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Physical Review A (24699934) 109(5)
Accurate temperature measurement is critical in many scientific and engineering fields, so that researchers continuously strive to improve the accuracy, sensitivity, and robustness of the current measurement methods. In this paper, we propose a theoretical approach for temperature measurement using an optomechanical system in which the position of a mechanical oscillator is coupled to the cavity field. Our approach enables precise control and manipulation of both, resulting in highly accurate temperature measurements. We evaluate the accuracy of temperature estimation by using classical and quantum Fisher information, considering both open and closed systems, and investigate entanglement effects of the primary field mode. Our findings indicate that increasing entanglement at the input made reduces measurement time and increases sensitivity in estimating the temperature. However, we observe that quantum coherence is destroyed by decoherence, leading to reduced performance of quantum systems. Furthermore, we show that the Fisher information of the system is robust against mechanical decoherence, but significantly damped due to optical decoherence. We discuss the limitations and challenges of our method and suggest possible applications and future directions for our research. Finally, we determine the accuracy of temperature estimation for a typical optomechanical system based on phase values measured in the closed system. Our results demonstrate the potential of optomechanical systems for highly accurate temperature measurement and their robustness against decoherence. This study can provide insights into the field of temperature measurement, offering a theoretical approach that can be applied in many scientific and engineering applications. © 2024 American Physical Society.
Journal of the Optical Society of America B: Optical Physics (07403224) 39(5)pp. 1353-1363
In this paper, to study the effects of a nonlinear medium on the atom-field interaction, we use the nonlinear coherent states approach. For this purpose, we choose the two-mode cross-Kerr as our nonlinear optical phenomena, and with the use of its algebra, we show that it can be considered as a deformed oscillator as well as a deformed su(2) algebra. Then we construct the associated two-mode nonlinear coherent states and investigate their statistical properties. After that, as an example of applicability of the constructed coherent states, we investigate the nonlinear effects of the medium on the dynamics of atom-field interaction within the framework of the coherent states. By using the time-dependent Schrödinger equation, we study the effect of the nonlinear medium on the occupation probabilities of the atomic levels and consider the relation between the revival time of the atomic occupation probabilities and the nonlinear parameter of the medium. Then, to study the nonlinear effects on the dynamical properties of the cavity field, we consider the photon distribution, correlation function, Mandel parameters of the field, von Neumann entropy, and also the squeezing. Particularly, the nonlinearity of the media on the nonclassical properties of the two modes is clarified. © 2022 Optica Publishing Group
Journal of Optics (United Kingdom) (20408986) 21(1)
Quantum surface plasmon polaritons (SPPs) are a growing research area with many unknown phenomena. In this paper, the behavior of squeezed SPP modes on a metal slab is assessed. To begin with, a quantized form of the SPP modes propagating on the metal thin film based on Green's tensor method is provided. Since the squeezing properties of the SPP modes are indeed transferred from incident photons, in the next step, different aspects of this phenomenon are studied. Obtaining an important direct relation between incident photons' properties and SPP modes will allow for the effective factors on this phenomenon to be explored. Although the initial quantum properties will be changed or lost during the photon-surface plasmon interaction, it will be shown that some factors can improve the transfer process. Finally, the squeezing transfer from incident photons to the SPP modes and effective factors on it as a full quantum phenomenon will be investigated. © 2018 IOP Publishing Ltd.
Physical Review A (24699934) 99(6)
The field of optomechanics provides us with several examples of quantum photon-phonon interface. In this paper, we theoretically investigate the generation and manipulation of quantum correlations in a microfabricated optomechanical array. We consider a system consisting of localized photonic and phononic modes interacting locally via radiation pressure at each lattice site with the possibility of hopping of photons and phonons between neighboring sites. We show that such an interaction can correlate various modes of a driven coupled optomechanical array with well-chosen system parameters. Moreover, in the linearized regime of Gaussian fluctuations, the quantum correlations not only survive in the presence of thermal noise, but may also be generated thermally. We find that these optomechanical arrays provide a suitable platform for quantum simulation of various many-body systems. © 2019 American Physical Society.
Annals of Physics (00034916) 405pp. 202-219
We consider an optomechanical cavity with a movable end-mirror as a quantum mechanical oscillator (MO) containing an interacting cigar-shaped Bose–Eisenstein condensate (BEC). It is assumed that both the MO and the BEC interact with the radiation pressure of the cavity field in the red-detuned and weak coupling regimes while the two-body atomic collisions frequency of the BEC and the mechanical spring coefficient of the MO are coherently modulated. By analyzing the scattering matrix, we show that in the largely different cooperativities regime together with strong modulations, the mechanical mode of the MO and the Bogoliubov mode of the BEC exhibit quadrature squeezing which can surpass the so-called 3dB limit (up to 75 dB) with high robustness to the thermal noises. Surprisingly, in this regime by controlling the system and modulation parameters, a very high degree of squeezing (up to 16 dB) together with high purity of quantum state for the output cavity field is achievable. Furthermore, one can attain simultaneous strong quantum amplification, added-noise suppression, and controllable gain-bandwidth for the complementary quadratures of squeezed ones in the subsystems. © 2019 Elsevier Inc.
