For the first time,we derive the compact forms of normalization factors for photon-added(-subtracted) two-mode squeezed thermal states by using the P-representation and the integration within an ordered product of o...For the first time,we derive the compact forms of normalization factors for photon-added(-subtracted) two-mode squeezed thermal states by using the P-representation and the integration within an ordered product of operators(IWOP) technique.It is found that these two factors are related to the Jacobi polynomials.In addition,some new relationships for Jacobi polynomials are presented.展开更多
Based on the Wigner-function method, we investigate the parity detection and phase sensitivity in a Mach–Zehnder interferometer(MZI) with two-mode squeezed thermal state(TMSTS). Using the classical transformation rel...Based on the Wigner-function method, we investigate the parity detection and phase sensitivity in a Mach–Zehnder interferometer(MZI) with two-mode squeezed thermal state(TMSTS). Using the classical transformation relation of the MZI, we derive the input–output Wigner functions and then obtain the explicit expressions of parity and phase sensitivity.The results from the numerical calculation show that supersensitivity can be reached only if the input TMSTS have a large number photons.展开更多
We study a system consisting of two identical non-interacting single-mode cavity fields coupled to a common vacuum environment and provide general,explicit,and exact solutions to its master equation by means of the ch...We study a system consisting of two identical non-interacting single-mode cavity fields coupled to a common vacuum environment and provide general,explicit,and exact solutions to its master equation by means of the characteristic function method.We analyze the entanglement dynamics of two-mode squeezed thermal state in this model and show that its entanglement dynamics is strongly determined by the two-mode squeezing parameter and the purity.In particular,we find that two-mode squeezed thermal state with the squeezing parameter r ≤-(l/2)ln √u is extremely fragile and almost does not,survive in a common vacuum environment.We investigate the time evolution of nonlocality for two-mode squeezed thermal state in such an environment.It is found that the evolved state loses its nonlocality in the beginning of the evolution,but after a time,the revival of nonlocality can occur.展开更多
For the beam splitter attack strategy against quantum key distribution using two-mode squeezed states, the analytical expression of the optimal beam splitter parameter is provided in this paper by applying the Shannon...For the beam splitter attack strategy against quantum key distribution using two-mode squeezed states, the analytical expression of the optimal beam splitter parameter is provided in this paper by applying the Shannon information theory. The theoretical secret information rate after error correction and privacy amplification is given in terms of the squeezed parameter and channel parameters. The results show that the two-mode squeezed state quantum key distribution is secure against an optimal beam splitter attack.展开更多
We explore how a two-mode squeezed vacuum state sechθeab tanh θ[00) evolves when it undergoes a single- mode amplitude dissipative channel with rate of decay k. We find that in this process not only the squeezing p...We explore how a two-mode squeezed vacuum state sechθeab tanh θ[00) evolves when it undergoes a single- mode amplitude dissipative channel with rate of decay k. We find that in this process not only the squeezing parameter decreases, tanhθ → e-kt tanh θ, but also the second-mode vacuum state evolves into a chaotic state exp{bbln[(1 - e-2kt) tanh2 θ]}. The outcome state is no more a pure state, but an entangled mixed state.展开更多
The result of one-mode quadrature-amplitude measurement for some generalized two-mode squeezed states has been studied by virtue of the entangled state representation of the corresponding two-mode squeezing operators....The result of one-mode quadrature-amplitude measurement for some generalized two-mode squeezed states has been studied by virtue of the entangled state representation of the corresponding two-mode squeezing operators. We find that the remaining fleld-mode simultaneously collapses to the single-mode squeezed state with more stronger squeezing. The measurement result caused by a single-mode squeezed state projector is also calculated, which indicates quantum entanglement in squeezing.展开更多
In this paper, we introduce a flexible model for the control and measurement of NAMRs (nanomechanical resonators). We obtain the free Hamiltonian of the dcSQUID (direct current superconducting quantum interference ...In this paper, we introduce a flexible model for the control and measurement of NAMRs (nanomechanical resonators). We obtain the free Hamiltonian of the dcSQUID (direct current superconducting quantum interference device) and the interaction Hamiltonian between these two NAMRs and the dc-SQUID by introducing the annihilation and creation operators under the rotating wave approximation. We can treat the mode of the dc-SQUID as a classical field. In the Heisenberg picture, the generation of two-mode squeezed states of two nanomechanical resonators is shown by their collective coordinate and momentum operators.展开更多
