Double-cavity Optomechanical System Research Articles

Improving the Performance of Cooling and Entanglement in a Double Cavity Optomechanical System Assisted by the Quantum Coherent Feedback

AbstractA theoretical scheme is proposed for improving the performance of cooling and entanglement, where the physical model is based on a double cavity optomechanical system assisted by the field‐mediated coherent feedback. The cooling performance is evaluated by calculating the final mean phonon number. The steady‐state bipartite entanglement between the optical mode and mechanical mode is measured by the logarithmic negativity. The result manifests that with assistance of the quantum coherent feedback, the mechanical resonator (MR) can be cooled close to its quantum ground state and the steady‐state optomechanical entanglement is simultaneously created, all of which are obtained under the condition beyond the resolved sideband. The presented feedback strategy is measurement‐independent, which can effectively preserve the quantum coherence of system. The scheme is conducive to relaxing the current experimental condition and it may provide a new path for the optomechanical manipulation involving the low‐frequency MR.

Conventional and Unconventional Photon Blockade in a Double-Cavity Optomechanical System

Conventional and Unconventional Photon Blockade in a Double-Cavity Optomechanical System

Effects of cross-Kerr coupling on transmission spectrum of double-cavity optomechanical system

We theoretically study the transmission spectrum of the cavity field in a double-cavity optomechanical system with cross-Kerr (CK) effect. The system consists of two tunneling coupling optomechanical cavities with a mechanical resonator as a coupling interface. By doping CK medium into the mechanical resonator, CK couplings between the cavity fields and the mechanical resonator are introduced. We investigate the effects of CK coupling strength on the transmission spectrum of the cavity field, including the transmission rate, nonreciprocity and four-wave mixing (FWM). We find that the transmission spectrum of the probe field can show two obvious transparent windows, which can be widened by increasing the CK coupling strength. For the transmission between the two cavity fields, the perfect nonreciprocity and reciprocity are present and modulated by CK coupling and phase difference between two effective optomechanical couplings. In addition, the effects of the optomechanical and CK couplings on FWM show that the single peak of FWM is split into three symmetrical peaks due to the introduction of the CK effect.

Optomechanical squeezing and entanglement in cavities optomechanical system

We present the squeezing and entanglement features of the vibrational phonon modes in a double-cavity optomechanical system with input squeezed light. The non-classical features of the vibrational phonon modes arise from the transfer of quantum coherence from the optical to the phonon modes. The phonon modes exhibit squeezing, and the degree of squeezing increases with the increase in the input squeezed light. To quantify the entanglement between the phonon modes, we apply the Hillery and Zubairy criterion. We demonstrate that the entanglement between the phonon modes increases with an increase in optomechanical cooperativity. Moreover, the input squeezed light has a substantial effect on the degree entanglement between the phonon modes.

Nonreciprocal coupling modulated difference-sideband generation in a double-cavity optomechanical system.

We theoretically study the difference-sideband generation in a double-cavity optomechanical system with nonreciprocal coupling. Beyond the conventional linearized description of optomechanical interactions, we derive analytical expressions for the efficiency of difference-sideband generation by using a perturbation method. Here we investigate bistable behaviors of the system and show the difference-sideband generation modulated by the nonreciprocal coupling strength between the two cavities. We find that the nonreciprocal coupling strength can not only affect the bistability of the system but also lead to different efficiencies of difference-sideband generation at low power. To achieve high efficiency of difference-sideband generation, we give the optimal matching conditions under different parameter mechanisms. Especially as the power increases, we find new matching conditions with remarkable difference-sideband generation emerging, which is attribute to the strong coherence between the cavity field and the mechanical oscillator. Furthermore, a feasible scheme to obtain difference-sideband generation by employing multiple adjustable variables is proposed. Our results may find applications in nonreciprocal optical frequency combs and communications, and provide a potential method for precision measurements and on-chip manipulation of light transmission.

Strong photon antibunching effect in a double-cavity optomechanical system with intracavity squeezed light

Strong photon antibunching effect in a double-cavity optomechanical system with intracavity squeezed light

Study of optical bistability in a double-cavity hybrid optomechanical system consisting of an optical cavity coupled with a mechanical resonator filled with semiconductor quantum dot molecules

Study of optical bistability in a double-cavity hybrid optomechanical system consisting of an optical cavity coupled with a mechanical resonator filled with semiconductor quantum dot molecules

Nonreciprocal photon blockade in a spinning optomechanical system with nonreciprocal coupling.

