Quantum entanglement is pivotal in modern quantum technologies, spanning applications from quantum networks to quantum metrology. Controllable quantum entanglement in cavity optomechanical systems has been an enduring pursuit. We propose a unique method for flexible manipulation and switching of optomechanical entanglement in a squeezed-cavity-assisted optomechanical system consisting of a χ (2) -nonlinear optical cavity and an optomechanical cavity. Squeezing the nonlinear optical cavity through parametric pumping allows effective control of light-light and light-vibration interactions within the system. This capability of the squeezed system plays a key role in manipulating quantum entanglement. We find that quantum entanglement between the unsqueezed cavity mode and the mechanical mode can be effectively regulated by adjusting the pump laser parameters. Furthermore, by turning the phase of the pump, we can achieve highly flexible quantum switching between entanglement and separability. Additionally, we demonstrate increased entanglement between the squeezed cavity mode and the mechanical mode when completely suppressing the pump-induced optical input noise. Our findings pave the way not only towards the manipulation and protection of fragile quantum entanglement but also to achieve photon-phonon quantum control by exploiting quantum squeezing.
Quantum entanglement is pivotal in modern quantum technologies, spanning applications from quantum networks to quantum metrology. Controllable quantum entanglement in cavity optomechanical systems has been an enduring pursuit. We propose a unique method for flexible manipulation and switching of optomechanical entanglement in a squeezed-cavity-assisted optomechanical system consisting of a χ (2) -nonlinear optical cavity and an optomechanical cavity. Squeezing the nonlinear optical cavity through parametric pumping allows effective control of light-light and light-vibration interactions within the system. This capability of the squeezed system plays a key role in manipulating quantum entanglement. We find that quantum entanglement between the unsqueezed cavity mode and the mechanical mode can be effectively regulated by adjusting the pump laser parameters. Furthermore, by turning the phase of the pump, we can achieve highly flexible quantum switching between entanglement and separability. Additionally, we demonstrate increased entanglement between the squeezed cavity mode and the mechanical mode when completely suppressing the pump-induced optical input noise. Our findings pave the way not only towards the manipulation and protection of fragile quantum entanglement but also to achieve photon-phonon quantum control by exploiting quantum squeezing.
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.
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.
Abstract The ability to engineer entangled states that involve macroscopic objects is of particular importance for a wide variety of quantum‐enabled technologies, ranging from quantum information processing to quantum sensing. Here how to achieve coherent manipulation and enhancement of quantum entanglement in a hybrid optomechanical system, which consists of a Fabry–Pérot cavity with two movable mirrors, an optical parametric amplifier (OPA), and an injected squeezed vacuum reservoir is proposed. It is shown that the advantages of this system are twofold: 1) one can effectively regulate the light‐mirror interactions by introducing a squeezed intracavity mode via the OPA; 2) when properly matching the squeezing parameters between the squeezed cavity mode and the injected squeezed vacuum reservoir, the optical input noises can be suppressed completely. These peculiar features of this system allow the generation and manipulation of quantum entanglement in a coherent and controllable way. More importantly, it is also found that such controllable entanglement, under some specific squeezing parameters, can be considerably enhanced in comparison with those of the conventional optomechanical system. The work, providing a promising method to regulate and tailor the light‐mirror interaction, is poised to serve as a useful tool for engineering various quantum effects which are based on cavity optomechanics.
We propose a theoretical project in which quantum squeezing induces quantum entanglement and Einstein-Podolsky-Rosen steering in a coupled whispering-gallery-mode optomechanical system. Through pumping the χ (2) -nonlinear resonator with the phase matching condition, the generated squeezed resonator mode and the mechanical mode of the optomechanical resonator can generate strong quantum entanglement and EPR steering, where the squeezing of the nonlinear resonator plays the vital role. The transitions from zero entanglement to strong entanglement and one-way steering to two-way steering can be realized by adjusting the system parameters appropriately. The photon-photon entanglement and steering between the two resonators can also be obtained by deducing the amplitude of the driving laser. Our project does not need an extraordinarily squeezed field, and it is convenient to manipulate and provides a novel and flexible avenue for diverse applications in quantum technology dependent on both optomechanical and photon-photon entanglement and steering.
As classical technology approaches its limits, exploration of quantum technologies is critical. Quantum optics will be the basis of various cutting-edge research and applications in quantum technology. In particular, quantum optics quite efficacious when applied to quantum networks and the quantum internet. Quantum Optomechanics, a subfield of quantum optics, contains some novel methods for entanglement generation. These entanglement production methods exploit the noise re-encoding process, which is most often associated with creating unwanted phase noise in optical circuits. Using the adapted two-photon formalism and experimental results, we simulate (in an experimentally viable parameter space) optomechanical entanglement generation experiments. These simulations consider dual coherent field input, displaced single-mode squeezed input, and displaced two-mode squeezed inputs. Unsqueezed inputs should yield an EN of about 0.1 at room temperature, although very high measurement certainty is needed to observe this in the laboratory. Squeezing the displaced input fields increases the expected output entanglement significantly (maximum of EN of about 1). Furthermore, when considering dual two-mode squeezed input (4 fields) in the simulation, the optomechanical cavity demonstrates squeezing angle-dependent entanglement distribution.
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 entanglement between the phonon modes.