Search

We study theoretically the generation of mechanical squeezing and optomechanical entanglement in a double-cavity optomechanical system involving a modulated optical parametric amplifier (OPA). Owing to the cooperation of the modulated OPA and the auxiliary cavity, the mechanical squeezing can be realized in both the resolved-sideband and unresolved-sideband regimes. Particularly, the strong mechanical squeezing can be generated in the resolved-sideband regime with the assistance of the modulated OPA. Moreover, under the joint effect of the auxiliary cavity and the modulated OPA, the optomechanical entanglement can be greatly enhanced in the unresolved-sideband regime. It is noted that both the mechanical squeezing and optomechanical entanglement have strong robustness against the high dissipation of the cavity and thermal noise. [ABSTRACT FROM AUTHOR]

Small extracellular vesicles (sEVs) are recognized as promising detection biomarkers and attractive delivery vehicles, showing great potential in diagnosis and treatment of diseases. However, the applications of sEVs are usually restricted by their poor secretion amount from donor cells under routine cell culture conditions, which is especially true for mesenchymal stem cells (MSCs) due to their limited expansion and early senescence. Here, a microfluidic device is proposed for boosting sEV secretion from MSCs derived from human fetal bone marrow (BM-MSCs). As the cells rapidly pass through a microfluidic channel with a series of narrow squeezing ridges, mechanical stimulation permeabilizes the cell membrane, thus promoting them to secrete more sEVs into extracellular space. In this study, the microfluidic device demonstrates that mechanical-squeezing effect could increase the secretion amount of sEVs from the BM-MSCs by approximately 4-fold, while maintaining cellular growth state of the stem cells. Further, the secreted sEVs are efficiently taken up by immortalized human corneal epithelial cells and accelerate corneal epithelial wound healing in vitro, indicating that this technique wound not affect the functionality of sEVs and demonstrating the application potentials of this technique.

We investigate the entanglement and mechanical squeezing of a hybrid system formed by two two-level atomic ensembles and a dissipative optomechanical system driven by two lasers. We find the entanglement of two atomic ensembles can be adjusted by the dissipative and dispersive couplings of the system. If the dispersive coupling is taken into account, the maximal entanglement between atomic ensembles could be larger than that of the purely dissipative case. Then, we show that there is steady-state entanglement in the present dissipative optomechanics systems and it increases with the mechanical oscillator decay rate and driving laser power. Finally, a strong mechanical squeezing of more than 3 dB is generated in the dissipative atom-photomechanical hybrid systems. [ABSTRACT FROM AUTHOR]

A scheme to generate mechanical squeezing of phonon mode in a hybrid cavity magnomechanical system composed of a yttrium iron garnet sphere and two auxiliary cavities and driven by a two‐tone laser is proposed. It is found that the strong mechanical squeezing can be generated by optimizing the ratio of blue‐detuned to red‐detuned laser amplitude. However, the mechanical squeezing can not be generated when the blue‐detuned laser is not applied. Furthermore, it is found that the two auxiliary cavities suppress the effect of the counter‐rotating terms, leading to that the mechanical squeezing can break the 3 dB$\rm dB$ limit even when the dissipation rate of the magnon mode is much larger than the mechanical frequency. By contrast, if only one auxiliary cavity or no auxiliary cavity is coupled to magnon mode, the mechanical squeezing beyond 3 dB$\rm dB$ can not be achieved in a high dissipation of the magnon mode. This scheme provides an alternative way toward the practical implementation of mechanical squeezing in a hybrid cavity magnomechanical system. [ABSTRACT FROM AUTHOR]

In this paper, the macroscopic quantum entanglement and squeezing in an unresolved‐sideband atom‐optomechanical system with a modulated optical parametric amplifier (OPA) inside the cavity are studied. Increasing the parametric gain of the OPA, the quantum‐classical correspondence between the atom‐mirror entanglement and classical nonlinear dynamics can be found. The critical point where the system experiences the transition from periodic oscillation to period‐doubling motion can be characterized by the singularity of the atom–mirror entanglement. Furthermore, the dependence of the atom–mirror entanglement and mechanical squeezing on the detuning and the parametric gain of the OPA as well as the environment temperature are investigated in detail. It is found that the atom‐mirror entanglement can be enhanced and the mechanical squeezing can be generated by modulating the OPA. [ABSTRACT FROM AUTHOR]

