共查询到20条相似文献,搜索用时 78 毫秒
1.
算符a^K本征态热迭加光场的光子数统计分布 总被引:1,自引:0,他引:1
利用密度矩阵方法,导出了光子湮没算符高次幂a^K(k≥2)本征态热迭加光场光子数统计分布的一般表达式,讨论了热噪声对非经典光场态光数统计分布振荡行为的影响。 相似文献
2.
Jun Zhou Jun Song Hao Yuan Bo Zhang Chuan-Mei Xie Hong-Yi Fan 《International Journal of Theoretical Physics》2012,51(9):2681-2689
In this paper, we present the density operator of the generalized squeezed thermal state (GSTS) and obtain its normal ordering form by virtue of the technique of integration within an ordered product of operators and the Weyl ordering invariance under similarity transformations. Some significant quantum statistical properties of the GSTS are investigated, such as the photon-number distribution (PND) and the Wigner function (WF). It is found that the PND of the GSTS is a Legendre polynomial, and its squeezed vacuum oscillations imply the nonclassicality, as well as the GSTS whose WF has no negative region is indeed a special type of nonclassical state. 相似文献
3.
Photon-Subtracted Two-Mode Squeezed Thermal State and Its Photon-Number Distribution 总被引:1,自引:0,他引:1
We construct the photon-subtracted two-mode squeezed thermal state (PSTMSTS) by subtracting any number of photons from two-mode
squeezed thermal state (TMSTS). It is found that the normalization factor of the density operator of PSTMSTS is a Jacobi polynomial
of squeezing parameter λ and average photon number [`(n)]\bar{n} of the thermal state. We investigate the photon-number distribution (PND) of PSTMSTS and find a remarkable result that it
is a quotient of two Jacobi polynomials, as well as derive a corresponding character of Jacobi polynomial. 相似文献
4.
New approach for deriving the exact time evolution of the density operator for a diffusive anharmonic oscillator and its Wigner distribution function
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Using thermal entangled state representation,we solve the master equation of a diffusive anharmonic oscillator(AHO) to obtain the exact time evolution formula for the density operator in the infinitive operator-sum representation.We present a new evolution formula of the Wigner function(WF) for any initial state of the diffusive AHO by converting the WF calculation into an overlap between two pure states in an enlarged Fock space.It is found that this formula is very convenient in investigating the WF’s evolution of any known initial state.As applications,this formula is used to obtain the evolution of the WF for a coherent state and the evolution of the photon-number distribution of diffusive AHOs. 相似文献
5.
Using the thermal field dynamics theory to convert the thermal state into a "pure" state in doubled Fock space, we find that the average value of efa a under squeezed thermal state (STS) is just the generating function of Legendre polynomials. Based on this remarkable result, the normalization and photon-number distributions of m-photon added (or subtracted) STSs are conviently obtained as the Legendre polynomials. This new concise method can be expanded to the entangled case. 相似文献
6.
New approach for deriving the exact time evolution of density operator for diffusive anharmonic oscillator and its Wigner distribution function
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Using the thermal entangled state representation, we solve the master equation of a diffusive anharmonic oscillator (AHO) to obtain the exact time evolution formula for the density operator in the infinitive operator-sum representation. We present a new evolution formula of the Wigner function (WF) for any initial state of the diffusive AHO by converting the calculation of the WF to an overlap between two pure states in an enlarged Fock space. It is found that this formula brings us much convenience to investigate the WF's evolution of any known initial state. As applications, this formula is used to obtain the evolution of the WF for a coherent state and the evolution of the photon-number distribution of the diffusive AHO. 相似文献
7.
We construct a new type of photon-added squeezed coherent state generated by repeatedly operating the bosonic creation operator on a new type of squeezed coherent state [Fan H Y and Xiao M 1996 Phys. Lett. A 220 81]. We find that its normalization factor is related to single-variable Hermite polynomials. Furthermore, we investigate its statistical properties, such as Mandel’s Q parameter, photon-number distribution, and Wigner function. The nonclassicality is displayed in terms of the intense oscillation of photon-number distribution and the negativity of the Wigner function. 相似文献
8.
B. Mojaveri A. Dehghani M. A. Fasihi T. Mohammadpour 《International Journal of Theoretical Physics》2018,57(11):3396-3409
In this paper, we consider a Hamiltonian model that includes interaction of two coupled two-level atoms with a single-mode quantized electromagnetic field in a cavity via the degenerate two-photon transition. The cavity is filled with a Kerr-like medium and is held at a temperature T. The free field Hamiltonian possesses the su(1,1) symmetry which realized by either even or odd photon-number states. The total number of excitation as a constant of motion, provides a decomposition of the Hilbert space of system into direct sums of invariant subspaces. As a results, the representation of the Hamiltonian becomes block-diagonal matrix with three blocks. After diagonalizing each block, we obtain thermal state of system in the whole Hilbert space and within its excitation subspaces. Finally, the effect of temperature, atom-atom and Kerr-type couplings on the degree of thermal entanglement between the atoms are investigated. Our results show that within the single-excitation subspace spanned with odd photon-number states, the entanglement between the atoms is thermally robust. 相似文献
9.
From the normally ordered form of the density operator of a squeezed coherent state(SCS),we directly derive the compact expression of the SCS’s photon-number distribution(PND).Besides the known oscillation characteristics,we find that the PND is a periodic function with a period of π and extremely sensitive to phase.If the squeezing is strong enough,and the compound phase which is relevant to the complex squeezing and displacement parameters are assigned appropriate values,different oscillation behaviours in PND for even and odd photon numbers appear,respectively. 相似文献
10.
