Optomechanical System Research Articles

A novel architecture for room temperature microwave optomechanical experiments

We have developed a novel architecture for room temperature microwave cavity optomechanics, which is based on the coupling of a 3D microwave re-entrant cavity to a compliant membrane. Device parameters have enabled resolving the thermomechanical motion of the membrane and observing optomechanically induced transparency/absorption in the linear regime for the first time in a microwave optomechanical system operated at room temperature. We have extracted the single-photon coupling rate (g0) using four independent measurement techniques and, hence, obtained a full characterization of the proposed cavity optomechanical system.

Damping in precision vibration control: A review

This paper reviews various damping techniques used in precision vibration control devices such as optical tables and other vibration-isolated platforms for sensitive optical, acoustical, and life sciences experiments, as well as advanced technological processes [1]. These techniques include tunable dynamic vibration absorbers, active damping, and modal damping in isolated platforms, as well as active and passive damping in vibration isolators. The theoretical background, principles of implementation, and test results are illustrated by case studies that include a large tuned-damped optical bench in a petawatt laser facility, multi-beam lithography enabled by active damping, effective damping of vibration-isolated workstation for experiments on animal hearing, and atomic force microscopy assisted by active vibration isolation. [1] V.M. Ryaboy, Vibration Control for Optomechanical Systems, World Scientific, 2022.

Dynamic Brillouin cooling for continuous optomechanical systems

Up until now, ground state cooling using optomechanical interaction is realized in the regime where optical dissipation is higher than mechanical dissipation. Here, we demonstrate that optomechanical ground state cooling in a continuous optomechanical system is possible by using backward Brillouin scattering while mechanical dissipation exceeds optical dissipation which is the common case in optical waveguides. The cooling is achieved in an anti-Stokes backward Brillouin process by modulating the intensity of the optomechanical coupling via a pulsed pump to suppress heating processes in the strong coupling regime. With such dynamic modulation, a significant cooling factor can be achieved, which can be several orders of magnitude lower than for the steady-state case. This modulation scheme can also be applied to Brillouin cooling generated by forward intermodal Brillouin scattering.

Enhanced sensing of optomechanically induced nonlinearity by linewidth suppression and optical bistability in cavity-waveguide systems.

We study the enhanced sensing of optomechanically induced nonlinearity (OMIN) in a cavity-waveguide coupled system. The Hamiltonian of the system is anti-PT symmetric, with the two involved cavities being dissipatively coupled via the waveguide. The anti-PT symmetry may break down when a weak waveguide-mediated coherent coupling is introduced. However, we find a strong bistable response of the cavity intensity to the OMIN near the cavity resonance, benefiting from linewidth suppression caused by the vacuum induced coherence. The joint effect of optical bistability and the linewidth suppression is inaccessible by the anti-PT symmetric system involving only dissipative coupling. Due to that, the sensitivity measured by an enhancement factor is greatly enhanced by two orders of magnitude compared to that for the anti-PT symmetric model. Moreover, the enhancement factor shows resistance to a reasonably large cavity decay and robustness to fluctuations in the cavity-waveguide detuning. Based on the integrated optomechanical cavity-waveguide systems, the scheme can be used for sensing different physical quantities related to the single-photon coupling strength and has potential applications in high-precision measurements with systems involving Kerr-type nonlinearity.

Nonlinear effects in a Floquet-driven optomechanical system

We investigate theoretically the nonlinear effects in a Floquet-driven optomechanical system with quadratic coupling. When the periodically modulated driving field is strong, we establish an effective time-dependent model to describe this system. Using the Keldysh approach, we calculate the retarded Green's function to study the response behavior of the system to external probing. We find that when the $n\mathrm{th}$ sideband of a probe field satisfies the condition of two-phonon resonance, the transparency window occurs. In addition, we find some abnormal behaviors of the output field, which have no counterpart in the standard optomechanical models. These results provide a promising platform for controlling light propagation and light manipulation operations which have potential applications in quantum precision measurement techniques.

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.

Higher-order sideband based on transparent windows in a two-cavity optomechanical system

We present a scheme to realize the regulation of single and double transparent windows in a two-cavity optomechanical device. By studying the output field through the two-cavity device, we not only show the transmission spectrum of the probe field and the second-order sideband process, but also analyze the physical mechanism of the induced transparency window and the efficiency of the second-order sideband process. Moreover, the optomechanically induced transparency window and the coupling of two cavities resulting in transparency window are discussed. We find that the transparency windows and the second-order sideband process can be modulated by the power of the control field and the coupling strength between two cavities. Our device is feasible for controlling light propagation, which might have potential application in quantum optical devices and quantum information networks.