Annals of Physics (00034916) 396pp. 202-219
We theoretically propose and investigate a feasible experimental scheme for the realization of the dynamical Casimir effect (DCE) in a hybrid optomechanical cavity with a moving end mirror containing an interacting cigar-shaped Bose–Einstein condensate (BEC). We show that in the red-detuned regime of cavity optomechanics together with the weak optomechanical coupling limit by coherent modulation of the s-wave scattering frequency of the BEC and the mechanical spring coefficient of the mechanical oscillator (MO), the mechanical and atomic quantum vacuum fluctuations are parametrically amplified, which consequently lead to the generation of the mechanical/Bogoliubov-type Casimir phonons. Interestingly, in the coherent regime corresponding to the case of largely different optomechanical coupling strengths of the cavity field to the BEC and the MO, or equivalently largely different cooperativities, one can generate a large number of Casimir photons due to the amplification of the intracavity vacuum fluctuations induced by the time modulations of the BEC and the MO. The number of generated Casimir particles are externally controllable by the cooperativities, and the modulation amplitudes of the atomic collisions rate and the mechanical spring coefficient. © 2018 Elsevier Inc.
Annals of Physics (00034916) 388pp. 186-196
We present a theoretical scheme to simulate quantum field theory in a discrete curved spacetime based on the Bose–Hubbard model describing a Bose–Einstein condensate trapped inside an optical lattice. Using the Bose–Hubbard Hamiltonian, we first introduce a hydrodynamic presentation of the system evolution in discrete space. We then show that the phase (density) fluctuations of the trapped bosons inside an optical lattice in the superfluid (Mott insulator) state obey the Klein–Gordon equation for a massless scalar field propagating in a discrete curved spacetime. We derive the effective metrics associated with the superfluid and Mott-insulator phases and, in particular, we find that in the superfluid phase the metric exhibits a singularity which can be considered as the manifestation of an analog acoustic black hole. The proposed approach is found to provide a suitable platform for quantum simulation of various spacetime metrics through adjusting the system parameters. © 2017
Journal of the Optical Society of America B: Optical Physics (07403224) 34(12)pp. 2519-2527
In this paper, we theoretically propose an optomechanical scheme to explore the possibility of simulating the propagation of the collective excitations of the photon fluid in a curved spacetime. For this purpose, we introduce two theoretical models for two-dimensional photon gas in a planar optomechanical microcavity and a two-dimensional array of coupled optomechanical systems. In the reversed dissipation regime of cavity optomechanics where the mechanical oscillator reaches equilibrium with its thermal reservoir much faster than the cavity modes, the mechanical degrees of freedom can adiabatically be eliminated. The adiabatic elimination of the mechanical mode provides an effective nonlinear Kerr-type photon–photon interaction. Using the nonlinear Schrödinger equation, we show that the phase fluctuations in the two-dimensional photon fluid obey the Klein–Gordon equation for a massless scalar field propagating in a curved spacetime. The results reveal that the photon fluid as well as the corresponding metric can be controlled by manipulating the system parameters. © 2017 Optical Society of America.
Journal of the Optical Society of America B: Optical Physics (07403224) 34(3)pp. 642-652
In this paper, we theoretically propose and investigate a feasible experimental scheme to realize the dynamical Casimir effect (DCE) of phonons in an optomechanical setup formed by a ground-state precooled mechanical oscillator (MO) inside a Fabry-Perot cavity, which is driven by an amplitude-modulated classical laser field in the dispersive (far-detuned) regime. The time modulation of the driving field leads to the parametric amplification of the mechanical vacuum fluctuations of the MO, which results in the generation of Casimir phonons over time scales longer than the cavity lifetime. We show that the generated phonons exhibit quadrature squeezing, bunching effect, and super-Poissonian statistics, which are controllable by the externally modulated laser pump. In particular, we find that the scheme enables a perfect squeezing transfer from one mechanical quadrature to another when the laser frequency is varied from red detuning to blue detuning. Moreover, by analyzing the effect of the thermal noise of the MO environment, we find that there exists a critical temperature above which no phonon quadrature squeezing occurs. We also show that in the presence of time modulation of the driving laser, the linewidth narrowing of the displacement spectrum of the MO can be considered a signature of the generation of Casimir phonons. © 2017 Optical Society of America.
Physical Review A (24699934) 96(2)
Spontaneous synchronization is a significant collective behavior of weakly coupled systems. Due to their inherent nonlinear nature, optomechanical systems can exhibit self-sustained oscillations which can be exploited for synchronizing different mechanical resonators. In this paper, we explore the synchronization dynamics of two membranes coupled to a common optical field within a cavity, and pumped with a strong blue-detuned laser drive. We focus on the system quantum dynamics in the parameter regime corresponding to synchronization of the classical motion of the two membranes. With an appropriate definition of the phase difference operator for the resonators, we study synchronization in the quantum case through the covariance matrix formalism. We find that for sufficiently large driving, quantum synchronization is robust with respect to quantum fluctuations and to thermal noise up to not too large temperatures. Under synchronization, the two membranes are never entangled, while quantum discord behaves similarly to quantum synchronization, that is, it is larger when the variance of the phase difference is smaller. © 2017 American Physical Society.
International Journal of Theoretical Physics (15729575) 55(1)pp. 124-136
In this paper, we study the quantum free particle on the spherical space by applying da costa approach for quantum particle on the curved space. We obtain the discrete energy eigenvalues and associated normalized eigenfunctions of the free particle on the sphere. In addition, we introduce the Gazeau-Klauder coherent states of free particle on the sphere. Then, the Gaussian coherent states is defined, which is used to describe the localized particle on the spherical space. Finally, we study the relation between the f-deformed coherent states and Gazeau-Klauder ones for this system. © 2015, Springer Science+Business Media New York.