The q-analogues of two-mode squeezed states are introduced by virtue of deformation quantization methods and the technique of integration within an ordered product (IWOP) of operators. Some new completeness relation...The q-analogues of two-mode squeezed states are introduced by virtue of deformation quantization methods and the technique of integration within an ordered product (IWOP) of operators. Some new completeness relations about these squeezed states composed of the bra and ket which are not mutually Hermitian conjugates are obtained. Furthermore, the antibunching effects of the two-mode squeezed vacuum state S's(τ) │00) are investigated. It is found that, in different ranges of the squeezed parameter τ, both modes of the state exhibit the antibunching effects and the two modes of the state are always nonclassical correlation.展开更多
We investigate photon statistical properties of the multiple-photon-added two-mode squeezed coherent states (PA- TMSCS). We find that the photon statistical properties are sensitive to the compound phase involved in...We investigate photon statistical properties of the multiple-photon-added two-mode squeezed coherent states (PA- TMSCS). We find that the photon statistical properties are sensitive to the compound phase involved in the TMSCS. Our numerical analyses show that the photon addition can enhance the cross-correlation and anti-bunching effects of the PA- TMSCS. Compared with that of the TMSCS, the photon number distribution of the PA-TMSCS is modulated by a factor that is a monotonically increasing function of the numbers of adding photons to each mode; further, that the photon addition essentially shifts the photon number distribution.展开更多
Based on the fact that a two-mode squeezed number state is a two-variable Hermite polynomial excitation of the two-mode squeezed vacuum state, the result of one-mode l-photon measurement for the two-mode squeezed numb...Based on the fact that a two-mode squeezed number state is a two-variable Hermite polynomial excitation of the two-mode squeezed vacuum state, the result of one-mode l-photon measurement for the two-mode squeezed number state S2|m, n) is discussed. It is found that a remaining field-mode simultaneously collapses into a number state |n - m+l| with the coefficient being a Jacobi polynomial of n, m and l, which manifestly exhibits the entanglement between the two modes, i.e. it depends on the number-difference between the two modes. The second mode collapses into an excited coherent state when the first mode is measured as a coherent state.展开更多
For the first time, we derive the photon number cumulant for two-mode squeezed state and show that its cumulant expansion leads to normalization of two-mode photon subtracted-squeezed states and photon added- squeezed...For the first time, we derive the photon number cumulant for two-mode squeezed state and show that its cumulant expansion leads to normalization of two-mode photon subtracted-squeezed states and photon added- squeezed states. We show that the normalization is related to Jacobi polynomial, so the cumulant expansion in turn represents the new generating function of Jacobi polynomial.展开更多
We introduce the coordinate-dependent one-and two-mode squeezing transformations and discuss theproperties of the corresponding one-and two-mode squeezed states.We show that the coordinate-dependent one-and two-mode s...We introduce the coordinate-dependent one-and two-mode squeezing transformations and discuss theproperties of the corresponding one-and two-mode squeezed states.We show that the coordinate-dependent one-and two-mode squeezing transformations can be constructed by the combination of two transformations,a coordinate-dependentdisplacement followed by the standard squeezed transformation.Such a decomposition turns a nonlinear problem intoa linear one because all the calculations involving the nonlinear one- and two-mode squeezed transformation have beenshown to be able to reduce to those only concerning the standard one- and two-mode squeezed states.展开更多
We study genuine entanglement among three qubits undergoing a noisy process that includes dissipation, squeezing,and decoherence. We obtain a general solution and analyze the asymptotic quantum states. We find that mo...We study genuine entanglement among three qubits undergoing a noisy process that includes dissipation, squeezing,and decoherence. We obtain a general solution and analyze the asymptotic quantum states. We find that most of these asymptotic states can be genuinely entangled depending upon the parameters of the channel, memory parameter, and the parameters of the initial states. We study Greenberger–Horne–Zeilinger(GHZ) states and W states, mixed with white noise,and determine the conditions for them to be genuinely entangled at infinity. We find that for these mixtures, it is possible to start with a bi-separable state(with a specific mixture of white noise) and end with genuine entangled states. However, the memory parameter μ must be very high. We find that in contrast to the two-qubit case, none of the three-qubit asymptotic states for n → ∞ are genuinely entangled.展开更多