A scheme is presented to achieve quantum nonreciprocity by manipulating the statistical properties of the photons in a composite device consisting of a double-cavity optomechanical system with a spinning resonator and nonreciprocal coupling. It can be found that the photon blockade can emerge when the spinning device is driven from one side but not from the other side with the same driving amplitude. Under the weak driving limit, to achieve the perfect nonreciprocal photon blockade, two sets of optimal nonreciprocal coupling strengths are analytically obtained under different optical detunings based on the destructive quantum interference between different paths, which are in good agreement with the results obtained from numerical simulations. Moreover, the photon blockade exhibits thoroughly different behaviors as the nonreciprocal coupling is altered, and the perfect nonreciprocal photon blockade can be achieved even with weak nonlinear and linear couplings, which breaks the orthodox perception.

Modulation of the second-order sideband efficiency of a double-cavity optomechanical system by mechanical pumps

We study the effect of external mechanical pumps on the second-order sideband generation (SSG) efficiency in a double-cavity optomechanical system. The SSG efficiency can be tuned by changing the amplitude and phase of the mechanical pumps. When external mechanical pumps are applied to both mechanical resonators, the influence on the SSG efficiency is a superposition of the two mechanical pumps driven separately. The SSG efficiency can be increased up to three times with the application of mechanical pumps compared to the case without external mechanical pumps. The present investigation proposes a method that can be applied to more cavity cascades to achieve more desirable SSG efficiency and optimize nonlinear optical properties.

Mechanical squeezing in an active-passive-coupled double-cavity optomechanical system via pump modulation.

We focus on the generation of mechanical squeezing by using periodically amplitude-modulated laser to drive an active-passive-coupled double-cavity optomechanical system, where the coupled gain cavity and loss cavity can form into a parity-time (P T)-symmetry system. The numerical analysis of the system stability shows that the system is more likely to be stable in the unbroken-P T-symmetry regime than in the broken-P T-symmetry regime. The mechanical squeezing in the active-passive system exhibits stronger robustness against the thermal noise than that in the passive-passive system, and the so-called 3 dB limit can be broken in the resolved-sideband regime. Furthermore, it is also found that the mechanical squeezing obtained in the unbroken-P T-symmetry region is stronger than that in the broken-P T-symmetry region. This work may be meaningful for the quantum state engineering in the gain-loss quantum system that contributes to the study of P T-symmetric physics in the quantum regime.

Quantum versus classical correlations in a double cavity optomechanical system

In a bipartite quantum state, where the total correlations can be divided into classical and quantum parts, Henderson and Vedral (2001 J. Phys. A: Math. Gen. 34 6899) have conjectured that classical correlations should not be less than quantum ones. Here, we consider two symmetrical states of two driven optomechanical cavities coupled to a squeezed photon source and exposed to Markovian noise and damping. The total and quantum correlations are systematically quantified by quantum mutual information and quantum discord respectively. Interestingly, we analytically demonstrate that classical correlations in the considered two-mode Gaussian states are always superior to quantum ones, whatever the physical and environmental parameters are. Moreover, using experimentally accessible parameters, we show numerically the existence of a domination of classical correlations over quantum ones under various circumstances. Finally, we found that quantum, as well as classical correlations, have similar behaviors under the effect of thermal decoherence, squeezing and optomechanical coupling. Yet, classical correlations are more strong and robust.

Nonreciprocal coupling induced entanglement enhancement in a double-cavity optomechanical system

We investigate the quantum entanglement in a double-cavity optomechanical system consisting of an optomechanical cavity and an auxiliary cavity, where the optomechanical cavity mode couples with the mechanical mode via radiation-pressure interaction, and simultaneously couples with the auxiliary cavity mode via nonreciprocal coupling. We study the entanglement between the mechanical oscillator and the cavity modes when the two cavities are reciprocally or nonreciprocally coupled. The logarithmic negativity () is adopted to describe the entanglement degree between the mechanical mode and the optomechanical cavity mode (the auxiliary cavity mode). We find that both and have maximum values in the case of reciprocal coupling. By using nonreciprocal coupling, and can exceed those maximum values, and a wider detuning region where the entanglement exists can be obtained. Moreover, the entanglement robustness with respect to the environment temperature is also effectively enhanced.

Suppression of Stokes heating processes and improved optomechanical cooling with frequency modulation

Ground-state cooling of mesoscopic mechanical objects is still a major challenge in the unresolved-sideband regime. We present a frequency modulation (FM) scheme to achieve cooling of the mechanical resonator to its ground-state in a double-cavity optomechanical system containing a mechanical resonator. The mean phonon number is determined by numerically solving a set of differential equations derived from the quantum master equations. Due to efficient suppression of Stokes heating processes in the presence of FM, the ground-state cooling, indicated by numerical calculations, is significantly achievable, regardless of whether in the resolved-sideband regime or the unresolved-sideband regime. Furthermore, by choosing parameters reasonably, the improvement of the quantum cooling limit is found to be capable of being positively correlated with the modulation frequency. This method provides new insight into quantum manipulation and creates more possibilities for applications of quantum devices.

