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1.
In this Letter, the “number-phase entropic uncertainty relation” and the “number-phase Wigner function” of generalized coherent states associated to a few solvable quantum systems with non-degenerate spectra are studied. We also investigate time evolution of “number-phase entropic uncertainty” and “Wigner function” of the considered physical systems with the help of temporally stable Gazeau-Klauder coherent states. 相似文献
2.
Shuai Wang 《International Journal of Theoretical Physics》2009,48(5):1459-1465
For L-C circuit, a new quantized scheme has been proposed in the context of number-phase quantization. In this quantization
scheme, the number n of the electric charge q(q=en) is quantized as the charge number operator and the phase difference θ across the capacity is quantized as phase operator. Based on the scheme of number-phase quantization and the thermo field
dynamics (TFD), the quantum fluctuations of the charge number and phase difference of a mesoscopic L-C circuit in the thermal
vacuum state, the thermal coherent state and the thermal squeezed state have been studied. It is shown that these quantum
fluctuations of the charge number and phase difference are related to not only the parameters of circuit, the squeezing parameter,
but also the temperature in these quantum states. It is proven that the number-phase quantization scheme is very useful to
tackle with quantization of some mesoscopic electric circuits and the quantum effects. 相似文献
3.
In this paper, the generalized coherent state for quantum systems with degenerate spectra is introduced. Then, the nonclassicality features and number-phase entropic uncertainty relation of two particular degenerate quantum systems are studied. Finally, using the Gazeau-Klauder coherent states approach, the time evolution of some of the nonclassical properties of the coherent states corresponding to the considered physical systems are discussed. 相似文献
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The paper shows that the Wigner distribution function of quantum optical coherent states, or of a superposition of such states, can be produced and measured with a classical optical set-up using classical coherent light fields. This measurement cannot be done directly in quantum optics since the quantum phase space variables correspond to non-commuting operators. As an example, the Wigner distribution function of Schrödinger cat states of light has been measured. It is also shown that the possibility of measuring the Wigner distribution function of quantum coherent states with classical coherent fields is unique in the sense that it cannot be extended to other quantum states, not even to the incoherent limit of the superposition of coherent states. 相似文献
8.
R. Srikanth S. Banerjee 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):217-227
We develop an information theoretic interpretation of the number-phase complementarity in atomic systems, where phase is treated
as a continuous positive operator valued measure (POVM). The relevant uncertainty principle is obtained as an upper bound
on a sum of knowledge of these two observables for the case of two-level systems. A tighter bound characterizing the uncertainty
relation is obtained numerically in terms of a weighted knowledge sum involving these variables. We point out that complementarity
in these systems departs from mutual unbiasededness in two significant ways: first, the maximum knowledge of a POVM variable
is less than log (dimension) bits; second, surprisingly, for higher dimensional systems, the unbiasedness may not be mutual
but unidirectional in that phase remains unbiased with respect to number states, but not vice versa. Finally, we study the
effect of non-dissipative and dissipative noise on these complementary variables for a single-qubit system. 相似文献
9.
Recently, nonlocality and Bell inequalities have been used to investigate quantum phase transitions (QPTs) in low-dimensional quantum systems. Nonlocality can be detected by the Bell-Clauser-Horne-Shimony-Holt (Bell-CHSH) function. In this work, we extend the study of the Bell-CHSH function (BCF) to QPTs in matrix product systems (MPSs). In these kinds of QPTs, the ground-state energy remains analytical in the vicinity of the QPT points, and they are usually called MPS-QPTs. For several typical models, our results show that the BCF can signal MPS-QPTs very well. In addition, we find the BCF can capture signal of QPTs in unentangled states and classical states, for which other measures of quantum correlation (quantum entanglement and quantum discord) fail. Furthermore, we find that in these MPSs, there exists some kind of quantum correlation which cannot be characterized by entanglement, or by nonlocality. 相似文献
10.
根据Pegg-Barnett 相位定义,计算了一种新的非线性叠加相干态的相位概率分布函数和光子数-相位压缩效应,并进行了数值模拟. 相似文献
11.
《Annals of Physics》1987,176(1):1-21
For a non-relativistic system with only continous degrees of freedom (no spin, for example), the original Wigner function can be used as an alternative to the density matrix to represent an arbitrary quantum state. Indeed, the quantum mechanics of such systems can be formulated entirely in terms of the Wigner function and other functions on phase space, with no mention of state vectors or operators. In the present paper this Wigner-function formulation is extended to systems having only a finite number of orthogonal states. The “phase space” for such a system is taken to be not continuous but discrete. In the simplest cases it can be pictured as an N×N array of points, where N is the number of orthogonal states. The Wigner function is a real function on this phase space, defined so that its properties are closely analogous to those of the original Wigner function. In this formulation, observables, like states, are represented by real functions on the discrete phase space. The complex numbers still play an important role: they appear in an essential way in the rule for forming composite systems. 相似文献
12.