By using the technique of integration within an ordered product of operators, the normal ordered density operator of the photon-subtracted squeezed thermal state (PSSTS) is derived. Then the corresponding Wigner fun...By using the technique of integration within an ordered product of operators, the normal ordered density operator of the photon-subtracted squeezed thermal state (PSSTS) is derived. Then the corresponding Wigner function is presented by using the coherent state representation of the Wigner operator. The nonclassical properties of the PSSTS are discussed based on the negativity of the Wigner function.展开更多
We study the higher order fluctuations and squeezing of quadrature operators in the squeezed thermal states. In terms of measured phase operators, we discuss the fluctuations and squeezing of phases in these states....We study the higher order fluctuations and squeezing of quadrature operators in the squeezed thermal states. In terms of measured phase operators, we discuss the fluctuations and squeezing of phases in these states. We conclude that the condition of higher order squeezing for quadrature components of the field is order independent and the fluctuations of measured phase operators are temperature independent.展开更多
For the density operator(mixed state) describing squeezed chaotic light(SCL) we search for its thermal vacuum state(a pure state) in the real-fictitious space. Using the method of integration within ordered prod...For the density operator(mixed state) describing squeezed chaotic light(SCL) we search for its thermal vacuum state(a pure state) in the real-fictitious space. Using the method of integration within ordered product(IWOP) of operators we find that it is a kind of one- and two-mode combinatorial squeezed state. Its application in evaluating the quantum fluctuation of photon number reveals: the stronger the squeezing is, the larger a fluctuation appears. The second-order degree of coherence of SCL is also deduced which shows that SCL is classic. The new thermal vacuum state also helps to derive the Wigner function of SCL.展开更多
By analysing the properties of two-mode quadratures in an entangled state representation (ESR) we derive from ESR some complicated exponential quadrature operators for nonlinear two-mode squeezing, which directly le...By analysing the properties of two-mode quadratures in an entangled state representation (ESR) we derive from ESR some complicated exponential quadrature operators for nonlinear two-mode squeezing, which directly leads to wave function of the nonlinear squeezed state in ESR.展开更多
<Abstract>We study squeezed properties of magnon squeezed thermal spin states by using the distribution of Q function in the ferromagnet.It is found that the distribution of Q function strongly depends on the te...<Abstract>We study squeezed properties of magnon squeezed thermal spin states by using the distribution of Q function in the ferromagnet.It is found that the distribution of Q function strongly depends on the temperature T and coupling parameter γ.Below the transition temperature T_c,the distribution Q function in the squeezed thermal spin state presents a richer structure than in the normal state.Non-classical effects have been observed.In the transition from the normal to the squeezed thermal spin state,the phase symmetry of the magnon system is spontaneously broken.展开更多
Using the theory of thermal field dynamics (TFD), a model polariton system is investigated and the squeezing properties of the polariton system at finite temperature is discussed. It is shown that when the photon fiel...Using the theory of thermal field dynamics (TFD), a model polariton system is investigated and the squeezing properties of the polariton system at finite temperature is discussed. It is shown that when the photon field is initially in a thermal vacuum state and the phonon initially in its lowest energy level state (the vacuum state), the phonon, photon and also the polariton system can exhibit nonclassical behaviour.展开更多
By virtue of the entangled state representation (Hong-Yi Fan and J R Klauder 1994 Phys. Rev. A 49 704) and the two-mode squeezing operator's natural representation (Hong-Yi Fan and Yue Fan 1996 Phys. Rev. A 54 958...By virtue of the entangled state representation (Hong-Yi Fan and J R Klauder 1994 Phys. Rev. A 49 704) and the two-mode squeezing operator's natural representation (Hong-Yi Fan and Yue Fan 1996 Phys. Rev. A 54 958) we propose the squeeze-swapping mechanism which can generate quantum entanglement and new squeezed states of continuum variables.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11264018 and 60978009)the Major Research Plan of the National Natural Science Foundation of China (Grant No. 91121023)+1 种基金the National Basic Research Project of China (Grant No. 2011CBA00200)the Young Talents Foundation of Jiangxi Normal University,China
文摘For the first time,we derive the compact forms of normalization factors for photon-added(-subtracted) two-mode squeezed thermal states by using the P-representation and the integration within an ordered product of operators(IWOP) technique.It is found that these two factors are related to the Jacobi polynomials.In addition,some new relationships for Jacobi polynomials are presented.
