfectly teleported.A comprehensive comparison shows that the second scheme not only has a higher probability of success than the first one,but also has a significant improvement of the teleported QFI.
基金Project supported by the Scientific Research Project of Hunan Provincial Education Department,China(Grant No.16C0949)Hunan Provincial Innovation Foundation for Postgraduate,China(Grant No.CX2017B177)+1 种基金the National Natural Science Foundation of China(Grant No.11374096)the Doctoral Science Foundation of Hunan Normal University,China
文摘By using the non-Markovian master equation, we investigate the effect of the cavity and the environment on the quantum Fisher information(QFI) of an atom qubit system in a dissipation cavity. We obtain the formulae of QFI for two different initial states and analyze the effect of the atom–cavity coupling and the cavity–reservoir coupling on the QFI.The results show that the dynamic behavior of the QFI is obviously dependent on the initial atomic states, the atom–cavity coupling, and the cavity–reservoir coupling. The stronger the atom–cavity coupling, the quicker the QFI oscillates, and the slower the QFI decreases. In particular, the QFI will tend to be a stable value rather than zero if the atom–cavity coupling is large enough. On the other hand, the smaller the cavity–reservoir coupling, the stronger the non-Markovian effect, and the slower the QFI decays. In other words, choosing the best parameter can improve the accuracy of the parameter estimation.In addition, the physical explanation of the dynamic behavior of the QFI is given by means of the QFI flow.
基金supported by the Hunan Provincial Innovation Foundation for Postgraduate,China(Grant No.CX2014B194)the Scientific Research Foundation of Hunan Provincial Education Department,China(Grant No.13C039)
文摘We consider the optimal parameter estimation for a two-level system coupled to multiple bosonic reservoirs. By using quantum Fisher information (QFI), we investigate the effect of the Markovian reservoirs' number N on QFI in both weak and strong coupling regimes for a two-level system surrounded by N zero-temperature reservoirs of field modes initially in the vacua. The results show that the dynamics of QFI non-monotonically decays to zero with revival oscillations at some time in the weak coupling regime depending on the reservoirs' parameters. Furthermore, we also present the relations between the QFI flow, the flows of energy and information, and the sign of the decay rate to gain insight into the physical processes characterizing the dynamics.
基金supported by the National Basic Research Program of China(Grant No.2012CB921602)the National Natural Science Foundation of China(Grant Nos.11025527 and 10935010)
文摘We investigate the dependence of the average parameter estimation precision (APEP), which is defined by the quantum Fisher information, on the polar angle of the initial coherent spin state |θ0,φ0〉 in a one-axis twisting model. Jin et al. [New J. Phys. 11 (2009) 073049] found that the spin squeezing sensitively depends on the polar angle θ0 of the initial coherent spin state. We show explicitly that the APEP is robust to the initial polar angle θ0 in the vicinity of π/2 and a near- Heisenberg limit 2IN in quantum single-parameter estimation may still be achieved for states created with the nonlinear evolution of the nonideal coherent spin states θ0- π/2. Based on this model, we also consider the effects of the collective dephasing on spin squeezing and the APEE
基金Supported by the National Natural Science Foundation of China under Grant Nos.11275064,11075050the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20124306110003+1 种基金the Scientific Research Foundation of the Education Department of Hunan Province under Grant No.13C039the Construct Program of the National Key Discipline
文摘We analytically investigate the dynamics of quantum Fisher information of two qubits in independent environments for both uncorrelated and entangled input states.Especially,we observe that,in the non-Markovian regime and resonant case,quantum Fisher information of uncorrelated input state vanishes only at discrete time point whereas that of entangled input state can disappear during finite time interval.It shows that quantum Fisher information,which determines the parameter estimation precision,is strongly affected by the environment memory effects,and the advantage of entanglement-enhance metrology no longer exists even for a very short time.We also note that quantum Fisher information for two kinds of input states can be preserved under appropriate qubit-reservoir detuning.
基金Supported by the National Natural Science Foundation of China under Grant No.11365006the Natural Science Foundation of Guizhou Province under Grant No.QKHLHZ[2015]7767
文摘Nonclassicality is an essential but still open question in quantum mechanics. Here, utilizing the maximum value of quantum Fisher information, we suggest a new version of the nonclassical criterion for SU(2) generator realized by two bosonic modes. As an application of the criterion, the system of two coupled nonlinear nanomechanical resonators is considered. And the nonclassicality of the phonon state in the dynamical evolution is explored. The system has a dynamical phase transition from the tunnelling phase to the self-trapping phase by tuning the coupling strength. It is found that for the tunnelling phase, the phonon state is nonclassical in the full time evolution. And for the self-trapping phase, the evolved phonon state is still nonclassical in the full time with a relatively large coupling strength, while it is nonclassical i n the most of time (but not all) with a small coupling strength. Quantum coherence has distinct different behaviors in the two phases.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11065005 and 11365006the Innovation Team Foundation of the Education Department of Guizhou Province under Grant No.[2014]35
文摘The Berezinskii-Kosterlitz-Thouless phase transition of spin-1/2 XXZ chain is reinvestigated by the quantum Fisher information.Quantum Fisher informations of the whole N sites and the partial N/3 sites display remarkably similar behaviors near the critical point.The critical exponent of quantum Fisher information is obtained as β=0.47,which is consistent with the results obtained by the concurrence and quantum discord.