Jeong-Ryeol Choi 《Pramana》2003,61(1):7-20
Taking advantage of dynamical invariant operator, we derived quantum mechanical solution of general time-dependent harmonic
oscillator. The uncertainty relation of the system is always larger than ħ/2 not only in number but also in the thermal state
as expected. We used the diagonal elements of density operator satisfying Leouville-von Neumann equation to calculate various
expectation values in the thermal state. We applied our theory to a special case which is the forced Caldirola-Kanai oscillator. 相似文献
11.
M. Sebawe Abdalla F.A.A. El-Orany J. Peřina 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):423-438
In the present paper we introduce a new squeeze operator, which is related to the time-dependent evolution operator for Hamiltonian
representing mutual interaction between three different modes. Squeezing phenomenon as well as the variances of the photon-number
sum and difference are considered. Moreover, Glauber second-order correlation function is discussed, besides the quasiprobability
distribution function and phase distribution for different states. The joint photon-number distribution is also reported.
Received 29 March 2000 and Received in final form 20 September 2000 相似文献
12.
13.
Consider a quantum system S weakly interacting with a very large but finite system B called the heat bath, and suppose that the composite S∪B is in a pure state Ψ with participating energies between E and E+δ with small δ. Then, it is known that for most Ψ the reduced density matrix of S is (approximately) equal to the canonical density matrix. That is, the reduced density matrix is universal in the sense that it depends only on S’s Hamiltonian and the temperature but not on B’s Hamiltonian, on the interaction Hamiltonian, or on the details of Ψ. It has also been pointed out that S can also be attributed a random wave function ψ whose probability distribution is universal in the same sense. This distribution is known as the “Scrooge measure” or “Gaussian adjusted projected (GAP) measure”; we regard it as the thermal equilibrium distribution of wave functions. The relevant concept of the wave function of a subsystem is known as the “conditional wave function.” In this paper, we develop analogous considerations for particles with spin. One can either use some kind of conditional wave function or, more naturally, the “conditional density matrix,” which is in general different from the reduced density matrix. We ask what the thermal equilibrium distribution of the conditional density matrix is, and find the answer that for most Ψ the conditional density matrix is (approximately) deterministic, in fact (approximately) equal to the canonical density matrix. 相似文献
14.
The Schrödinger equation of the mesoscopic capacitance coupled circuit with an arbitrary power source is solved by means of two step unitary transformation. The original Hamiltonian transformed to a very simple form by unitary operators so that it can be easily treated. We derived the exact full wave functions in Fock state. By making use of these wave functions and introducing the Lewis--Riesenfeld invariant operator, the thermal state have been constructed. The fluctuations of charges and currents are evaluated in thermal state. For T→ 0, the uncertainty products between charges and currents in thermal state recovers exactly to that of Fock state with n, m=0. 相似文献
15.
Evolution formulas of the density operator, the photon number distribution, and the Wigner function are derived for the problem on the optical fields propagation in realistic environments. Using the idea “reservoir modeled by beam splitter (BS)” and the Weyl expansion of the density operator, we obtain these formulas cleverly, which are very useful for quantum optics and quantum statistics. As an application, we study the time evolution of the photon number distribution and the Wigner function for single-photon-added coherent state in thermal environment. 相似文献
16.
Thermal Wigner Operator in Coherent Thermal State Representation and Its Application 总被引:1,自引:0,他引:1
FANHong-Yi 《理论物理通讯》2002,37(3):289-292
In the coherent thermal state representation we introduce thermal Wigner operator and find that it is “squeezed” under the thermal transformation.The thermal Wigner operator provides us with a new direct and neat approach for deriving Wigner functions of thermal states. 相似文献
17.
We employ the coherent thermal states (a kind of entangled states) in thermal field dynamics to establish a complete entangled state formalism expressing pseudo-classical representations of density operator for light field.Especially, the relationship between the coherent thermal state and the characteristic function and the positive P representation in quantum optics theory are obtained. 相似文献
18.
We employ the coherent thermal states
(a kind of entangled states) in
thermal field dynamics to establish a complete entangled state formalism
expressing pseudo-classical representations of density operator for light field. Especially, the relationship between the coherent thermal state and the characteristic function and the positive P representation in quantum
optics theory are obtained. 相似文献
19.
Xiang-Guo Meng Ji-Suo Wang Hua-Chao Gao 《International Journal of Theoretical Physics》2016,55(8):3630-3636
Exploiting the thermo entangled state approach, we successfully solve the master equation for describing the single-mode cavity driven by an oscillating external field in the heat reservoir and then get the analytical time-evolution rule for the density operator in the infinitive Kraus operator-sum representation. It is worth noting that the Kraus operator M l, m is proved to be a trace-preserving quantum operation. As an application, the time-evolution for an initial coherent state ρ |β〉 = |β〉〈β| in such an environment is investigated, which shows that the initial coherent state decays to a new mixed state as a result of thermal noise, however the coherence can still be reserved for amplitude damping. 相似文献
20.
We analytically study the Wigner function (WF) for the two-variable Hermite polynomial state (TVHPS) and the effect of decoherence on the TVHPS in thermal environment. The nonclassicality of the TVHPS is investigated in terms of the partial negativity of the WF which depends on the polynomial orders m,n and the squeezing parameter r. We also investigate how the WF for the TVHPS evolves in the thermal environment. At long times, the TVHPS decays to thermal, a mixed Gaussian state, within the thermal environment. 相似文献