Progress in Electromagnetics Research M (19378726) 49pp. 117-129
An optical impedance-matched medium with a gradient refractive index can resemble a geometrical analogy with an arbitrary curved space-time. In this paper, we show that a non-impedancematched medium with a varying optical axis can also resemble the features of a space of non-trivial metric for the light. The medium with a varying optical axis is an engineered stratified slab of material, in which the orientation of the optical axis in each layer slightly differs from the other layers, while the magnitude of refractive index remains constant. Instead of the change in refractive index, the inhomogeneity of such a medium is induced by the local anisotropy. Therefore, the propagation of light depends on the local optical axis. We study the conditions that make the analogy between curved spacetime and a medium with a varying optical axis. Extension of the transformation optics to the media with optical axis profile might ease some fabrication difficulties of materials with gradient refractive index. © 2016, Electromagnetics Academy. All rights reserved.
Molecular Physics (00268976) 114(14)pp. 2123-2131
ABSTRACT: The dynamics of energy transfer in Fenna–Matthews–Olson (FMO) light-harvesting complex interacting with a phonon bath is investigated. In this contribution, by considering the phonon bath as a source of stochastic noise, a new approach is proposed. Also, by calculating the global quantum entanglement and global quantum discord, the time evolution of the quantum correlation during the process is evaluated. The effects of temperature and initial excited state on the energy transfer and the quantum correlation are studied. It is shown, in agreement with the previous results, that the increasing of the temperature gives rise to the faster delocalisation of energy transfer and global quantum entanglement in the FMO complex. The proposed model predicts that the global discord is resistance versus the raising temperature. Furthermore, it is demonstrated that the quantum entanglement with respect to the global quantum discord has a significant role in the process of energy transfer in the FMO complex. © 2016 Informa UK Limited, trading as Taylor & Francis Group.
New Journal Of Physics (13672630) 18(7)
We propose and analyse a feasible experimental scheme for a quantum force sensor based on the elimination of backaction noise through coherent quantum noise cancellation (CQNC) in a hybrid atom-cavity optomechanical setup assisted with squeezed vacuum injection. The force detector, which allows for a continuous, broadband detection of weak forces well below the standard quantum limit (SQL), is formed by a single optical cavity simultaneously coupled to a mechanical oscillator and to an ensemble of ultracold atoms. The latter acts as a negative-mass oscillator so that atomic noise exactly cancels the backaction noise from the mechanical oscillator due to destructive quantum interference. Squeezed vacuum injection enforces this cancellation and allows sub-SQL sensitivity to be reached in a very wide frequency band, and at much lower input laser powers. © 2016 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Journal of Optics (United Kingdom) (20408986) 18(11)
In non-magnetic anisotropic media, the behavior of electromagnetic waves depends on the polarization and direction of the incident light. Therefore, to tame the unwanted wave responses such as polarization dependent reflections, the artificial impedance-matched media are suggested to be used in optical devices like invisibility cloak or super lenses. Nevertheless, developing the impedance-matched media is far from trivial in practice. In this paper, we are comparing the samples of both impedance-matched and non-impedance-matched (non-magnetic) media regarding their electromagnetic response in constructing a well-defined optical metric. In the case of similar anisotropic patterns, we show that the optical metric in an impedance-matched medium for unpolarized light is the same as the optical metric of an electrical birefringent medium when the extraordinary mode is concerned. By comparing the eikonal equation in an empty curved space-time and its counterparts in the medium, we have shown that a non-impedance-matched medium can resemble an optical metric for a particular polarization. As an example of non-impedance-matched materials, we are studying a medium with varying optical axis profile. We show that such a medium can be an alternative to impedance-matched materials in various optical devices. © 2016 IOP Publishing Ltd.
Journal of Physics B: Atomic, Molecular and Optical Physics (09534075) 49(18)
The dynamics of single-excitation energy transfer in a molecular dimer interacting with a phonon bath is studied. Although there are exact numerical solutions for this system, we propose an approach that provides exact analytical results with few electronic degrees of freedom. This approach is based on considering the phonon subsystem in the coherent state representation. Applying this approach, the long-lived coherence time is evaluated in the weak and strong coupling regimes. Moreover, by calculating the quantum entanglement and global quantum discord, the time evolution of quantum correlations is examined. The effects of two parameters, electronic coupling strength and bath temperature, on the energy transfer and quantum correlations are studied. It is shown, in agreement with previous results, that the long-lived coherence time in the weak coupling regime is longer than in the strong coupling regime. Also, the increasing bath temperature gives rise to faster delocalization of energy transfer. Furthermore, it is illustrated that the bath temperature has a significant effect on the quantum entanglement with respect to the global quantum discord. © 2016 IOP Publishing Ltd.
Plasmonics (15571963) 11(3)pp. 875-884
In this paper, we will present a quantization method for surface plasmon polariton (SPP) based on Green’s tensor method, which is applied usually for quantization of EM field in various dielectric media. This method will be applied for a semi-infinite structure, which contains metal and dielectric regions with one interface. Moreover, by introducing the quantized SPP, we will investigate the SPP propagation in the attenuating and amplifying systems. We will also consider two modes of SPP, i.e., coherent and squeezed states, and finally compare the propagation of these modes in the amplifying media. © 2015, Springer Science+Business Media New York.
Physical Review A (24699934) 93(5)
In this paper, we theoretically investigate the displacement and momentum fluctuations spectra of the movable mirror in a standard optomechanical system driven by a finite-bandwidth squeezed vacuum light accompanying a coherent laser field. Two cases in which the squeezed vacuum is generated by degenerate and nondegenerate parametric oscillators (DPO and NDPO) are considered. We find that for the case of finite-bandwidth squeezed vacuum injection, the two spectra exhibit unique features, which strongly differ from those of broadband squeezing excitation. In particular, the spectra exhibit a three-peaked and a four-peaked structure, respectively, for the squeezing injection from DPO and NDPO. Besides, some anomalous characteristics of the spectra such as squeezing-induced pimple, hole burning, and dispersive profile are found to be highly sensitive to the squeezing parameters and the temperature of the mirror. We also evaluate the mean-square fluctuations in position and momentum quadratures of the movable mirror and analyze the influence of the squeezing parameters of the input field on the mechanical squeezing. It will be shown that the parameters of driven squeezed vacuum affects the squeezing. We find the optimal mechanical squeezing is achievable via finite-bandwidth squeezed vacuum injection which is affected by the intensity of squeezed vacuum. We also show that the phase of incident squeezed vacuum determines whether position or momentum squeezing occurs. Our proposed scheme not only provides a feasible experimental method to detect and characterize squeezed light by optomechanical systems, but also suggests a way for controllable transfer of squeezing from an optical field to a mechanical oscillator. © 2016 American Physical Society.
