- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Lower- and Higher-Order Nonclassical Properties of Photon Added and Subtracted Displaced Fock States
摘要： Nonclassical properties of photon added and subtracted displaced Fock states are studied using various witnesses of lower- and higher-order nonclassicality. Compact analytic expressions are obtained for the nonclassicality witnesses. Using those expressions, it is established that these states and the states that can be obtained as their limiting cases (except coherent states) are highly nonclassical as they show the existence of lower- and higher-order antibunching and sub-Poissonian photon statistics, in addition to the nonclassical features revealed through the Mandel QM parameter, zeros of Q function, Klyshko’s criterion, and Agarwal–Tara criterion. Further, some comparison between the nonclassicality of photon added and subtracted displaced Fock states have been performed using witnesses of nonclassicality. This has established that between the two types of non-Gaussianity inducing operations (i.e., photon addition and subtraction) used here, photon addition influences the nonclassical properties more strongly. Further, optical designs for the generation of photon added and subtracted displaced Fock states from squeezed vacuum state have also been proposed.
关键词： photon added displaced Fock state,quantum state engineering,higher-order nonclassicality,photon subtracted displaced Fock state
更新于2025-09-23 15:23:52
-
Gaussian channels that are eventually entanglement breaking yet asymptotically nonclassicality saving
摘要： A complete classification of single-mode bosonic Gaussian channels on the basis of being quantum-limited or entanglement breaking under n-fold composition is obtained. Parametric forms for all single-mode bosonic Gaussian channels that remain quantum-limited under n-fold composition is obtained. It is shown that the obtained parametric forms of quantum-limited amplifier, attenuator, and singular noise channels are entanglement saving, i.e., they do not break entanglement under finite n-fold composition. All other single-mode bosonic Gaussian channels, quantum limited or not, are shown to be eventually entanglement breaking. Nonclassicality breaking under multiple composition of a single-mode bosonic Gaussian channel is also studied. We outline a family of single-mode bosonic Gaussian channels that are eventually entanglement breaking, but asymptotically nonclassicality saving. We illustrate examples of channels that are eventually nonclassicality breaking, asymptotically nonclassicality breaking, and asymptotically nonclassicality saving.
关键词： quantum-limited,entanglement breaking,asymptotically nonclassicality saving,Gaussian channels,nonclassicality breaking
更新于2025-09-23 15:21:01
-
Wehrl entropy based quantification of nonclassicality for single mode quantum optical states
摘要： Nonclassical states of a quantized light are described in terms of Glauber-Sudarshan P distribution which is not a genuine classical probability distribution. Despite several attempts, defining a uniform measure of nonclassicality (NC) for the single mode quantum states of light is yet an open task. In our previous work [Phys. Rev. A 95, 012330 (2017)] we have shown that the existing well-known measures fail to quantify the NC of single mode states that are generated under multiple NC-inducing operations. In this paper, we propose a new quantification of NC for the single mode quantum states as the difference between the total Wehrl entropy of the state and the maximum Wehrl entropy arising due to its classical characteristics. The classical reference state is chosen at the same randomness, given by the von-Neumann entropy, as the state itself. We further suggest operational interpretation of the proposed measure in terms of phase-space sampling entropy as well as potential to generate entanglement, in the case of pure states. We obtain analytic expressions of NC for pure states and Gaussian mixed states. We show that, along with the states generated under single NC-inducing operations, also for the broader class of states that are generated under multiple NC-inducing operations, our quantification enumerates the NC consistently. However, the evaluation of NC for the non-Gaussian mixed states is subject to extensive numerical computation that lies beyond the scope of the current work. We finally conclude with certain open questions.