基金supported by the National Natural Science Foundation of China(Grant No.11447002)the Research Foundation of the Education Department of Jiangxi Province of China(Grant No.GJJ150338)the Research Foundation for Changzhou Institute of Modern Optoelectronic Technology(Grant No.CZGY15)
文摘Based on the Wigner-function method, we investigate the parity detection and phase sensitivity in a Mach–Zehnder interferometer(MZI) with two-mode squeezed thermal state(TMSTS). Using the classical transformation relation of the MZI, we derive the input–output Wigner functions and then obtain the explicit expressions of parity and phase sensitivity.The results from the numerical calculation show that supersensitivity can be reached only if the input TMSTS have a large number photons.
基金Supported by Hunan Provincial Natural Science Foundation of China under Grant No.10JJ6010the Key Project Foundation of Hunan Provincial Education Department of China under Grant No.10A095
文摘We study a system consisting of two identical non-interacting single-mode cavity fields coupled to a common vacuum environment and provide general,explicit,and exact solutions to its master equation by means of the characteristic function method.We analyze the entanglement dynamics of two-mode squeezed thermal state in this model and show that its entanglement dynamics is strongly determined by the two-mode squeezing parameter and the purity.In particular,we find that two-mode squeezed thermal state with the squeezing parameter r ≤-(l/2)ln √u is extremely fragile and almost does not,survive in a common vacuum environment.We investigate the time evolution of nonlocality for two-mode squeezed thermal state in such an environment.It is found that the evolved state loses its nonlocality in the beginning of the evolution,but after a time,the revival of nonlocality can occur.
基金Project supported by the Shanghai Jiaotong University (SJTU) Young Teacher Foundation,China (Grant No A2831B)the SJTU Participating in Research Projects (PRPs),China (Grant No T03011030)the National Natural Science Foundation of China(Grant No 60472018)
文摘For the beam splitter attack strategy against quantum key distribution using two-mode squeezed states, the analytical expression of the optimal beam splitter parameter is provided in this paper by applying the Shannon information theory. The theoretical secret information rate after error correction and privacy amplification is given in terms of the squeezed parameter and channel parameters. The results show that the two-mode squeezed state quantum key distribution is secure against an optimal beam splitter attack.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11047133 and 10647133)the Natural Science Foundation of Jiangxi Province of China (Grant Nos. 2009GQS0080 and 2010GQW0027)the Research Foundation of the Education Department of Jiangxi Province of China (Grant Nos. GJJ11339 and GJJ10097)
文摘We explore how a two-mode squeezed vacuum state sechθeab tanh θ[00) evolves when it undergoes a single- mode amplitude dissipative channel with rate of decay k. We find that in this process not only the squeezing parameter decreases, tanhθ → e-kt tanh θ, but also the second-mode vacuum state evolves into a chaotic state exp{bbln[(1 - e-2kt) tanh2 θ]}. The outcome state is no more a pure state, but an entangled mixed state.