Journal of Physics B: Atomic, Molecular and Optical Physics (09534075) 49(6)
Using two different schemes, a non-classical-squeezed state of light is detected and characterized. In the first scheme, in a one-dimensional cavity with a moving mirror (non-stationary Casimir effect) in the principal mode, we study the photon generation rate for two modes (squeezed and coherent state) of a driving field. Since the cavity with the moving mirror (similar to an optomechanical system) can be considered an analogue to a Kerr-like medium, in the second scheme, the probability amplitude for multi-photon absorption in a nonlinear (Kerr) medium will be quantum mechanically calculated. It is shown that because of the presence of nonlinear effects, the responses of these two systems to the squeezed versus coherent state are considerably distinguishable. The drastic difference between the results of these two states of light can be viewed as a proposal for detecting non-classical states. © 2016 IOP Publishing Ltd.
Journal of the Optical Society of America B: Optical Physics (07403224) 32(8)pp. 1555-1563
We present and investigate an analogue model for controllable photon generation via the dynamical Casimir effect (DCE) in a cavity containing a degenerate optical parametric amplifier (OPA), which is pumped by an amplitude-modulated field. The time modulation of the pump field in the model OPA system is equivalent to a periodic modulation of the cavity length, which is responsible for the generation of the Casimir radiation. By taking into account the rapidly oscillating terms of the modulation frequency, the effects of the corresponding counter-rotating terms (CRTs) on the analogue Casimir radiation clearly emerge. We find that the mean number of generated photons and their quantum statistical properties exhibit oscillatory behaviors, which are controllable through the modulation frequency as an external control parameter. We also find that the time-modulated pumping may lead to the recently predicted phenomenon, the so-called "anti-DCE," in which pair photons can be coherently annihilated. We show that the Casimir radiation exhibits quadrature squeezing, photon bunching, and super-Poissonian statistics, which are controllable by modulation frequency. We also calculate the power spectrum of the intracavity light field. We find that the appearance of sidebands in the spectrum is due to the presence of the CRTs. © 2015 Optical Society of America.
Foundations of Physics (15729516) 45(7)pp. 827-839
In this work we present a construction of coherent states based on ”complexifier” method for a special type of one dimensional nonlinear harmonic oscillator presented by Mathews and Lakshmanan (Q Appl Math 32:215, 1974). We will show the state quantization by using coherent states, or to build the Hilbert space according to a classical phase space, is equivalent to departure from real coordinates to complex ones. © 2015, Springer Science+Business Media New York.
Quantum Information Processing (15700755) 14(8)pp. 2895-2907
In this paper, we investigate the behavior of radiation field, whose state is described by the so-called sphere coherent state, through a beam splitter. These states are realization of coherent states of two-dimensional harmonic oscillator, which lives on a sphere, as radiation field. By using the linear entropy as a measure of entanglement, we show that the entanglement depends on the curvature of the sphere. So, by using the appropriating sphere coherent states, we can control the entanglement of the output states of the beam splitter in the laboratory. In addition, as the convince measures of non-classical behaviors, we consider Mandel parameters of the output states of the beam splitter and their quadrature squeezing. © 2015, Springer Science+Business Media New York.
Quantum Information Processing (15700755) 14(2)pp. 593-606
In this paper, we suggest a scheme which can produce various types of entangled states of the cavity field. In the scheme, cavities with different circumstances which evolve in time are utilized. It is shown that if two cavities are arranged in a way that, the first cavity is governed by the Jaynes–Cummings (JC) and the other with anti-Jaynes–Cummings (anti-JC) Hamiltonian, entangled EPR state of the cavity field is generated. Also, the proposal can be extended to the multi-cavity case, where the cavities are arranged such that their time evolutions change alternately from JC to anti-JC Hamiltonian. From this configuration, three- and four-partite GHZ states can be generated. At last, it is illustrated that in the multi-cavity set up if one prepares all cavities with the same time evolution property, W state can be produced. An important feature of this scheme is the fact that the result of the processes is independent of the result of atomic detection. © 2014, Springer Science+Business Media New York.
Journal of the Optical Society of America B: Optical Physics (07403224) 32(7)pp. 1360-1368
A theoretical scheme for the realization of the sphere-coherent motional states in an optomechanical cavity in the presence of a two-level atom is proposed. To this end, the analogy between an atom-assisted optomechanical cavity and a laser-driven trapped-ion system is used. This analogy provides us with a theoretical tool to show how sphere-coherent states (SCSs) can be generated for the motional degree of freedom of the macroscopic mechanical oscillator (MO) from atom-field-mirror interactions in a multimode optomechanical cavity. Some nonclassical properties of the generated state of the MO, including the degree of quadrature squeezing and the negativity of the Wigner distribution, are studied. We also examine the effects of the dissipation mechanisms involved in the system under consideration, including the atomic spontaneous emission and the damping of the motion of the MO, on the generated motional SCSs. © 2015 Optical Society of America.