关键词： Wehrl Entropy,Quantumness,Phase Space Distributions,Quantum Optics,Nonclassicality
更新于2025-09-23 15:21:01
-
Subtleties of witnessing quantum coherence in nonisolated systems
摘要： Identifying nonclassicality unambiguously and inexpensively is a long-standing open challenge in physics. The no-signaling-in-time protocol was developed as an experimental test for macroscopic realism, and serves as a witness of quantum coherence in isolated quantum systems by comparing the quantum state to its completely dephased counterpart. We show that it provides a lower bound on a certain resource-theoretic coherence monotone. We go on to generalize the protocol to the case where the system of interest is coupled to an environment. Depending on the manner of the generalization, the resulting witness either reports on system coherence alone, or on a disjunction of system coherence with either (i) the existence of nonclassical system-environment correlations or (ii) non-negligible dynamics in the environment. These are distinct failure modes of the Born approximation in nonisolated systems.
关键词： no-signaling-in-time protocol,macroscopic realism,quantum coherence,Born approximation,nonclassicality
更新于2025-09-10 09:29:36
-
Probing Nonclassicality of Two-Mode SU(2) Generator Based on Quantum Fisher Information
摘要： 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 di?erent behaviors in the two phases.
关键词： quantum Fisher information,coherence,nonclassicality
更新于2025-09-09 09:28:46
-
Testing nonclassicality with exact Wigner currents for an anharmonic quantum system
摘要： Phase-space features of the Wigner flow for an anharmonic quantum system driven by the harmonic oscillator potential modified by the addition of an inverse square (one-dimensional Coulomb-like) contribution are analytically described in terms of Wigner functions and Wigner currents. Reporting about three correlated continuity equations which quantify the flux of quantum information in the phase space, the nonclassicality profile of such an anharmonic system can be consistently obtained in terms of the fluxes of probability, purity, and von Neumann–like entropy. Considering that quantum fluctuations can be identified from distortions over the classical regime, they can be quantified through the above-mentioned information fluxes whenever some classically bounded volume of the phase space is selected. Our results suggest that the Wigner flow approach works as a probe of quantumness and classicality for a large set of anharmonic quantum systems driven by quantum wells.
关键词： anharmonic quantum system,Wigner flow,quantum information,phase space,nonclassicality
更新于2025-09-09 09:28:46
-
Higher-order intermodal antibunching for couple-cavity optomechanical system
摘要： Higher-order intermodal antibunching for couple-cavity optomechanical system is investigated by solving Heisenberg’s equations of motion analytically for various field modes using short-time dynamics under strong coupling regime neglecting the effect of dissipation and environmental effects. Temporal variation of this nonclassical effect is also studied for different values of coupling strength and photon-hopping interaction term. The degree of nonclassicality increases as order grows.
关键词： Higher-order nonclassicality,Antibunching,Optomechanics
更新于2025-09-09 09:28:46
-
Time ordering in the classically driven nonlinear Jaynes-Cummings model
摘要： Recently [F. Krumm and W. Vogel, Phys. Rev. A 97, 043806 (2018)], the detuned and nonlinear Jaynes-Cummings model describing the quantized motion of a trapped ion was introduced and its corresponding dynamics was solved via considering the driving laser in a quantized manner. For the dynamics with a classical driving laser an approximation in terms of neglected time ordering was considered to obtain analytical expressions and compared to numerically obtained exact dynamics, which revealed the insufficiency of this approximation. In the present work we reconsider this model and show that it can likewise be solved analytically, i.e., including time ordering, with a classical driving laser field. Using the analytical solution, we investigate the quantum time-ordering effects of the system with respect to nonclassicality and nonsimulatability of the motional states of the ion. Furthermore, we use the Magnus expansion to analyze the impact of certain orders of the time ordering. We derive an exact radius of convergence for these time-ordering corrections beyond the established and only sufficient criterion. Finally, the differences between the solution derived here and the previously found one using a quantized pump are discussed.
关键词： trapped ion,Jaynes-Cummings model,quantized motion,time ordering,nonsimulatability,nonclassicality,Magnus expansion
更新于2025-09-04 15:30:14