We propose an optomechanical setup allowing quantum mechanical correlation, entanglement and steering of two ultrashort optical pulses. The protocol exploits an indirect interaction between the pulses mediated optomechanically by letting both interact twice with a highly noisy mechanical system. We prove that significant entanglement can be reached in the bad cavity limit, where the optical decay rate exceeds all other damping rates of the optomechanical system. Moreover, we demonstrate that the protocol generates a quantum non-demolition interaction between the ultrashort pulses which is the basic gate for further applications.
We propose an optomechanical setup allowing quantum mechanical correlation, entanglement and steering of two ultrashort optical pulses. The protocol exploits an indirect interaction between the pulses mediated optomechanically by letting both interact twice with a highly noisy mechanical system. We prove that significant entanglement can be reached in the bad cavity limit, where the optical decay rate exceeds all other damping rates of the optomechanical system. Moreover, we demonstrate that the protocol generates a quantum non-demolition interaction between the ultrashort pulses which is the basic gate for further applications.
We propose a setup allowing to entangle two directly non-interacting radiation modes applying four sequential pulsed quantum resonant interactions with a noisy vibrational mode of a mechanical oscillator which plays the role of the mediator. We analyze Gaussian entanglement of the radiation modes generated by the transducer and confirm that the noisy mechanical mode can mediate generation of entanglement. The entanglement, however, is limited if the interaction gains are not individually optimized. We prove the robustness of the transducer to optical losses and the influence of the mechanical bath and propose the ways to achieve maximal performance through the individual optimization.
Abstract Entanglement generation at a macroscopic scale offers an exciting avenue to develop new quantum technologies and study fundamental physics on a tabletop. Cavity quantum optomechanics provides an ideal platform to generate and exploit such phenomena owing to the precision of quantum optics combined with recent experimental advances in optomechanical devices. In this work, we propose schemes operating outside the resolved-sideband regime, to prepare and verify both optical–mechanical and mechanical–mechanical entanglement. Our schemes employ pulsed interactions with a duration much less than the mechanical period and, together with homodyne measurements, can both generate and characterize these types of entanglement. To improve the performance of our schemes, a precooling stage comprising prior pulses can be utilized to increase the amount of entanglement prepared, and local optical squeezers may be used to provide resilience against open-system dynamics. The entanglement generated by our schemes is quantified using the logarithmic negativity and is analysed with respect to the strength of the pulsed optomechanical interactions for realistic experimental scenarios including mechanical decoherence and optical loss. Two separate schemes for mechanical entanglement generation are introduced and compared: one scheme based on an optical interferometric design, and the other comprising sequential optomechanical interactions. The pulsed nature of our protocols provides more direct access to these quantum correlations in the time domain, with applications including quantum metrology and tests of quantum decoherence. By considering a parameter set based on recent experiments, the feasibility to generate significant entanglement with our schemes, even with large optical losses, is demonstrated.
A novel protocol for generating quantum superpositions of macroscopically distinct states of a bulk mechanical oscillator is proposed, compatible with existing optomechanical devices operating in the bad-cavity limit. By combining a pulsed optomechanical quantum nondemolition (QND) interaction with nonclassical optical resources and measurement-induced feedback, the need for strong single-photon coupling is avoided. We outline a three-pulse sequence of QND interactions encompassing squeezing-enhanced cooling by measurement, state preparation, and tomography.
ABSTRACT This study investigates the creation of entanglement and quantum steering within a two-cavity optomechanical setup linked through photon hopping. One of the cavities exhibits nonlinear gain, whereas the other interacts with a mechanical oscillator. Our results show that photon hopping enables the transfer of quantum correlations among the subsystems. Furthermore, we explore these multipartite dynamics under practical conditions that account for thermal noise, detuning, and mechanical damping. The results reveal that photon hopping plays a crucial role in strengthening both quantum steering and entanglement between the optical and mechanical modes. An increase in nonlinear gain enhances the extent of quantum correlations, whereas the detuning parameter provides an additional means of control for optimizing system performance. Moreover, the robustness of entanglement and steering against thermal noise demonstrates that photon hopping effectively maintains non-classical correlations even in noisy environments. The findings indicate that photon hopping effectively sustains multiple instances of quantum steering among different subsystems while also initiating entanglement generation. By deepening the understanding of the interplay between photon tunneling and optomechanical coupling, this study provides important insights for the design of hybrid quantum networks. These systems hold strong potential for applications in distributed sensing, quantum communication, and scalable quantum information processing platforms. Key Words: Entanglement, Steering, Optomechanical, Photon Hopping, Discord.
ABSTRACT This study investigates the creation of entanglement and quantum steering within a two-cavity optomechanical setup linked through photon hopping. One of the cavities exhibits nonlinear gain, whereas the other interacts with a mechanical oscillator. Our results show that photon hopping enables the transfer of quantum correlations among the subsystems. Furthermore, we explore these multipartite dynamics under practical conditions that account for thermal noise, detuning, and mechanical damping. The results reveal that photon hopping plays a crucial role in strengthening both quantum steering and entanglement between the optical and mechanical modes. An increase in nonlinear gain enhances the extent of quantum correlations, whereas the detuning parameter provides an additional means of control for optimizing system performance. Moreover, the robustness of entanglement and steering against thermal noise demonstrates that photon hopping effectively maintains non-classical correlations even in noisy environments. The findings indicate that photon hopping effectively sustains multiple instances of quantum steering among different subsystems while also initiating entanglement generation. By deepening the understanding of the interplay between photon tunneling and optomechanical coupling, this study provides important insights for the design of hybrid quantum networks. These systems hold strong potential for applications in distributed sensing, quantum communication, and scalable quantum information processing platforms. Key Words: Entanglement, Steering, Optomechanical, Photon Hopping, Discord.
Quantum entanglement and squeezing associated with the motions of massive mechanical oscillators play an essential role in both fundamental science and emerging quantum technologies, yet realizing such macroscopic nonclassical states remains a formidable challenge. In this paper, we investigate how to achieve strong optomechanical entanglement and mechanical squeezing in a membrane-embedded cavity optomechanical system incorporating a coherent feedback loop, where the membrane interacts with the cavity mode through both linear and quadratic optomechanical couplings. This hybrid optomechanical architecture offers a flexible tunability of intrinsic system parameters, thereby enabling controlled stiffening or softening of the mechanical mode through adjusting quadratic optomechanical coupling, as well as effective modulation of the cavity decay rate via feedback control. More importantly, the synergistic interplay effect allows for a strategic reconfiguration of the system's stability regime, which in turn permits the presence of significantly enhanced effective optomechanical coupling strengths before entering the unstable regime. Exploiting these unique features, we demonstrate that optomechanical entanglement can be substantially enhanced with positive coupling sign and suitable feedback parameters, while strong mechanical squeezing beyond the 3dB limit is simultaneously achieved over a broad parameter range with negative coupling sign, reaching squeezing degree above 10dB under optimized conditions. Our proposal, establishing an all-optical method for generating highly entangled or squeezed states in cavity optomechanical systems, opens up a new route to explore macroscopic quantum effects and to advance quantum information processing.