Laser Physics (1054660X) 24(5)
We study the dynamics of a catlike superposition of f-deformed coherent states under dissipative decoherence. For this purpose, we investigate two important categories of f-deformed coherent states: Gazeau-Klauder and displacement-type coherent states. In addition, we consider two deformation functions; one of them describes a harmonic oscillator in an infinite well and another corresponds to a harmonic oscillator in a quantum well with finite depth. The decoherence effects appeared through a dissipative interaction of the environment with the catlike states. In this study, we first show that the Gazeau-Klauder coherent state is more resistant under the decoherence process, in contrast to the displacement-type one, and second, that the potential range of the infinite well and the depth of potential possess a remarkable role in the decoherence process. © 2014 Astro Ltd.
Modern Physics Letters A (02177323) 29(19)
We study the two-dimensional harmonic oscillator on a noncommutative plane. We show that by introducing appropriate Bopp shifts, one can obtain the Hamiltonian of a two-dimensional harmonic oscillator on a sphere according to the Higgs model. By calculating the commutation relations, we show that this noncommutativity is strictly dependent on the curvature of the background space. In other words, we introduce a kind of duality between noncommutativity and curvature by introducing noncommutativity parameters as functions of curvature. Also, it is shown that the physical realization of such model is a charged harmonic oscillator in the presence of electromagnetic field. © 2014 World Scientific Publishing Company.
Journal of the Optical Society of America B: Optical Physics (07403224) 31(2)pp. 270-276
The proposed schemes in this paper involve the interaction of a two-level atom with single- or two-mode quantized cavity fields (for different purposes) in the presence of a classical field. Indeed, following the path of Solano et al. in [Phys. Rev. Lett. 90, 027903 (2003)], the behavior of the entire atom-field system may be described by the Jaynes-Cummings (JC)- and anti-Jaynes-Cummings (anti-JC)-like models. It is illustrated that, under specific conditions, the effective Hamiltonian of the system can be switched from a JC- to an anti-JC-like model. During the process, the two-level atom in the cavity is alternately affected by the above two effective interactions. Ultimately, after the occurrence of the desired interactions in appropriate setups, the cavity field will arrive at a specific superposition of number states, a fixed number state, and in particular, two-mode binomial field states. Moreover, the entanglement property of the two-mode binomial state is investigated by evaluating the entropy criterion. While there exist various proposals for preparation of number states and their superpositions in the literature, our scheme has the advantage that it is independent of the detection of the atomic state after the interaction occurs. © 2014 Optical Society of America.
Journal of Modern Optics (13623044) 60(3)pp. 233-239
In this paper, to obtain an analogy between the curved spaces and the linear optics, we expand the idea of Sánchez-Soto and co-workers [Phys. Rep. 2012, 513, 191; Phys. Rev. A 2011, 84, 023830] to the multilayer films. We investigate effects of thickness and index of refraction of the films on the Lorentzian transformations. In addition, by using the multilayer films, we suggest a very simple experimental set-up which can serve as an analogue computer for testing special relativity. Finally, we draw an analogy between the Rindler space, as an example of the curved spaces, and a suitable multilayer film. Copyright © 2013 Taylor & Francis.
International Journal of Geometric Methods in Modern Physics (17936977) 10(5)
At first, we introduce -deformed algebra as a kind of generalization of the Weyl-Heisenberg algebra so that we get the su(2)-and su(1, 1)-algebras whenever has specific values. After that, we construct coherent states of this algebra. Third, a realization of this algebra is given in the system of a harmonic oscillator confined at the center of a potential well. Then, we introduce two-boson realization of the -deformed Weyl-Heisenberg algebra and use this representation to write -deformed coherent states in terms of the two modes number states. Following these points, we consider mean number of excitations (we call them in general photons) and Mandel parameter as statistical properties of the -deformed coherent states. Finally, the Fubini-Study metric is calculated for the -coherent states manifold. © 2013 World Scientific Publishing Company.
International Journal of Geometric Methods in Modern Physics (17936977) 10(10)
Three methods: complexifier, factorization and deformation, for construction of coherent states are presented for one-dimensional nonlinear harmonic oscillator (1D NLHO). Since by exploring the Jacobi polynomials P na,b,s, bridging the difference between them is possible, we give here also the exact solution of Schrödinger equation of 1D NLHO in terms of Jacobi polynomials. © World Scientific Publishing Company.
Annals of Physics (00034916) 334pp. 321-333
The decoherence rate and some parameters affecting it are investigated for the generalized spin-boson model. We consider the spin-bosonic model when the bosonic environment is modeled by the deformed harmonic oscillators. We show that the state of the environment approaches a non-linear coherent state. Then, we obtain the decoherence rate of a two-level system which is in contact with a deformed bosonic environment which is either in thermal equilibrium or in the ground state. By using some recent realization of f-deformed oscillators, we show that some physical parameters strongly affect the decoherence rate of a two-level system. © 2013 Elsevier Inc.
Journal of Modern Optics (13623044) 59(6)pp. 533-543
In this paper by using the coherent state path integral field theory approach, we calculate the grand canonical partition function of an interacting combined system in the presence of the relevant source terms. It allows us to calculate multi-time correlation functions of interacting systems without using the quantum regression theorem. Then, we investigate the power spectrum and the second-order correlation function of the emitted photons from a microcavity in the presence of excitations of a semiconductor quantum well. By using the Hubbard-Stratonovich transformation, we investigate the effects of reservoir, detuning, the Coulomb interaction and the phase space filling on the power spectrum and the second-order correlation function of the emitted photons. © 2012 Copyright Taylor and Francis Group, LLC.