基金Supported by the National Natural Science Foundation of China under Grant No.11374096the Natural Science Foundation of Guangdong Province under Grant No.2015A030310354the Projection of Enhancing School with Innovation of Guangdong Ocean University under Grant Nos.GDOU2014050251 and GDOU2014050252
文摘We study the quantum Fisher information(QFI) dynamics of the phase parameter in the enlarged cavityreservoir systems at zero temperature under two situations of large N limit and non-Markovian environment,respectively.We find an important relation that the total quantities of QFI of the cavity and reservoir are equal to unit during the dynamical evolution.The lost QFI of the cavity transfers to its corresponding reservoir with the same quantities simultaneously.Moreover,we also find that the detuning parameter and non-Markovian effect are two significant factors to affect the preservation of QFI.
文摘In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Kerr medium (non-linear) and the Stark effect. The wave function of the complete system interacting with a coherent and the thermal field is calculated numerically affected by ID, Kerr (non-linear) and Stark effects. It has been seen that the Stark, Kerr, ID and the thermal environment have a significant effect during the time evolution of the quantum system. Quantum Fisher information (QFI) and QE decrease as the value of the ID parameter is increased in the thermal field without the atomic movement. It is seen that QFI and von Neumann entropy (VNE) show an opposite and periodic response in the presence of atomic motion. The non-linear Kerr medium has a more prominent and significant effect on the QE as the value of the Kerr parameter is decreased. At smaller values of the non-linear Kerr parameter, the VNE increases, however, QFI decreases, so QFI and VNE have a monotonic connection with one another. As the value of the Kerr parameter is increased, the effect of non-linear Kerr doesn’t stay critical on both QFI and QE. However, a periodic response of QE is seen because of the atomic movement which becomes modest under natural impacts. Moreover, it has been seen that QFI and QE rot soon at the smaller values of the Stark parameter. However, as the value of the Stark parameter is increased, the QFI and QE show periodic response even when the atomic movement is absent.
基金supported by the National Natural Science Foundation of China(NSFC)under Grant No.12175052the Postdoctoral Science Foundation of China(No.2022M722794).
文摘We study the local quantum Fisher information(LQFI)in the mixed-spin Heisenberg XXZ chain.Both the maximal and minimal LQFI are studied and the former is essential to determine the accuracy of the quantum parameter estimation,the latter can be well used to characterize the discord-type quantum correlations.We investigate the effects of the temperature and the anisotropy parameter on the maximal LQFI and thus on the accuracy of the parameter estimation.Then we make use of the minimal LQFI to study the discord-type correlations of different site pairs.Different dimensions of the subsystems cause different values of the minimal LQFI which reflects the asymmetry of the discord-type correlation.In addition,the site pairs at different positions of the spin chains have different minimal LQFI,which reveals the influence of the surrounding spins on the bipartite quantum correlation.Our results show that the LQFI obtained through a simple calculation process provides a convenient way to investigate the discord-type correlation in high-dimensional systems.
基金Projects supported by the Natural Science Foundation of Guangdong Province,China(Grant No.2015A030310354)the Science Foundation for Enhancing School with Innovation of Guangdong Ocean University(Grant Nos.GDOU2017052504 and GDOU2015050207)+1 种基金the Foundation of Excellent-YoungBackbone Teacher of Guangdong Ocean University(Grant No.HDYQ2017005)the Fund of University Student Innovation and Entrepreneurship Team of Guangdong Ocean University(Grant No.CCTD201823)
文摘The dynamics of the quantum Fisher information(QFI) of phase parameter estimation in a non-Markovian dissipative qubit system is investigated within the structure of single and double Lorentzian spectra. We use the time-convolutionless method with fourth-order perturbation expansion to obtain the general forms of QFI for the qubit system in terms of a non-Markovian master equation. We find that the phase parameter estimation can be enhanced in our model within both single and double Lorentzian spectra. What is more, the detuning and spectral width are two significant factors affecting the enhancement of parameter-estimation precision.