LIANG Bao-Long WANG Ji-Suo MENG Xiang-Guo 《理论物理通讯》2008,49(1):88-92
In this paper, the number-phase quantization scheme of the mesoscopic circuit, which consists of a singlequbit structure with superconducting quantum interference device coupled with a super-conducting resonator, is given. By introducing a unitary matrix and by means of spectral decomposition, the Hamiltonian operator of the system is exactly formulated in compact forms in spin-l/2 notation. The eigenvalues and the eigenstates of the system are investigated. It is found that using this system the entangled states can not only be prepared, but also be manipulated by tuning the magnetic flux through the super-conducting loop. 相似文献
13.
It is shown that Gaussian superpositions of coherent states along an arc are approximate number-phase intelligent states associated with the Pegg-Barnett phase operator and describe amplitude squeezing. 相似文献
14.
Masashi Ban 《International Journal of Theoretical Physics》1996,35(9):1947-1992
A phase-space representation of quantum systems within the framework of the relative-state formulation is proposed. To this end, relative-position and relative-momentum states are introduced and their properties are investigated in detail. Phase-space functions that represent a quantum state vector are constructed in terms of the relative-positive and relative-momentum states, and the quantum dynamics is investigated by using the phase-space functions. Furthermore, probability distributions in phase space are considered by means of the relativestate formulation, and it is shown that the phase-space probability distribution is closely related to the operational probability distribution. The marginal distribution, characteristic function, and operational uncertainty relation are also discussed. 相似文献
15.
《Physics letters. [Part B]》1999,466(1):27-32
In this paper the angle-angular momentum entropic uncertainty relations are obtained for Tsallis-like entropies for nonextensive quantum scattering of spinless particles. The number-phase entropic uncertainty relations are also proved for nonextensive quantum scattering. Numerical results on the experimental tests of these entropic uncertainty relations, for the nonextensive (q≠1) statistics case are obtained by calculations of Tsallis-like scattering entropies from the 48 experimental sets of the pion-nucleus phase shifts. 相似文献
16.
C. Wetterich 《Physics letters. A》2012,376(5):706-712
We describe both quantum particles and classical particles in terms of a classical statistical ensemble, with a probability distribution in phase space. By use of a wave function in phase space both can be treated in the same quantum formalism. Quantum particles are characterized by a specific choice of observables and time evolution of the probability density. Then interference and tunneling are found within classical statistics. Zwitters are (effective) one-particle states for which the time evolution interpolates between quantum and classical particles. Experimental bounds on a small parameter can test quantum mechanics. 相似文献
17.
A. V. Chizhov A. A. Gusev L. A. Sevastianov S. I. Vinitsky 《Physics of Particles and Nuclei Letters》2007,4(2):197-199
We propose a new method for describing phase distributions of nonclassical states in optical systems based on the nonnegative
quantum distribution function. A comparison of the proposed method with other known methods such as the Pegg-Barnett and operational
ones is given.
The text was submitted by the authors in English. 相似文献
18.
Nontrivial symmetry of order parameters is crucial in some of the most interesting quantum many-body states of ultracold atoms as well as condensed matter systems. Examples in cold atoms include p-wave Feshbach molecules and d-wave paired states of fermions that could be realized in optical lattices in the Hubbard regime. Identifying these states in experiments requires measurements of the relative phase of different components of the entangled pair wave function. We propose and discuss two schemes for such phase-sensitive measurements, based on two-particle interference revealed in atom-atom or atomic density correlations. Our schemes can also be used for relative phase measurements for nontrivial particle-hole order parameters, such as d-density wave order. 相似文献
19.
Quantum phase distribution and the number—phase Wigner function of the generalized squeezed vacuum states associated with solvable quantum systems
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The quantum phase properties of the generalized squeezed vacuum states associated with solvable quantum systems are studied by using the Pegg-Barnett formalism.Then,two nonclassical features,i.e.,squeezing in the number and phase operators,as well as the number-phase Wigner function of the generalized squeezed states are investigated.Due to some actual physical situations,the present approach is applied to two classes of generalized squeezed states:solvable quantum systems with discrete spectra and nonlinear squeezed states with particular nonlinear functions.Finally,the time evolution of the nonclassical properties of the considered systems has been numerically investigated. 相似文献
20.
In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggest the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum–atom optics to treat fermionic systems is rather rare, though fermion coherent states using Grassmann variables are widely used in particle physics. 相似文献