AIP Conference Proceedings (0094243X) 1508pp. 474-477
Generalized f-coherent state approach in deformation quantization framework is investigated by using a *-eigenvalue equation. For this purpose we introduce a new Moyal star product called f-star product, so that by using this *f-eigenvalue equation one can obtain exactly the spectrum of a general Hamiltonian of a deformed system. © 2012 American Institute of Physics.
International Journal of Geometric Methods in Modern Physics (17936977) 9(1)
In this paper, by using the nonlinear coherent states approach, we find a relation between the geometric structure of the physical space and the geometry of the corresponding projective Hilbert space. To illustrate the approach, we explore the quantum transition probability and the geometric phase in the curved space. © 2012 World Scientific Publishing Company.
International Journal of Modern Physics A (0217751X) 27(18)
Generalized (f)-coherent state approach in deformation quantization framework is investigated by using a *-eigenvalue equation. For this purpose we introduce a new Moyal star product called f-star product, so that by using this * f-eigenvalue equation one can obtain exactly the spectrum of a general Hamiltonian of a deformed system. Eventually the method is supported with some examples. © 2012 World Scientific Publishing Company.
Physical Review A - Atomic, Molecular, and Optical Physics (10502947) 86(6)
We investigate a quantum-dot-based cavity system via the master-equation approach. The dynamics of the system is greatly affected by dissipation and dephasing processes. We include these phenomena to the theory through the master equation. The dissipation effects such as cavity loss, spontaneous recombination of excitons, and incoherent pumping are considered. The dephasing process is included as an electron-acoustic-phonon interaction. An intrinsic feature of solid-state cavity systems is the presence of electron-phonon interaction, which distinguishes this system from atomic cavity quantum electrodynamics. Due to the temperature dependence of phonons we use the complete form of the master equation (temperature dependence of dissipation rates) in this paper. We study the emission spectrum and photon statistics of the system. We show that cavity mode emission depends on temperature, and temperature strongly affects the photon statistics. © 2012 American Physical Society.
Journal of Physics A: Mathematical and Theoretical (17518113) 45(46)
In this paper, we investigate a two-dimensional isotropic harmonic oscillator on a time-dependent spherical background. The effect of the background can be represented as a minimally coupled field to the oscillator's Hamiltonian. For a fluctuating background, transition probabilities per unit time are obtained. Transitions are possible if the energy eigenvalues of the oscillator E i and frequencies of the fluctuating background ω n satisfy the following two simple relations: E j≃E i ω n (stimulated emission) and E j≃E i + h d ω n (absorption). This indicates that a background fluctuating at a frequency of ω n interacts with the oscillator as a quantum field of the same frequency. We believe this result is also applicable for an arbitrary quantum system defined on a fluctuating maximally symmetric background. © 2012 IOP Publishing Ltd.
Physica A: Statistical Mechanics and its Applications (03784371) 390(7)pp. 1381-1392
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 GazeauKlauder coherent states approach, the time evolution of some of the nonclassical properties of the coherent states corresponding to the considered physical systems are discussed. © 2010 Elsevier B.V. All rights reserved.
Journal of Physics A: Mathematical and Theoretical (17518113) 44(8)
Based on the definition of coherent states for continuous spectra and analogous to photon-added coherent states for discrete spectra, we introduce the excited coherent states for continuous spectra. It is shown that the main axioms of Gazeau-Klauder coherent states will be satisfied, properly. Nonclassical properties and quantum statistics of coherent states, as well as the introduced excited coherent states, are discussed. In particular, through the study of quadrature squeezing and amplitude-squared squeezing, it will be observed that both classes of the above states can be classified in the intelligent states category. © 2011 IOP Publishing Ltd.
Carmele, A. ,
Milde, F. ,
Dachner, M. ,
Bagheri harouni, M. ,
Roknizadeh, R. ,
Richter, M. ,
Knorr, A. Physical Review B - Condensed Matter and Materials Physics (10980121) 81(19)
We theoretically study the polarization entanglement of photons generated by the biexciton cascade in a GaAs/InAs semiconductor quantum dot (QD) located in a nanocavity. A detailed analysis of the complex interplay between photon and carrier coherences and phonons which occurs during the cascade allows us to clearly identify the conditions under which entanglement is generated and destroyed. A quantum state tomography is evaluated for varying exciton fine-structure splittings. Also, by constructing an effective multiphonon Hamiltonian which couples the continuum of the QD-embedding wetting layer states to the quantum confined states, we investigate the relaxation of the biexciton and exciton states. This consistently introduces a temperature dependence to the cascade. Considering typical Stranski-Krastanov grown QDs for temperatures around 80 K the degree of entanglement starts to be affected by the dephasing of the exciton states and is ultimately lost above 100 K. © 2010 The American Physical Society.
International Journal of Modern Physics A (0217751X) 24(10)pp. 1963-1986
In this paper, by using the Wess-Zumino formalism of noncommutative differential calculus, we show that the concept of nonlinear coherent states originates from noncommutative geometry. For this purpose, we first formulate the differential calculus on a GLp, q(2) quantum plane. By using the commutation relations between coordinates and their interior derivatives, we then construct the two-parameter (p, q)-deformed quantum phase space together with the associated deformed Heisenberg commutation relations. Finally, by applying the obtained results for the quantum harmonic oscillator we construct the associated coherent states, which can be identified as nonlinear coherent states. Furthermore, we show that some of the well-known deformed (nonlinear) coherent states, such as two-parameter (p, q)-deformed coherent states, Maths-type q-deformed coherent states, Phys-type q-deformed coherent states and Quesne deformed coherent states, can be easily obtained from our treatment. © 2009 World Scientific Publishing Company.
