A scheme of parametrically enhanced cavity electro-opto-mechanical converter is proposed in this paper, which utilizes Josephson parametric amplifier and optical parametric amplifier. Basic principles of typical cavity electro-opto-mechanical converter and parametrically enhanced version are introduced briefly. We have probed the squeezing and microwave-optical entanglement performance of the scheme with one or both of the amplifiers. The Wigner distribution of the optical output is obtained to analyze the squeezing effect. Meanwhile, quadrature variances and time domain waveforms of output signals are compared and discussed. The results show that microwave-optical entanglement has been enhanced via nonlinear parametric effects no matter when there is one or two amplifiers. However, single mode squeezing only occurs in the cavity which the amplifier is placed in, and this squeezing effect would not transmit to another cavity which hasn’t been amplified. When both amplifiers are introduced simultaneously, each output of cavity electro-opto-mechanical converter is squeezed independently. Our research provides another way to prepare squeezed microwave or optical signal and proves that microwave-optical entanglement can be well enhanced by introducing parametric amplifiers.
A scheme of parametrically enhanced cavity electro-opto-mechanical converter is proposed in this paper, which utilizes Josephson parametric amplifier and optical parametric amplifier. Basic principles of typical cavity electro-opto-mechanical converter and parametrically enhanced version are introduced briefly. We have probed the squeezing and microwave-optical entanglement performance of the scheme with one or both of the amplifiers. The Wigner distribution of the optical output is obtained to analyze the squeezing effect. Meanwhile, quadrature variances and time domain waveforms of output signals are compared and discussed. The results show that microwave-optical entanglement has been enhanced via nonlinear parametric effects no matter when there is one or two amplifiers. However, single mode squeezing only occurs in the cavity which the amplifier is placed in, and this squeezing effect would not transmit to another cavity which hasn’t been amplified. When both amplifiers are introduced simultaneously, each output of cavity electro-opto-mechanical converter is squeezed independently. Our research provides another way to prepare squeezed microwave or optical signal and proves that microwave-optical entanglement can be well enhanced by introducing parametric amplifiers.
Multipartite entanglement is a key resource for quantum information processing and quantum communication. We show that the robust entanglement among four filtered output optical modes can be achieved when there is a nonlinear crystal inside an optomechanical cavity. The optical parametric amplifier (OPA) gives rise to single-mode squeezing of the cavity modes; therefore, the entanglement among four output optical modes can be enhanced remarkably. Furthermore, the degree of quadripartite entanglement is influenced by the nonlinear gain of OPA and bandwidth of the filters. Large entanglement can be obtained by optimizing the filter functions, which is important for utilizing entangled light beams more efficiently in real experiments. This kind of multipartite entanglement will be useful and valuable in the area of quantum communication networks.
Abstract We investigate the effect of a degenerate optical parametric amplifier (OPA) placed inside an optomechanical cavity on the steady-state entanglement of two cavity modes, which jointly interact with a mechanical resonator. Two cavity modes are, respectively, driven at the red and blue sideband associated with the mechanical resonator, which generates entanglement between them in the limit of resolved sideband. The OPA gives rise to single-mode squeezing of the cavity fields, which results in significant improvement of the two-mode entanglement. It is found that an optimal nonlinear gain of the OPA exists, depending on the system temperatures, which yields the maximum entanglement. The improvement is particularly remarkable for the system at cryogenic temperatures.
Abstract We investigate the entanglement phenomena assisted by a distant nono-electro-optomechanical system with two optical parametric amplifiers. The system consists of two optomechanical cavities coupling to two charged mechanical resonators via Coulomb interaction. Under suitable conditions, the movable mirrors and the two distant cavity fields can exhibit entanglement. The entanglement is strongly manipulated by the parametric gain and the Coulomb coupling. Furthermore, because of the introduction of the charged mechanical oscillators, the entanglement between the two cavity modes and between the movable mirrors displays a splitting phenomenon. We also study the squeezing spectrum of the cavity fields. The results reveal that the output squeezing of the two cavity fields is affected by the frequency of the mirror oscillation and the parametric gain.