Quantification of different quantum correlations in a double cavity optomechanical system

The aim of this paper is to quantify the quantum correlations between mechanical and optical modes in an optomechanical system with two spatially separated Fabry–Pérot cavities. We use logarithmic negativity [Formula: see text] and entanglement of formation (EoF), respectively, to quantify entanglement between optical and mechanical modes, while Gaussian geometric discord (GGD) is used to capture all nonclassical correlations, including entanglement. These quantifiers are evaluated as functions of the physical parameters characterizing the environment and the system (the thermal bath temperature [Formula: see text], the photons number [Formula: see text], the optomechanical cooperativity [Formula: see text], the squeeze parameter [Formula: see text] and the drive pump power [Formula: see text]). By considering recent experimental parameters, we show that GGD is more robust than entanglement for high thermal bath temperature and low optomechanical cooperativity. We also find that these quantifiers improve with increasing optomechanical cooperativity. The effects of the other parameters are also discussed in detail.

Controllable photon blockade in double-cavity optomechanical system with Kerr-type nonlinearity

Controllable photon blockade in double-cavity optomechanical system with Kerr-type nonlinearity

Chiral-dissipation-assisted generation of entanglement and asymmetric Gaussian steering in a driven cascaded quantum network

We study the dissipative dynamics and the formation of entangled states in a driven cascaded quantum network, where a cascaded double-cavity optomechanical system is coupled to a common unidirectional optical fiber. In terms of two coherent laser fields simultaneously driving the chiral coupling system, the entanglement can be effectively transferred from the light to two nanomechanical resonators (NMRs) through cavity modes based on the completely destructive interference of quantum noise. By adjusting the relative strength ratio of red- and blue-detuned pump lasers, it is found that the two NMRs can be driven into a mixed two-mode Gaussian entangled mechanical state rather than a non-Gaussian entangled dark state or a pure entangled dark state. If the frequency of the NMR is tuned to be much larger than the chiral coupled-cavity-chain damping rate, it is demonstrated that the chiral dissipative cascaded system can always realize one-way Einstein-Podolsky-Rosen (EPR) steering from one mechanical oscillator to the other, while the reverse one-way EPR steering is impossible to obtain, and the reason for achieving asymmetric Gaussian steering is analyzed. Furthermore, a simple one-way EPR steering criterion based on two-photon correlation can be achieved for an arbitrary bipartite Gaussian state under the standard form of EPR steering, and the effect of mechanical thermal noise on the steering is also discussed. Moreover, the present chiral system can be realized with currently available experimental technology; therefore, we hope that it can be very helpful for potential applications in quantum computation and quantum communication.

Optomechanically induced Faraday and splitting effects in a double-cavity optomechanical system

We demonstrate the optomechanically induced Faraday and splitting effects caused by optical mode conversion in a double-cavity optomechanical system. In the scheme, the polarization states of propagating light fields can be arbitrarily tailored to achieve optical Faraday rotation successfully via optomechanical interaction. Meanwhile, the energy-level splitting of the degenerate optical modes leads to the separation of two orthogonal polarization optical modes and the manipulation of spin angular momentum of photons. Moreover, the polarized output component orthogonal to the control field can be manipulated by properly choosing the tunneling interaction between two optical cavities, which enables the complete polarization control of the probe field. Using the polarized control field and optical gain in the auxiliary cavity, we can effectively improve the efficiency of optical Faraday rotation. Finally, we study how to achieve different optical control for different polarization states, which provides an effective method for the implementation of optical isolators in cavity optomechanical systems. Our scheme may benefit future realization of flexible controllability for the vector properties and spin angular momentum of photons, and can promote potential applications in optical nonreciprocal transport, routers, isolators, and circulators.

Geometric discord in a dissipative double-cavity optomechanical system

Geometric discord in a dissipative double-cavity optomechanical system

Effect of mechanical mode - qubit interaction on perfect optical non-reciprocity in double cavity system

Quantum devices exhibiting optical non-reciprocity are indispensable for quantum information processing and communication technology. In this paper we propose a double cavity optomechanical system where the movable mirror of the cavity is linearly coupled with a qubit placed inside the cavity. We study the effect of this mechanical mode - qubit linear interaction on time reversal symmetry i.e, optical non-reciprocity and prove that mechanical mode - qubit interaction can be used as a new tool to control optical non-reciprocity.

Tunable induced transparency and Fano-resonance in double cavity optomechanical system

We analyze optomechanically induced Transparency and asymmetric Fano-line shape Profile in a two-mode cavity system, coupling at weak and strong coupling regimes. The model system consists of one mechanical mode and two optical modes. The transmission shows nonreciprocal behavior. Both the forward transmission and backward reflection for the system are analyzed for both optic-optic and mechanical-optic cavities by considering various system parameters. The output spectra lead to sharp asymmetric Fano-resonance and tunable transparency. Double line-shape profile is observed in the output Spectrum. Our proposal provides a new platform for application in quantum telecommunications and a photonic device like optical Switches.