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Quantum correlation interferometry in reflection: Application to the quantum–classical transition, decoherence, and indirect measurement
摘要： A many-body interferometer is described in which all of its components are treated as quantum objects. It consists of particles reflecting elastically from a “mirror.” Quantum correlation is a consequence of conservation of energy and momentum while interference occurs when the order in which the non-local particles reflect is indeterminate. The resulting superposition exhibits correlated interference with diverse characteristics depending on the structure of the many-body wave group. Two non-local microscopic particles reflecting from a mesoscopic “mirror” illustrate unique features of this correlation interferometer. The microscopic momentum exchanged then results in small displacements of the superposed mesoscopic mirror substates, which mitigates experimental difficulties in determining the quantum-classical boundary. Quantum behavior of this mesoscopic mirror, evident in indirect measurements involving correlations between only the reflecting microscopic particles, disappears for a classical mirror which cannot exist in such superposition states.
关键词： interferometry,indirect measurement,decoherence,quantum-classical transition,quantum correlation
更新于2025-09-23 15:21:01
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Quantum correlation and squeezing dynamics of a dissipative nonlinear optomechanical oscillator: Heisenberg-Langevin approach
摘要： In this paper, an optomechanical cavity that is quadratically coupled to the cavity ?eld and formed by a micropillar with Bragg re?ectors and a thin dielectric membrane, is studied. In addition, it is considered that this interaction occurs in the presence of Kerr medium, external laser ?eld and damping e?ects (for cavity ?eld and moving Bragg re?ector). Using the Heisenberg-Langevin approach, the dynamics of quantum correlation functions (for cavity ?eld and moveable re?ector) and squeezing parameters for quadratures of the cavity ?eld are investigated. In each case, the in?uences of optomechanical coupling, detuning parameter, thermal mean number of cavity photons and phonons, damping parameters and Kerr medium on the above nonclassicality features are analyzed in detail. It is illustrated that the amount of the above-mentioned physical phenomena can be controlled by appropriately choosing the evolved parameters. Also, we show that photon and phonon blockades emerge in some special cases.
关键词： squeezing dynamics,quantum correlation,photon blockade,optomechanical cavity,Kerr medium,Heisenberg-Langevin approach,phonon blockade
更新于2025-09-23 15:21:01
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Second-order correlation function of fluorescence from a few atoms near plasmonic surface
摘要： We have used a full quantum mechanical approach to study the second-order correlation function of a system of a few two-level atoms coupled via plasmons. By the usage of quantum regression theory we have developed a new model that allows us to fully investigate the dependence of photon bunching and anti-bunching effects to the interaction between atoms, fields and surrounding medium. Using Dicke basis for several atomic systems, we show that Dicke states can be coupled via various relaxation processes near plasmonic and metamaterial surfaces, and as a result, the second-order correlation function has various characteristic time scales related to the supperadiant and subradiant transitions and these prediction can be observed experimentally.
关键词： quantum coherence,nanoparticle,quantum correlation,G2
更新于2025-09-19 17:13:59
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Wigner Representation for Investigation of Entangled Photon Evolution in Four-Wave Mixing Process within a Fiber Ring Resonator
摘要： The aim of this study is to analyze the quantum correlation of entangled photons for four-wave mixing process within Kerr nonlinear susceptibility χ(3) of an optical fiber ring resonator. The main system Hamiltonian composes of two types of coupling photon modes, including pumping and parametric-down conversion. Wigner representation is applied to the Heisenberg equation of motion derived from the system Hamiltonian in order to obtain the corresponding stochastic equations of motion in a c-number. Quantum trajectories obtained from the stochastic equation of motion of photon states are then derived. Finally, the entanglement inseparability criteria for a pair of entangled photon from a numerical approach is also satisfied.
关键词： Four-Wave Mixing,Quantum Correlation,Entangled Photons
更新于2025-09-16 10:30:52
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Experimental test of error-tradeoff uncertainty relation using a continuous-variable entangled state
摘要： Heisenberg’s original uncertainty relation is related to measurement effect, which is different from the preparation uncertainty relation. However, it has been shown that Heisenberg’s error disturbance uncertainty relation is not valid in some cases. We experimentally test the error-tradeoff uncertainty relation by using a continuous-variable Gaussian Einstein–Podolsky–Rosen (EPR)-entangled state. Based on the quantum correlation between the two entangled optical beams, the errors on amplitude and phase quadratures of one EPR optical beam coming from joint measurement are estimated, respectively, which are used to verify the error–tradeoff relation. Especially, the error–tradeoff relation for error-free measurement of one observable is veri?ed in our experiment. We also verify the error–tradeoff relations for nonzero errors and mixed state by introducing loss on one EPR beam. Our experimental results demonstrate that Heisenberg’s error–tradeoff relation is violated in some cases for a continuous-variable system, while the Ozawa’s and Branciard’s relations are valid.
关键词： continuous-variable Gaussian Einstein–Podolsky–Rosen (EPR)-entangled state,error-tradeoff uncertainty relation,quantum correlation,Heisenberg’s uncertainty relation,joint measurement
更新于2025-09-11 14:15:04
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Witnessing bipartite entanglement sequentially by multiple observers
摘要： We investigate sharing of bipartite entanglement in a scenario where half of an entangled pair is possessed and projectively measured by one observer, called Alice, while the other half is subjected to measurements performed sequentially, independently, and unsharply, by multiple observers, called Bobs. We ?nd that there is a limit on the number of observers in this entanglement distribution scenario. In particular, for a two-qubit maximally entangled initial shared state, no more than 12 Bobs can detect entanglement with a single Alice for arbitrary, possibly unequal, sharpness parameters of the measurements by the Bobs. The number of Bobs remains unaltered for a ?nite range of near-maximal pure initial entanglement, a feature that also occurs in the case of equal sharpness parameters at the Bobs. Furthermore, we show that for nonmaximally entangled shared pure states, the number of Bobs decreases with the amount of initial entanglement, providing a coarse-grained but operational measure of entanglement.
关键词： sequential measurements,entanglement,unsharp measurements,entanglement witnesses,quantum correlation
更新于2025-09-09 09:28:46
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Quantum imaging with sub-Poissonian light: challenges and perspectives in optical metrology
摘要： Non-classical correlations in optical beams offer the unprecedented opportunity of surpassing conventional limits of sensitivity and resolution in optical measurements and imaging, especially but not only, when a low photon flux down/single photons are measured. We review the principles of quantum imaging and sensing techniques which exploit sub-Poissonian photon statistics and non-classical photon number correlation, presenting some state-of-the-art achievements in the field. These quantum photonics protocols have the potential to trigger major steps in many applications, such as microscopy and biophotonics and represent an important opportunity for a new deal in radiometry and photometry.
关键词： quantum optics,quantum correlation,sub-Poissonian light,Quantum enhanced measurement
更新于2025-09-04 15:30:14