Physical Review B - Condensed Matter and Materials Physics (10980121) 79(16)
In this paper, we investigate phonon effects on the optical properties of a spherical quantum dot. For this purpose, we consider the interaction of a spherical quantum dot with classical and quantum fields while the exciton of quantum dot interacts with a solid-state reservoir. We show that phonons strongly affect the Rabi oscillations and optical coherence on first picoseconds of dynamics. We consider the quantum statistics of emitted photons by quantum dot and we show that these photons are antibunched and obey the sub-Poissonian statistics. In addition, we examine the effects of detuning and interaction of quantum dot with the cavity mode on optical coherence of energy levels. The effects of detuning and interaction of quantum dot with cavity mode on optical coherence of energy levels are compared to the effects of its interaction with classical pulse. © 2009 The American Physical Society.
Journal of Physics B: Atomic, Molecular and Optical Physics (13616455) 42(9)
We consider excitons in a quantum dot as q-deformed systems. The interaction of some excitonic systems with one cavity mode is considered. The dynamics of the system is obtained by diagonalizing the total Hamiltonian, and the emission spectrum of a quantum dot is derived. The physical consequences of a q-deformed exciton on the emission spectrum of a quantum dot are given. It is shown that when the exciton system deviates from Bose statistics, the emission spectra will become multi-peak. With our investigation we try to find the origin of the q-deformation of the exciton. The optical response of excitons, which is affected by the nonlinear nature of q-deformed systems, up to the second order of approximation is calculated and the absorption spectrum of the system is given. © 2009 IOP Publishing Ltd.
Journal of Physics A: Mathematical and Theoretical (17518113) 42(4)
In this paper we study some basic quantum confinement effects through investigation of a deformed harmonic oscillator algebra. We show that spatial confinement effects on a quantum harmonic oscillator can be represented by a deformation function within the framework of nonlinear coherent states theory. We construct the coherent states associated with the spatially confined quantum harmonic oscillator in a one-dimensional infinite well and examine some of their quantum statistical properties, including sub-Poissonian statistics and quadrature squeezing. © 2009 IOP Publishing Ltd.
Physical Review A - Atomic, Molecular, and Optical Physics (10502947) 78(6)
The preparation of coherent states of the harmonic oscillator on a sphere is considered. Based on the nonlinear coherent states of the atomic center-of-mass motion of a trapped ion, one may control the laser-ion interaction in such a way that sphere coherent states are obtained as motional dark states of the system. The curvature can be controlled by the Rabi frequencies of the driving lasers. The nonclassical properties of the resulting quantum states are analyzed. By variation of the curvature of the sphere, the states can be tuned continuously between spin-squeezed states and motional Fock states. © 2008 The American Physical Society.
Journal of Physics B: Atomic, Molecular and Optical Physics (13616455) 41(22)
In this paper, we derive the dynamical algebra of a particle confined in an infinite spherical well using the f-deformed oscillator approach. We consider an exciton with definite angular momentum in a wide quantum dot interacting with two laser beams. We show that under the weak confinement condition, and quantization of the centre-of-mass motion of exciton, its stationary state can be considered as a special kind of nonlinear coherent states which exhibits the quadrature squeezing. © 2008 IOP Publishing Ltd.
AIP Conference Proceedings (0094243X) 956pp. 245-250
In this paper, we investigate the relation between the curvature of the physical space and the deformation function of the deformed oscillator algebra using a non-linear coherent states approach. © 2007 American Institute of Physics.
Journal of Physics A: Mathematical and General (13616447) 39(22)pp. 7003-7014
In this paper, we investigate the relation between the curvature of the physical space and the deformation function of the deformed oscillator algebra using the nonlinear coherent states approach. For this purpose, we study two-dimensional harmonic oscillators on the flat surface and on a sphere by applying the Higgs model. With the use of their algebras, we show that the two-dimensional oscillator algebra on a surface can be considered as a deformed one-dimensional oscillator algebra where the effect of the curvature of the surface appears as a deformation function. We also show that the curvature of the physical space plays the role of deformation parameter. Then we construct the associated coherent states on the flat surface and on a sphere and compare their quantum statistical properties, including quadrature squeezing and antibunching effect. © 2006 IOP Publishing Ltd.
European Physical Journal D (14346060) 32(3)pp. 397-408
In this paper we propose a theoretical scheme to show the possibility of generating various families of nonlinear (f-deformed) coherent states of the radiation field in a micromaser. We show that these states can be provided in a lossless micromaser cavity under the weak Jaynes-Cummings interaction with intensity-dependent coupling of large number of individually injected two-level atoms in a coherent superposition of the upper and lower states. In particular, we show that the so-called nonlinear squeezed vacuum and nonlinear squeezed first excited states, as well as the even and odd nonlinear coherent states can be generated in a two-photon micromaser. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2005.
Journal of Mathematical Physics (10897658) 46(4)
Using the analytic representation of the so-called Gazeau-Klauder coherent states (CSs), we shall demonstrate that how a new class of generalized CSs, namely the family of dual states associated with theses states, can be constructed through viewing these states as temporally stable nonlinear CSs. Also we find that the ladder operators, as well as the displacement type operator corresponding to these two pairs of generalized CSs, may be easily obtained using our formalism, without employing the supersymmetric quantum mechanics (SUSYQM) techniques. Then, we have applied this method to some physical systems with known spectrum, such as Pöschl-Teller, infinite well, Morse potential and hydrogenlike spectrum as some quantum mechanical systems. Finally, we propose the generalized form of the Gazeau-Klauder CS and the corresponding dual family. © 2005 American Institute of Physics.