基金supported by the National Natural Science Foundation of China(Grants No.11247294)the Research Foundation of Education Bureau of Hunan Province,China(Grant No.12C0826)+2 种基金the Doctor Foundation Startup from Hunan University of Arts and Science,China(Grant No.13101039)the Key Laboratory of Photoelectricity Information Integration and Optics Manufacture Technology in Hunan Province,Chinathe Construct Program of the Key Discipline in Hunan University of Arts and Science(Optics),China
文摘The enhancement of the precision of phase estimation in quantum metrology is investigated by employing weak measurement (WM) and quantum measurement reversal (QMR). We derive the exact expressions of the optimal quantum Fisher information (QFI) and success probability of phase estimation for an exactly solving model consisting of a qubit interacting with a structured reservoir. We show that the QFI can be obviously enhanced by means of the WM and QMR in different regimes. In addition, we also show that the magnitude of the decoherence involved in the WM and QMR can be a general complex number, which extends the applicable scope of the WM and QMR approach.
基金Project supported by the National Natural Science Foundation of China(Grant No.11374096)the Natural Science Foundation of Guangdong Province,China(Grants No.2015A030310354)the Project of Enhancing School with Innovation of Guangdong Ocean University(Grants Nos.GDOU2014050251 and GDOU2014050252)
文摘We propose a scheme of quantum screening to enhance the parameter-estimation precision in open quantum systems by means of the dynamics of quantum Fisher information. The principle of quantum screening is based on an auxiliary system to inhibit the decoherence processes and erase the excited state to the ground state. By comparing the case without quantum screening, the results show that the dynamics of quantum Fisher information with quantum screening has a larger value during the evolution processes.
基金Project supported by the National Natural Science Foundation of China(Grant No.62001134)the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant No.2020GXNSFAA159047)the National Key Research and Development Program of China(Grant No.2018YFB1601402-2).
文摘We investigate the advantage of coherent superposition of two different coded channels in quantum metrology.In a continuous variable system,we show that the Heisenberg limit 1/N can be beaten by the coherent superposition without the help of indefinite causal order.And in parameter estimation,we demonstrate that the strategy with the coherent superposition can perform better than the strategy with quantum switch which can generate indefinite causal order.We analytically obtain the general form of estimation precision in terms of the quantum Fisher information and further prove that the nonlinear Hamiltonian can improve the estimation precision and make the measurement uncertainty scale as 1/N^(m) for m≥2.Our results can help to construct a high-precision measurement equipment,which can be applied to the detection of coupling strength and the test of time dilation and the modification of the canonical commutation relation.
基金supported by the National Natural Science Foundation of China(Grant Nos.11365006 and 11565010)Guizhou Province Science and Technology Innovation Talent Team,China(Grant No.(2015)4015)+2 种基金Innovation Team Foundation of the Education Department of Guizhou Province,China(Grant No.[2014]35)the Natural Science Foundation of Guizhou Province,China(Grant No.QKHLHZ[2015]7767)High Level Creative Talents,China(Grant No.(2016)-4008)
文摘Adopting the Milburn decoherence model, we investigate the performance of quantum Fisher information of the twoqutrit isotropic Heisenberg XY chain under decoherence. We find that the quantum Fisher information with respect to the decoherence rate and the magnetic field decreases exponentially in the long-time limit, which significantly reduces the precision of optimal quantum estimation. We also show that with the increase of the decoherence rate or the magnetic field,the QFIs go down considerably. Furthermore, we find that the precision of optimal quantum estimation can be enhanced by the entanglement in the input state.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61663016 and 11264015)。
文摘In quantum information technologies,quantum weak measurement is beneficial for protecting coherence of systems.In order to further improve the protection effect of quantum weak measurement on coherence,we propose an optimization scheme of quantum Fisher information(QFI)protection in an open quantum system by combing no-knowledge quantum feedback control with quantum weak measurement.On the basis of solving the dynamic equations of a stochastic two-level quantum system under feedback control,we compare the effects of different feedback Hamiltonians on QFI and find that via no-knowledge quantum feedback,the observation operatorσx(orσx andσz)can protect QFI for a long time.Namely,no-knowledge quantum feedback can improve the estimation precision of feedback coefficient as well as that of detection coefficient.
基金the National Natural Science Foundation of China under Grant Nos.91950112 and 11174081the National Key Research and Development Program of China under Grant No.2016YFB0501601。
文摘We investigate the quantum Fisher information(QFI) of a qubit-qutrit system in the background of Garfinkle–Horowitz–Strominger dilation black hole. After deriving the analytical expression of the QFI, we examine its dynamics with respect to the dilation parameter D and the state parameter γ of the system. Our results show that the QFI for the estimation of γ is a fixed value,which is independent of the parameters D and γ. And the QFI for the estimation of D varies with the parameters D and γ. Additionally, we propose an effective strategy to steer the QFI by introducing weak measurement reversal. We find that the QFI can be remarkably enhanced by adjusting the appropriate reversing measurement strengths. Our findings might provide some useful insights for the study on parameter estimation of hybrid systems in the framework of relativity theory.