文摘The result of one-mode quadrature-amplitude measurement for some generalized two-mode squeezed states has been studied by virtue of the entangled state representation of the corresponding two-mode squeezing operators. We find that the remaining fleld-mode simultaneously collapses to the single-mode squeezed state with more stronger squeezing. The measurement result caused by a single-mode squeezed state projector is also calculated, which indicates quantum entanglement in squeezing.
基金supported by the Natural Science Foundation of Hebei Province (No. A2006000299)KeyProgram of Science and Technolgy of Hebei Province (No. 06547003D-1)
文摘In this paper, we introduce a flexible model for the control and measurement of NAMRs (nanomechanical resonators). We obtain the free Hamiltonian of the dcSQUID (direct current superconducting quantum interference device) and the interaction Hamiltonian between these two NAMRs and the dc-SQUID by introducing the annihilation and creation operators under the rotating wave approximation. We can treat the mode of the dc-SQUID as a classical field. In the Heisenberg picture, the generation of two-mode squeezed states of two nanomechanical resonators is shown by their collective coordinate and momentum operators.
基金Project supported by the National Natural Science Foundation of China (Grant No 10574060)the Natural Science Foundation of Liaocheng University of China (Grant No X071049)
文摘The q-analogues of two-mode squeezed states are introduced by virtue of deformation quantization methods and the technique of integration within an ordered product (IWOP) of operators. Some new completeness relations about these squeezed states composed of the bra and ket which are not mutually Hermitian conjugates are obtained. Furthermore, the antibunching effects of the two-mode squeezed vacuum state S's(τ) │00) are investigated. It is found that, in different ranges of the squeezed parameter τ, both modes of the state exhibit the antibunching effects and the two modes of the state are always nonclassical correlation.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.11174114 and 61107055)the Natural Science Foundation of Wuxi Institute of Technology of China (Grant No.401301293)
文摘We investigate photon statistical properties of the multiple-photon-added two-mode squeezed coherent states (PA- TMSCS). We find that the photon statistical properties are sensitive to the compound phase involved in the TMSCS. Our numerical analyses show that the photon addition can enhance the cross-correlation and anti-bunching effects of the PA- TMSCS. Compared with that of the TMSCS, the photon number distribution of the PA-TMSCS is modulated by a factor that is a monotonically increasing function of the numbers of adding photons to each mode; further, that the photon addition essentially shifts the photon number distribution.
基金Project supported by the National Natural Science Foundation of China (Grant No 10774108)
文摘Based on the fact that a two-mode squeezed number state is a two-variable Hermite polynomial excitation of the two-mode squeezed vacuum state, the result of one-mode l-photon measurement for the two-mode squeezed number state S2|m, n) is discussed. It is found that a remaining field-mode simultaneously collapses into a number state |n - m+l| with the coefficient being a Jacobi polynomial of n, m and l, which manifestly exhibits the entanglement between the two modes, i.e. it depends on the number-difference between the two modes. The second mode collapses into an excited coherent state when the first mode is measured as a coherent state.
基金Project supported by the Natural Science Foundation of Fujian Province,China (Grant No.2011J01018)the National Natural Science Foundation of China (Grant No.11175113)
文摘For the first time, we derive the photon number cumulant for two-mode squeezed state and show that its cumulant expansion leads to normalization of two-mode photon subtracted-squeezed states and photon added- squeezed states. We show that the normalization is related to Jacobi polynomial, so the cumulant expansion in turn represents the new generating function of Jacobi polynomial.
文摘We introduce the coordinate-dependent one-and two-mode squeezing transformations and discuss theproperties of the corresponding one-and two-mode squeezed states.We show that the coordinate-dependent one-and two-mode squeezing transformations can be constructed by the combination of two transformations,a coordinate-dependentdisplacement followed by the standard squeezed transformation.Such a decomposition turns a nonlinear problem intoa linear one because all the calculations involving the nonlinear one- and two-mode squeezed transformation have beenshown to be able to reduce to those only concerning the standard one- and two-mode squeezed states.