Ultrasensitive displacement measurement with nonlinear optomechanical coupling and squeezed light injection

We propose an ultrasensitive displacement measurement scheme to overcome the standard quantum limit (SQL) in the unresolved sideband cavity optomechanical system with nonlinear optomechanical coupling and squeezed light injection. By introducing the optimized quantum correlation, which is enabled by suitable choices of the squeezing angle, squeezing level, power of the probe light, and measurement angle of homodyne detection, the off-resonant displacement sensitivity reaches 6 dB below the SQL in linear optomechanical coupling. In contrast, displacement sensitivities with a coherent probe plus variational readout and squeezed probe plus fixed measurement angle (phase quadrature) are 2.6 dB and 4.6 dB below the SQL, respectively. By combining linear and quadratic optomechanical coupling, we show that the displacement sensitivity can be further improved to 9.6 dB below the SQL. Our results have potential applications in gravitational-wave detectors, quantum metrology, and the search for dark matter.

Optomechanically-induced nonreciprocal conversion between microwave and optical photons.

We theoretically propose a scheme of the nonreciprocal conversion device between photons of two arbitrary frequencies in a hybrid cavity optomechanical system, where two optical cavities and two microwave cavities are coupled to two different mechanical resonators via radiation pressure. Two mechanical resonators are coupled together via the Coulomb interaction. We study the nonreciprocal conversions between both the same and different types of frequency photons. The device is based on multichannel quantum interference to break the time-reversal symmetry. Our results show the perfect nonreciprocity conditions. By adjusting the Coulomb interaction and the phase differences, we find that the nonreciprocity can be modulated and even transformed into reciprocity. These results provide new insight into the design of nonreciprocal devices, including isolators, circulators, and routers in quantum information processing and quantum networks.

Tunable phonon–atom interaction in a hybrid optomechanical system

We theoretically analyze a hybrid system consisting of a levitated neutral atom and a nanoparticle coupled to a cavity. The mechanical oscillator and the atom are effectively coupled to each other through the cavity photons as a bus. By adjusting the driving lasers, we can conveniently switch the phonon–atom coupling between Jaynes–Cummings (JC) and anti-JC forms, which can be used to manipulate the motional states of the mechanical oscillator. As an application, we prepare a superposition state of the mechanical oscillator via the effective phonon–atom interaction and investigate the effects of dissipation on the state generation.

A Review on Zernike Coefficient-Solving Algorithms (CSAs) Used for Integrated Optomechanical Analysis (IOA)

An integrated optomechanical analysis (IOA) can predict the response of an optomechanical system to temperature, gravity, vibrations, and other local loadings; thus, the normal operation of instruments under special conditions is guaranteed. Zernike polynomials are the most popular for fitting the IOA-derived mechanical deformation data. By solving the Zernike coefficients of all deformed optical surfaces, the relationship between aberrations and deformations can be further revealed. The process of IOA is summarized in this article. The principles of four primary Zernike coefficient-solving algorithms (CSAs) were expounded, and the corresponding applications are reviewed in detail, including the least squares method, the Gram–Schmidt orthogonalized method, the Householder transformation, and singular value decomposition (SVD). Artificial neural networks (ANNs) trained for solving a similar overdetermined set of equations are also discussed; an innovative Zernike CSA based on a one-dimensional convolutional neural network (1D-CNN) was proposed, emphasizing its potential for Zernike CSA. The feasibility of the neural network method was verified by conducting experiments on the primary mirror of the front reflection system of a space camera. This review can provide references for the precise optimization of IOA.

Intracavity-squeezed cooling in the three-cavity optomechanical system

Intracavity-squeezed cooling in the three-cavity optomechanical system

Recent advances toward mesoscopic quantum optomechanics

We present a number of approaches, currently in experimental development in our research groups, toward the general problem of macroscopic quantum mechanics, i.e., manifestations of quantum noise and quantum fluctations with macroscopic (engineered and microfabricated by man) mechanical systems. Discussed experiments include a pendulum, a torsion pendulum, a ng-scale phononic-crystal silicon nitride membrane, a μ g-scale quartz resonator, and mg-scale mirrors for optical levitation. We also discuss relevant applications to quantum thermometry with optomechanical systems and the use of squeezed light to probe displacements beyond conventional quantum limits.

Coherent resonant coupling between atoms and a mechanical oscillator mediated by cavity-vacuum fluctuations

We show that an atom can be coupled to a mechanical oscillator via quantum vacuum fluctuations of a cavity field enabling energy transfer processes between them. In a hybrid quantum system consisting of a cavity resonator with a movable mirror and an atom, these processes are dominated by two pair-creation mechanisms: the counterrotating (atom-cavity system) and dynamical Casimir interaction terms (optomechanical system). Because of these two pair-creation mechanisms, the resonant atom-mirror coupling is the result of high-order virtual processes with different transition paths well described in our theoretical framework. We perform a unitary transformation to the atom-mirror system Hamiltonian, exhibiting two kinds of multiple-order transitions of the pair creation. By tuning the frequency of the atom, we show that photon frequency conversion can be realized within a cavity of multiple modes. Furthermore, when involving two atoms coupled to the same mechanical mode, a single vibrating excitation of the mechanical oscillator can be simultaneously absorbed by the two atoms. Considering recent advances in strong and ultrastrong coupling for cavity optomechanics and other systems, we believe our proposals can be implemented using available technology.

