Realizing a Circuit Analog of an Optomechanical System with Longitudinally Coupled Superconducting Resonators

TL;DR

This paper demonstrates a superconducting circuit that mimics optomechanical systems by coupling two resonators with different frequencies, enabling exploration of quantum effects in the radio frequency range.

Contribution

A novel superconducting circuit analog of cavity-optomechanical systems with tunable longitudinal coupling between resonators of different frequencies.

Findings

Achieved a coupling strength increase from 15 kHz to 280 kHz.

Embedded a SQUID to control resonance frequency dependence.

Enabled potential quantum optics experiments in radio frequencies.

Abstract

We realize a superconducting circuit analog of the generic cavity-optomechanical Hamiltonian by longitudinally coupling two superconducting resonators, which are an order of magnitude different in frequency. We achieve longitudinal coupling by embedding a superconducting quantum interference device (SQUID) into a high frequency resonator, making its resonance frequency depend on the zero point current fluctuations of a nearby low frequency LC-resonator. By employing sideband drive fields we enhance the intrinsic coupling strength of about 15 kHz up to 280 kHz by controlling the amplitude of the drive field. Our results pave the way towards the exploration of optomechanical effects in a fully superconducting platform and could enable quantum optics experiments with photons in the yet unexplored radio frequency band.