We introduce a unitary operator which may be constructed conveniently by exploiting the properties of the Glauber displacement and parity operators. We show that it can be considered as a constant of motion of a quantum system including pure dephasing interaction of a central qubit with a nano-mechanical resonator. Using the eigenvectors of the Glauber displacement operator, we paves a way for an extensive study of the dynamics of resonator-qubit states. In addition, we show that the establishment of such a constant of motion, which includes the parity operator, provides a way to introduce a capable mechanical framework to generate some desired mechanical state as superposition of the Glauber coherent states. We investigate nonclassical properties of the generated mechanical states, by evaluating mechanical-squeezing, Wigner function, position–momentum entropic squeezing, and entanglement between spin-mechanical modes. Furthermore, the pairwise classical and quantum correlations are derived based on a necessary and sufficient condition for the zero-discord state. Finally, in order to study the mechanical state's behavior in an environment, we consider that the output state is subject to amplitude (phase)-damping channels and their dissipative properties are analyzed. [ABSTRACT FROM AUTHOR]

We consider a thermodynamic machine in which the working fluid is a quantized harmonic oscillator that is controlled on timescales that are much faster than the oscillator period. We find that operation in this ‘fast’ regime allows access to a range of quantum thermodynamical behaviors that are otherwise inaccessible, including heat engine and refrigeration modes of operation, quantum squeezing, and transient cooling to temperatures below that of the cold bath. The machine involves rapid periodic squeezing operations and could potentially be constructed using pulsed optomechanical interactions. The prediction of rich behavior in the fast regime opens up new possibilities for quantum optomechanical machines and quantum thermodynamics.

Einstein–Podolski–Rosen (EPR) entanglement states are achievable by combining two single-mode position and momentum squeezed states at a 50:50 beam splitter (BS). To generate the EPR mechanical entanglement, we consider the system consisted of two parametric optomechanical resonators, where two mechanical oscillators are linearly coupled. The linear coupling forms the symmetric and antisymmetric combinations of two mechanical modes, parallel to a 50:50 BS mixing. In the weak optomechanical coupling regime and via applying the opposite phases of parametric interactions, the symmetric and antisymmetric mechanical modes can be position and momentum squeezed, respectively. Therefore, two original mechanical modes are EPR entangled. Moreover, the mechanical thermal noise can decrease the entanglement. But with the parametric interaction enhanced optomechanical cooling, the influence of thermal noise on entanglement can be significantly suppressed, and the mechanical entanglement can be generated under a relatively high temperature. We also discuss the critical thermal occupation where the entanglement disappears, which is proportional to the optomechanical cooperativity parameter. [ABSTRACT FROM PUBLISHER]

Macroscopic mechanical oscillators can be prepared in quantum states and coherently manipulated using the optomechanical interaction. This has recently been used to prepare squeezed mechanical states. However, the scheme used in these experiments relies on slow, dissipative evolution that destroys the system’s memory of its initial state. In this paper we propose a protocol based on a sequence of four pulsed optomechanical interactions. In addition to being coherent, our scheme executes in a time much shorter than a mechanical period. We analyse applications in impulsive force sensing and preservation of Schrödinger cat states, which are useful in continuous-variable quantum information protocols.

Measurements of δ2H and δ18O composition of pore waters in saturated and unsaturated soil samples are routinely performed in hydrological studies. A variety of in-situ and lab-based pore water extraction methods for the analysis of the stable isotopes of water now exist. While some have been used for decades (e.g. cryogenic vacuum extraction) others are relatively new, such as direct vapour equilibration or the microwave extraction technique. Despite their broad range of application, a formal and comprehensive intercomparison of soil water extraction methods for stable isotope analysis is lacking and long overdue. Here we present an intercomparison among five commonly used lab-based pore water extraction techniques (high pressure mechanical squeezing, centrifugation, direct vapour equilibration, microwave extraction, and cryogenic extraction). We applied these extraction methods to two physicochemically different soil types that were dried and rewetted with water of known isotopic composition at three different water contents. Our results showed that the extraction approach can have a significant effect on pore water isotopic composition as all methods exhibited significant deviations from the spiked reference water, depending secondarily on the soil type and soil water content. Most pronounced, cryogenic water extraction showed large deviations from the spiked reference water, whereas mechanical squeezing and centrifugation provided results closest to the spiked water for both soil types. We also compared results for each extraction method - where liquid water was obtained - on both an OA-ICOS and IRMS. Differences between these two analytical instruments were negligible for these organic compound-free waters. We suggest that users of soil water extraction approaches carefully choose an extraction technique that is suitable for the specific research question, adapted to the dominant soil type and water content of the study. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Small extracellular vesicles (sEVs) are recognized as promising detection biomarkers and attractive delivery vehicles, showing great potential in diagnosis and treatment of diseases. However, the applications of sEVs are usually restricted by their poor secretion amount from donor cells under routine cell culture conditions, which is especially true for mesenchymal stem cells (MSCs) due to their limited expansion and early senescence. Here, a microfluidic device is proposed for boosting sEV secretion from MSCs derived from human fetal bone marrow (BM-MSCs). As the cells rapidly pass through a microfluidic channel with a series of narrow squeezing ridges, mechanical stimulation permeabilizes the cell membrane, thus promoting them to secrete more sEVs into extracellular space. In this study, the microfluidic device demonstrates that mechanical-squeezing effect could increase the secretion amount of sEVs from the BM-MSCs by approximately 4-fold, while maintaining cellular growth state of the stem cells. Further, the secreted sEVs are efficiently taken up by immortalized human corneal epithelial cells and accelerate corneal epithelial wound healing in vitro , indicating that this technique wound not affect the functionality of sEVs and demonstrating the application potentials of this technique., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