Manipulation and enhancement of Einstein-Podolsky-Rosen steering between two mechanical modes generated by two Bogoliubov dissipation pathways

We consider a three-mode optomechanical system in which two mechanical oscillators are independently coupled to a cavity mode driven by two controllable lasers. By controlling the two-tone driving, one can prepare the entanglement and Einstein-Podolsky-Rosen (EPR) steering of two mechanical modes, in which the cavity mode acts as a single reservoir to cool two Bogoliubov modes. We find that the direction of EPR steering can be manipulated effectively by adjusting the damping rates and the thermal noises of two mechanical modes. In addition, we show that the entanglement and EPR steering between two mechanical modes can be enhanced by adding a parametric amplifier (PA) into the cavity. The effects of the strength and phase of the PA on the mechanical entanglement and EPR steering are analyzed and discussed in detail. Meanwhile, the additional PA can also expand the region of the one-way steering and strengthen the robustness of the entanglement and EPR steering against the thermal noise. The present scheme may provide effective resources for quantum information processing.

Single-photon blockade in a hybrid optomechanical system involving two qubits in the presence of phononic number and coherent states

Single-photon blockade in a hybrid optomechanical system involving two qubits in the presence of phononic number and coherent states

Force sensing with an optomechanical system at room temperature

We present an alternative approach to force sensing with optomechanical systems. The operation is based on a nonlinear dynamical mechanism, which locks the mechanical oscillation and the associated cavity field pattern of a system when two external drive tones satisfy a frequency match condition. Under a weak force that adds a slight detuning to the external driving fields, the cavity field will undergo a transition between two locked patterns while the locked mechanical oscillation is well preserved, thus having the small modifications to its sidebands. The force sensing is realized by detecting the intensity changes of the cavity field sidebands in such process. With the currently available optomechanical systems, the sensitivity of force detection can reach the level of attonewton and can be further improved with improved system parameters and longer detection time. One important feature of the applied dynamical scenario is that thermal noise insignificantly affects the cavity field sidebands of the locked states, so that the scheme can work well even at room temperature. This method is hopeful to reduce the difficulty in the practical applications of force sensing.

Steady state quantum statistics of a hybrid optomechanical-ferromagnet system: photon and magnon blockade

Magnon and photon blockade implementation and manipulation have significant practical applications in quantum information processing and quantum metrology due to their tight relations to single-photon and -magnon source devices. In this paper, we propose an experimentally feasible hybrid scheme for the dynamical description of the tripartite interacting system consisting of magnon and phonon modes with photons in an optomechanical system, from which we aim to explore the quantum statistics, as well as the magnon and photon blockade phenomenon. To achieve the purpose, the dissipative solution of the system is obtained with the help of the Lindblad master equation. Via employing the equal-time second-order correlation function and using the steady state solution of the system, the statistics and blockade effects of magnon and photon are analyzed and also their dependence on the parameters involved in the system are discussed. Utilizing feasible parameters, our simulations illustrate that, sub-Poissonian behavior and therefore, blockade of magnon and photon are simultaneously achieved. More importantly, the mentioned blockade effects can be obtained in a range of parameters (and not with specific) which makes our proposal easy to access, experimentally. Considering the above realizations, the introduced scheme opens up a pathway to design single-magnon and -photon generators, which are of crucial importance in advanced quantum science and technologies.

Nanocrystal phononics.

Colloidal nanocrystals are successfully used as nanoscale building blocks for creating hierarchical solids with structures that range from amorphous networks to sophisticated periodic superlattices. Recently, it has been observed that these superlattices exhibit collective vibrations, which stem from the correlated motion of the nanocrystals, with their surface-bound ligands acting as molecular linkers. In this Perspective, we describe the work so far on collective vibrations in nanocrystal solids and their as-of-yet untapped potential for phononic applications. With the ability to engineer vibrations in the hypersonic regime through the choice of nanocrystal and linker composition, as well as by controlling their size, shape and chemical interactions, such superstructures offer new opportunities for phononic crystals, acoustic metamaterials and optomechanical systems.

Strong optomechanical interactions with long-lived fundamental acoustic waves

Traveling-wave optomechanical interactions, known as Brillouin interactions, have now been established as a powerful and versatile resource for photonic sources, sensors, and radio-frequency processors. However, established Brillouin-based interactions with sufficient interaction strengths involve short phonon lifetimes, which critically limit their performance for applications, including radio-frequency filtering and optomechanical storage devices. Here, we investigate a new paradigm of optomechanical interactions with tightly confined fundamental acoustic modes, which enables the unique and desirable combination of high optomechanical coupling, long phonon lifetimes, tunable phonon frequencies, and single-sideband amplification. Using sensitive four-wave mixing spectroscopy controlling for noise and spatial mode coupling, optomechanical interactions with long > --> 2 µ s phonon lifetimes and strong > --> 400 W − 1 m − 1 coupling are observed in a tapered fiber. In addition, we demonstrate novel phonon self-interference effects resulting from the unique combination of an axially varying device geometry with long phonon lifetimes. A generalized theoretical model, in excellent agreement with experiments, is developed with broad applicability to inhomogeneous optomechanical systems.