We present a microwave photon detection scheme based on wavelength conversion in hybrid cavity system (electro-opto-mechanical converter). By converting microwave pulse into optical pulse efficiently, tough microwave photon detection can be switched to convenient optical photon detection. We demonstrate that a theoretical detection efficiency analogous to optical detection efficiency can be reached by selecting proper parameters. Pulse shapes of both wavelengths match well. Furthermore, we enhance the scheme by applying the Josephson parametric amplifier (JPA) and optical parametric amplifier (OPA) in the respective cavity, and we obtain a maximum detection efficiency enhancement of near 41% compared to the non-amplification case.
ABSTRACT In this thesis, we examine the production of quantum entanglement between optical and microwave cavity modes using a mechanical resonator and optical parametric amplifiers (OPAs). The interaction within this tripartite system is analyzed using the linearized quantum Langevin equations of motion and the linearization approximation, allowing us to study the dynamics of quadrature fluctuations in optical, microwave, and mechanical modes. Specifically, we look at the created bipartite entanglement characteristic in the subsystems of OC-MC, OC-MR, and MC-MR in an opto-electromechanical system. The addition of OPAs provides controlled gain and phase, allowing the system to overcome thermal noise and cavity losses, increasing nonclassical correlations. We use logarithmic negativity, Gaussian steering, and quantum discord to evaluate quantum correlations after solving the covariance matrix using the Lyapunov equation. The results demonstrate that variations in the OPAs nonlinear gain, its phase, and the surrounding temperature affect the degree of subsystem entanglement, which occurs close to the red-sideband detuning of the microwave cavity and is strongly depends on both the OPA gain and its phase. This hybrid technology enables long distance quantum state transmission across optical and microwave frequencies, a valuable resource for future quantum networks and quantum information systems. Keywords: optical cavity, microwave cavity, optical parametric amplifier
Quantum entanglement possesses important applications in quantum computation, quantum communication, and quantum precision measurement. It is also an important method to improve the performance of quantum radar and quantum radio navigation. However, the penetration of light wave is poor due to the high frequency, which leads to detecting limitations in bad weather. In this context, quantum entanglement in the microwave domain has been extensively studied, and it is hopeful to overcome the above-mentioned defects in quantum optics. Although the entangled microwave preparation of continuous variable is achievable at present, there exist still some problems such as poor entanglement performance, low entanglement efficiency, complex signal processing and control, which restrict the development of entangled microwave sources. In order to improve the entanglement performance in microwave domain, a squeezing-angle locking scheme based on single photon counting is proposed. First, two Josephson parametric amplifiers (JPAs) are driven respectively by two pump signals to generate two single-mode squeezed states which are uncorrelated to each other. Next, the squeezing angle difference between the two single-mode squeezed states is adjusted to 180°, and then the two signals are mixed in a superconducting 180° hybrid ring coupler for two entangled microwave outputs. The outputs are single photon detected, and the results are sent to the data processor for solution. The squeezing angle difference between the input single-mode squeezed microwaves is estimated by Bayesian criterion and compared with the target value to calculate the error. Finally, the squeezing angle correction information is fed back into the JPA pump to control the squeezing angle of the single-mode squeezed microwave of the JPA output as well as the relative squeezing angle to reach the target value. Thus, the dual-path entangled microwave with the optimal entanglement performance is output. Comparing with the existing entangled microwave preparation schemes, a single photon counter is utilized in the scheme of this paper, which leads to a detection efficiency of 90%. In addition, the Bayesian criterion is used to estimate the output result, and the theoretical precision reaches the quantum Cramer-Rao lower bound. Meanwhile, the introduced noise level and operation difficulty are reduced, which greatly improves the property of dual-path entangled microwave preparation.