• The strong mechanical squeezing is achieved by nonlinearity and two driving lasers. • The squeezing can be manipulated by the amplitude and ratio of two driving lasers. • The robustness of squeezing to the thermal noise is raised by enhancing laser power. • The squeezing can be directly detected by homodyning the cavity output field. • The joint idea opens up an alternative way to engineer strong mechanical squeezing. We propose a scheme to engineer strong steady-state mechanical squeezing via the joint effect between Duffing nonlinearity and two driving tones in an optomechanical system. It is found that the joint effect can achieve strong squeezing exceeding 3 dB when the amplitude ratio of two driving tones is large enough. Moreover, the generated squeezing can be flexibly manipulated by increasing the red-detuned laser power and selecting the amplitude ratio of two driving lasers. The robustness of mechanical squeezing set up by the joint effect to the thermal noise can be improved benefiting from the enhancement of red-detuned laser power. Furthermore, we present that the mechanical squeezing can be directly detected by homodyning the cavity output field under an appropriate phase. [ABSTRACT FROM AUTHOR]

This paper gives a brief review of the basic physics of quantum optomechanics and provides an overview of some of its recent developments and current areas of focus. It first outlines the basic theory of cavity optomechanical cooling and gives a brief status report of the experimental state-of-the-art. It then turns to the deep quantum regime of operation of optomechanical oscillators and covers selected aspects of quantum state preparation, control and characterization, including mechanical squeezing and pulsed optomechanics. This is followed by a discussion of the 'bottom-up' approach that exploits ultracold atomic samples instead of nanoscale systems. It concludes with an outlook that concentrates largely on the functionalization of quantum optomechanical systems and their promise in metrology applications. [ABSTRACT FROM AUTHOR]

Generation of strong stationary optical and mechanical squeezing is proposed for the linear‐and‐quadratic optomechanical system, where two cavity modes induce linear and quadratic optomechanical couplings, respectively. Through the linearization treatment, linearized coupling between cavity mode and mechanical mode and the mechanical parametric amplification process are achievable and controllable by independent driving lasers. Optical and mechanical squeezing are generated following different mechanisms. Optical squeezing works in the strong coupling regime, and mechanical amplification would push the system close to instability threshold, which could deeply improve ponderomotive squeezing even significantly beyond the 3 dB squeezing limit. Mechanical squeezing is generated based on the reservoir engineering method, where parametric amplification induces the squeezing transformation of mechanical mode; and linearized coupling, which operates in the red‐sideband and weak coupling limits, induces the ground‐state cooling of transformed mechanical mode. Finally, the original mechanical mode would be squeezed, which could also exceed 3 dB limit. [ABSTRACT FROM AUTHOR]

A hybrid optomechanical system which is composed of an atomic ensemble and a standard optomechanical cavity driven by a periodically modulated external laser field is investigated. Based on the simple periodic modulation forms of the driving amplitude and effective optomechanical coupling, respectively, the atom‐mirror entanglement is discussed in detail. It is found that the maximum of the entanglement in the unresolved‐sideband regime can be further enhanced compared with the non‐modulation regime. On the other hand, we find that the introduction of the atomic ensemble permits the mechanical squeezing induced by the periodic amplitude modulation can be successfully generated even in the unresolved‐sideband regime. Due to the self‐cooling mechanism constructed by the atomic ensemble, the mechanical squeezing scheme no longer requires the extra precooling technologies. [ABSTRACT FROM AUTHOR]