Quantum state transfer via a hybrid solid–optomechanical interface

We propose a scheme to implement quantum state transfer between two distant quantum nodes via a hybrid solid–optomechanical interface. The quantum state is encoded on the native superconducting qubit, and transferred to the microwave photon, then the optical photon successively, which afterwards is transmitted to the remote node by cavity leaking,and finally the quantum state is transferred to the remote superconducting qubit. The high efficiency of the state transfer is achieved by controllable Gaussian pulses sequence and numerically demonstrated with theoretically feasible parameters.Our scheme has the potential to implement unified quantum computing–communication–computing, and high fidelity of the microwave–optics–microwave transfer process of the quantum state.

Coupled quantum molecular cavity optomechanics with surface plasmon enhancement

Cavity optomechanics is applied to study the coupling behavior of interacting molecules in surface plasmon systems driven by two-color laser beams. Different from the traditional force–distance measurement, due to a resonant frequency shift or a peak splitting on the probe spectrum, we have proposed a convenient method to measure the van der Waals force strength and interaction energy via nonlinear spectroscopy. The minimum force value can reach approximately 10^(-15) N, which is 3 to 4 orders of magnitude smaller than the widely applied atomic force microscope(AFM). It is also shown that two adjacent molecules with similar chemical structures and nearly equal vibrational frequencies can be easily distinguished by the splitting of the transparency peak. Based on this coupled optomechanical system, we also conceptually design a tunable optical switch by van der Waals interaction. Our results will provide new approaches for understanding the complex and dynamic interactions inmolecule–plasmon systems.

Enhancement of feasibility of macroscopic quantum superposition state with the quantum Rabi-Stark model

We propose an efficient scheme to generate a macroscopical quantum superposition state with a cavity optomechanical system,which is composed of a quantum Rabi-Stark model coupling to a mechanical oscillator.In a low-energy subspace of the Rabi-Stark model,the dressed states and then the effective Hamiltonian of the system are given.Due to the coupling of the mechanical oscillator and the atom-cavity system,if the initial state of the atom-cavity system is one of the dressed states,the mechanical oscillator will evolve into a corresponding coherent state.Thus,if the initial state of the atom-cavity system is a superposition of two dressed states,a coherent state superposition of the mechanical oscillator can be generated.The quantum coherence and their distinguishable properties of the two coherent states are exhibited by Wigner distribution.We show that the Stark term can enhance significantly the feasibility and quantum coherence of the generated macroscopic quantum superposition state of the oscillator.

High-finesse Fabry-Perot cavities with bidimensional Si_(3)N_(4) photonic-crystal slabs

Light scattering by a two-dimensional photonic-crystal slab(PCS)can result in marked interference effects associated with Fano resonances.Such devices offer appealing alternatives to distributed Bragg reflectors and filters for various applications,such as optical wavelength and polarization filters,reflectors,semiconductor lasers,photodetectors,bio-sensors and non-linear optical components.Suspended PCS also have natural applications in the field of optomechanics,where the mechanical modes of a suspended slab interact via radiation pressure with the optical field of a high-finesse cavity.The reflectivity and transmission properties of a defect-free suspended PCS around normal incidence can be used to couple out-of-plane mechanical modes to an optical field by integrating it in a free-space cavity.Here we demonstrate the successful implementation of a PCS reflector on a high-tensile stress Si_(3)N_(4) nanomembrane.We illustrate the physical process underlying the high reflectivity by measuring the photonic-crystal band diagram.Moreover,we introduce a clear theoretical description of the membrane scattering properties in the presence of optical losses.By embedding the PCS inside a high-finesse cavity,we fully characterize its optical properties.The spectrally,angular-and polarization-resolved measurements demonstrate the wide tunability of the membrane’s reflectivity,from nearly 0 to 99.9470±0.0025%,and show that material absorption is not the main source of optical loss.Moreover,the cavity storage time demonstrated in this work exceeds the mechanical period of low-order mechanical drum modes.This so-called resolved-sideband condition is a prerequisite to achieve quantum control of the mechanical resonator with light.