文摘We study genuine entanglement among three qubits undergoing a noisy process that includes dissipation, squeezing,and decoherence. We obtain a general solution and analyze the asymptotic quantum states. We find that most of these asymptotic states can be genuinely entangled depending upon the parameters of the channel, memory parameter, and the parameters of the initial states. We study Greenberger–Horne–Zeilinger(GHZ) states and W states, mixed with white noise,and determine the conditions for them to be genuinely entangled at infinity. We find that for these mixtures, it is possible to start with a bi-separable state(with a specific mixture of white noise) and end with genuine entangled states. However, the memory parameter μ must be very high. We find that in contrast to the two-qubit case, none of the three-qubit asymptotic states for n → ∞ are genuinely entangled.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10775097 and 10874174)the Research Foundation of the Education Department of Jiangxi Province of China
文摘By using the technique of integration within an ordered product of operators, the normal ordered density operator of the photon-subtracted squeezed thermal state (PSSTS) is derived. Then the corresponding Wigner function is presented by using the coherent state representation of the Wigner operator. The nonclassical properties of the PSSTS are discussed based on the negativity of the Wigner function.
文摘We study the higher order fluctuations and squeezing of quadrature operators in the squeezed thermal states. In terms of measured phase operators, we discuss the fluctuations and squeezing of phases in these states. We conclude that the condition of higher order squeezing for quadrature components of the field is order independent and the fluctuations of measured phase operators are temperature independent.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.1117511311447202and 11574295)
文摘For the density operator(mixed state) describing squeezed chaotic light(SCL) we search for its thermal vacuum state(a pure state) in the real-fictitious space. Using the method of integration within ordered product(IWOP) of operators we find that it is a kind of one- and two-mode combinatorial squeezed state. Its application in evaluating the quantum fluctuation of photon number reveals: the stronger the squeezing is, the larger a fluctuation appears. The second-order degree of coherence of SCL is also deduced which shows that SCL is classic. The new thermal vacuum state also helps to derive the Wigner function of SCL.
基金supported by the National Natural Science Foundation of China (Grant No.10904033)the Natural Science Foundation of Hubei Province,China (Grant No.2009CDA145)
文摘By analysing the properties of two-mode quadratures in an entangled state representation (ESR) we derive from ESR some complicated exponential quadrature operators for nonlinear two-mode squeezing, which directly leads to wave function of the nonlinear squeezed state in ESR.
基金supported by National Natural Science Foundation of China under Grant Nos.10174024 and 10474025
文摘<Abstract>We study squeezed properties of magnon squeezed thermal spin states by using the distribution of Q function in the ferromagnet.It is found that the distribution of Q function strongly depends on the temperature T and coupling parameter γ.Below the transition temperature T_c,the distribution Q function in the squeezed thermal spin state presents a richer structure than in the normal state.Non-classical effects have been observed.In the transition from the normal to the squeezed thermal spin state,the phase symmetry of the magnon system is spontaneously broken.
文摘Using the theory of thermal field dynamics (TFD), a model polariton system is investigated and the squeezing properties of the polariton system at finite temperature is discussed. It is shown that when the photon field is initially in a thermal vacuum state and the phonon initially in its lowest energy level state (the vacuum state), the phonon, photon and also the polariton system can exhibit nonclassical behaviour.
基金Project supported by the Doctoral Scientific Research Startup Fund of Anhui University,China (Grant No. 33190059)the National Natural Science Foundation of China (Grant No. 10874174)the Research Fund for the Doctoral Program of Higher Education of China (New Teacher) (Grant No. 20113401120004)
文摘By virtue of the entangled state representation (Hong-Yi Fan and J R Klauder 1994 Phys. Rev. A 49 704) and the two-mode squeezing operator's natural representation (Hong-Yi Fan and Yue Fan 1996 Phys. Rev. A 54 958) we propose the squeeze-swapping mechanism which can generate quantum entanglement and new squeezed states of continuum variables.