We study nonreciprocal bipartite and tripartite entanglement in a spinning exciton-optomechanical system (EOMS) with an optical parametric amplifier (OPA). We demonstrate that nonreciprocal entanglement among photons, excitons, and phonons can be achieved under experimentally feasible parameters. We find that the nonreciprocal entanglement induced by Sagnac effects can be regulated through the OPA. Particularly, We show that the OPA significantly enhances photon-exciton entanglement and tripartite entanglement but weakens photon-phonon and exciton-phonon entanglement. Moreover, we find that the photon-exciton nonreciprocal entanglement not only can be generated at room temperature and even higher temperature but also exhibits highly robustness to cavity dissipation. Our works open a way to manipulate the room-temperature nonreciprocal entanglement, which may be useful for developing nonreciprocal quantum technologies.
We study nonreciprocal bipartite and tripartite entanglement in a spinning exciton-optomechanical system (EOMS) with an optical parametric amplifier (OPA). We demonstrate that nonreciprocal entanglement among photons, excitons, and phonons can be achieved under experimentally feasible parameters. We find that the nonreciprocal entanglement induced by Sagnac effects can be regulated through the OPA. Particularly, We show that the OPA significantly enhances photon-exciton entanglement and tripartite entanglement but weakens photon-phonon and exciton-phonon entanglement. Moreover, we find that the photon-exciton nonreciprocal entanglement not only can be generated at room temperature and even higher temperature but also exhibits highly robustness to cavity dissipation. Our works open a way to manipulate the room-temperature nonreciprocal entanglement, which may be useful for developing nonreciprocal quantum technologies.
Cavity optomechanics, a promising platform to investigate macroscopic quantum effects, has been widely used to study nonreciprocal entanglement with the Sagnac effect. Here, we propose an alternative way to realize nonreciprocal entanglement among magnons, photons, and phonons in a hybrid cavity-magnon optomechanics, where the magnon Kerr effect is used. We show that the Kerr effect gives rise to a magnon frequency shift and an additional two-magnon effect. Both of them can be tuned from positive to negative via tuning the magnetic field direction, leading to nonreciprocity. By tuning system parameters such as magnon frequency detuning or the coefficient of the two-magnon effect, bipartite and tripartite entanglements can be nonreciprocally enhanced. By further studying the defined bidirectional contrast ratio, we find that nonreciprocity in our system can be switched on and off, and can be engineered by the bath temperature. Our proposal not only provides a potential path to demonstrate nonreciprocal entanglement with the magnon Kerr effect, but also opens a direction to engineer and design diverse nonreciprocal devices in hybrid cavity-magnon optomechanics with nonlinear effects.
We propose a method to enhance bipartite and tripartite entanglement in cavity magnomechanics using an optical parametric amplifier (OPA). We analyze this system and identified parametric regimes where different types of entanglement are enhanced. We show that a proper choice of phase of the parametric amplifier leads to the enhancement of the bipartite entanglements. Moreover, the tripartite entanglement is also significantly enhanced in the presence of the OPA. The OPA not only enhances the strength of entanglement but also increases the domain of entanglement over a wider space of detunings as compared to the system when no OPA is present. Similarly, the robustness of entanglement against temperature is also enhanced. Another important consequence of the OPA is the fact that it relaxes the requirement of strong magnon-phonon coupling to generate cavity-magnon entanglement which is necessary for the case when the OPA is not present. We believe that the presented scheme is a step forward to realize robust quantum entanglement using current technology.
The entanglement of different macroscopic objects can provide crucial resources for various quantum applications and quantum-enabled devices. The generation, manipulation, and enhancement of entanglement are pivotal areas of research. In this study, we introduce an approach for producing enhanced nonreciprocal entanglement in a hybrid spinning optomechanical system. By exploiting the Sagnac effect to break the time-reversal symmetry of the system, we successfully generate and amplify the nonreciprocal bipartite entanglement between the atomic ensemble and mechanical oscillator, exhibiting an approximately twofold enhancement under competitive equilibrium conditions. Furthermore, we investigate and quantify the nonreciprocal tripartite entanglement encompassing the atomic ensemble, optical cavity, and mechanical oscillator by employing the residual contangle measurement. We find that the nonreciprocal bipartite (tripartite) entanglement is not only enlarged almost two (five) times, but also noise resistant. The proposed scheme of enhanced bipartite and tripartite entanglement has the potential to advance a wide range of quantum technologies, spanning from quantum information processing to quantum sensing applications.
Tripartite entanglement as a remarkable resource in quantum information science has been extensively investigated in hybrid quantum systems, whereas it is generally weak and prone to be suppressed by noise, restricting its practical application in quantum technologies. Here, we propose how to enhance the tripartite entanglement among magnons, photons, and phonons in a hybrid cavity-magnon optomechanical system by exploiting a synergistic effect of the optical parametric amplification (OPA) and mechanical parametric amplification (MPA). We find that in the case of individually applying the OPA or MPA, the tripartite entanglement can be enhanced by several folds. Remarkably, upon suitably tuning the phase matching of the two parametric fields presented simultaneously, the strengths of the entanglement can be further enhanced due to the constructive interference between the OPA and MPA. We also show that our method can improve the robustness of the entanglement against thermal noise. Our work provides a promising method for manipulating the entanglement with easy tunability and may serve as a useful tool for the enhancement and protection of fragile quantum resources.
Multipartite quantum entanglement in PT-symmetric molecular optomechanics: Nonreciprocal enhancement and thermal resilience to \SI{500}{\kelvin}
We present a theoretical framework for a PT-symmetric double-cavity molecular optomechanical system demonstrating nonreciprocal enhancement of multipartite quantum entanglement at elevated temperatures. All bipartite entanglement channels (Eac, EaB1, EcB2, EB1B2) simultaneously maximize at optimal nonreciprocal asymmetry J1/J2≈5, with entanglement persisting to $T \sim \SIrange{400}{500}{\kelvin}$ (material-limited ceiling) two orders of magnitude beyond conventional optomechanical systems. This thermal resilience and balanced enhancement across all channels arise from synergistic combination of ultra-high-frequency molecular vibrations ($ω_m/2π= \SI{30}{\tera\hertz}$), collective N coupling enhancement with $N=\num{e6}$ molecules, and directional nonreciprocal coupling shielding entanglement-generating interactions from backaction noise. Unlike optical parametric amplifier schemes where vibration-vibration enhancement suppresses optical-vibration correlations, our PT-symmetric architecture circumvents this fundamental trade-off, validated through rigorous stability analysis via Routh-Hurwitz criterion.