Spatially Adiabatic Frequency Conversion in Optoelectromechanical Arrays

Abstract

Faithful conversion of quantum signals between microwave and optical frequency domains is crucial for building quantum networks based on superconducting circuits. Optoelectromechanical systems, in which microwave and optical cavity modes are coupled to a common mechanical oscillator, are a promising route towards this goal. In these systems, efficient, low-noise conversion is possible using a mechanically dark mode of the fields, but the conversion bandwidth is limited to a fraction of the cavity linewidth. Here, we show that an array of optoelectromechanical transducers can overcome this limitation and reach a bandwidth that is larger than the cavity linewidth. The coupling rates are varied in space throughout the array so that the mechanically dark mode of the propagating fields adiabatically changes from microwave to optical or vice versa. This strategy also leads to significantly reduced thermal noise with the collective optomechanical cooperativity being the relevant figure of merit. Finally, we demonstrate that the bandwidth enhancement is, surprisingly, largest for small arrays; this feature makes our scheme particularly attractive for state-of-the-art experimental setups.

Electrooptomechanical Equivalent Circuits for Quantum Transduction

“…having made use of the properties Q * e,− (Ω) = Q e,+ (−Ω) [Eqs. (36,53)] and Z * m,eff (Ω) = Z m,eff (−Ω). The scattering relation (56) fully characterizes the linearized interaction of the system and thus contains, e.g., all of the physical effects familiar from the analogous setup in linearized optomechanics: e.g., dynamical back-action on the mechanical mode ("optical spring effect") [24], Optomechanically Induced Transparency [92], and classical noise squashing [93].…”

“…where the optical susceptibility functions are defined in analogy to their electrical counterparts (53),…”

“…(98), assuming red-detuned driving for both the optical and electrical subsystemsω LC − ω d = Ω m =ω cav − ω l . The current response of interest I o,+ depends on the susceptibility functions (53,97), which at the mechanical peak take the values…”

“…Hence both optomechanics and electromechanics are mature research directions offering quantum-level operation. By combining the two, they would therefore offer a promising platform for quantum transduction between electrical and optical frequencies [49][50][51][52][53] allowing loss-and noiseless conversion of quantum states, but also the generation of, e.g., two-mode squeezed hybrid states of light and microwaves for continuous-variable teleportation [54] and entanglement between distant superconducting qubits by transducer-mediated interaction with a common propagating optical field [55]. In fact, optomechanical interfaces suitable for integration with electrical circuits have already been devised [56][57][58][59][60][61][62][63][64][65][66][67][68].…”

Optimal Control for Robust Photon State Transfer in Optomechanical Systems

“…Further, for the general case where two parametric errors exist simultaneously, we establish that there is a set of optimization parameters enabling the transfer fidelity insusceptible at 10 −3 level within large error range. Especially, since the model studied is quite generic, our protocol is not limited and could be applied to extensive quantum systems, in particular the hybrid opto‐electro‐mechanical (OEM) system, [ 68–80 ] for which faithful microwave‐to‐optical conversion is promising to serve as hybrid transducers or converters in quantum information networks. As an example, we discuss briefly the applicability of the proposed optimization scheme in a typical OEM system.…”