Journal of the Physical Society of Japan (13474073) 73(9)pp. 2413-2423
Temporal evolution of atomic properties including the population inversion and quantum fluctuations of atomic dipole variables are discussed in three variants of the two-photon q-deformed Jaynes-Cummings model. The model is based on the generalized deformed oscillator algebra, [Â,Â+] = (N̂ + 1)f2(N + 1) - N̂f2(N̂) in which f(N̂) as a function of number operator N̂ determines not only the intensity dependence of atom-field coupling, when the model Hamiltonian is expressed in terms of non-deformed field operators, but also the structure of initial state of the radiation field. With the field initially being in three different types of q-deformed coherent states, each of them corresponding to a particular form of the function f(N̂), the quantum collapse and revival effects as well as atomic dipole squeezing are studied for both on- and off-resonant atom-field interaction. Particularly, it is shown that for nonzero detuning the atomic inversion exhibits superstructures, which are absent in the non-deformed Jaynes-Cummings model, and the magnitude of dipole squeezing may be increased. © 2004 The Physical Society of Japan.
Progress of Theoretical Physics (13474081) 112(5)pp. 797-809
Considering a simple generalization of the (p, q)-deformed boson oscillator algebra, which leads to a two-parameter deformed bosonic algebra in an infinite dimensional subspace of the harmonic oscillator Hilbert space without first finite Fock states, we establish a new harmonic oscillator realization of the deformed boson operators based on the Bogoliubov (p, q)-transformations. We obtain exact expressions for the transformation coefficients and show that they depend on arbitrary functions of p and q which can be interpreted as the parameters of the (p, q)-deformed GL(2, C) group. We also examine the existence and structure of the corresponding deformed Fock-space representation for our problem.
Journal of Physics A: Mathematical and General (03054470) 37(9)pp. 3225-3240
In this paper, we introduce a new family of photon-added as well as photon-depleted q-deformed coherent states related to the inverse q-boson operators. These states are constructed via the generalized inverse q-boson operator actions on a newly introduced family of q-deformed coherent states (Quesne C 2002 J. Phys. A: Math. Gen. 35 9213) which are defined by slightly modifying the maths-type q-deformed coherent states. The quantum statistical properties of these photon-added and photon-depleted states, such as quadrature squeezing and photon-counting statistics, are discussed analytically and numerically in the context of both conventional (nondeformed) and deformed quantum optics.
Canadian Journal of Physics (00084204) 82(8)pp. 623-646
By introducing a generalization of the (p, q)-deformed boson oscillator algebra, we establish a two-parameter deformed oscillator algebra in an infinite-dimensional subspace of the Hubert space of a harmonic oscillator without first finite Fock states. We construct the associated coherent states, which can be interpreted as photon-added deformed states. In addition to the mathematical characteristics, the quantum statistical properties of these states are discussed in detail analytically and numerically in the context of conventional as well as deformed quantum optics. Particularly, we find that for conventional (nondeformed) photons the states may be quadrature squeezed in both cases Q = pq < 1, Q = pq > 1 and their photon number statistics exhibits a transition from sub-Poissonian to super-Poissonian for Q < 1 whereas for Q > 1 they are always sub-Poissonian. On the other hand, for deformed photons, the states are sub-Poissonian for Q > 1 and no quadrature squeezing occurs while for Q < 1 they show super-Poissonian behavior and there is a simultaneous squeezing in both field quadratures.
Progress of Theoretical Physics (13474081) 112(5)pp. 811-829
We construct a family of deformed boson coherent states associated with deformed Bogoliubov (p, q)-transformations in an infinite dimensional subspace of the harmonic oscillator Hilbert space without first finite Fock states. We investigate their over-completeness and show that they allow the resolution of unity in the form of an ordinary integral (for Q = pq < 1) or a generalized Q-deformed one (for Q = pq > 1). We study in detail analytically and numerically some of the geometrical and physical properties of these deformed coherent states in the context of deformed quantum optics. In particular, we show that for Q > 1 they exhibit sub-Poissonian statistics and no quadrature squeezing occurs while for Q < 1 their photon number statistics is super-Poissonian and there is a simultaneous squeezing in both field quadratures (double squeezing). Additionally, by a natural extension, we construct the corresponding multi-photon deformed coherent states and investigate their properties.
Journal of Physics A: Mathematical and General (03054470) 37(21)pp. 5649-5660
We establish some of the properties of the states interpolating between number and coherent states denoted by |n〈λ; among them are the reproduction of these states by the action of an operator-valued function on |n〈 (the standard Fock space) and the fact that they can be regarded as f -deformed coherent bound states. In this paper we use them as the basis of our new Fock space which in this case is not orthogonal but normalized. Then by some special superposition of them we obtain new representations for coherent and squeezed states in the new basis. Finally the statistical properties of these states are studied in detail.
Journal of Physics A: Mathematical and General (03054470) 37(15)pp. 4407-4422
Starting with the canonical coherent states, we demonstrate that all the so-called nonlinear coherent states, used in the physical literature, as well as large classes of other generalized coherent states, can be obtained by changes of bases in the underlying Hubert space. This observation leads to an interesting duality between pairs of generalized coherent states, bringing into play a Gelfand triple of (rigged) Hubert spaces. Moreover, it is shown that in each dual pair of families of nonlinear coherent states, at least one family is related to a (generally) non-unitary projective representation of the Weyl-Heisenberg group, which can then be thought of as characterizing the dual pair.
Journal of Physics A: Mathematical and General (03054470) 37(33)pp. 8111-8127
Considering some important classes of generalized coherent states known in the literature, we demonstrated that all of them can be created via conventional methods, i.e. the 'lowering operator eigenstate' and the 'displacement operator' techniques using the 'nonlinear coherent states' approach. As a result we obtained a 'unified method' to construct a large class of coherent states which have already been introduced by different prescriptions.