Frequency Conversion: Side-band cooling, state-swapping, and coherent control of mechanical resonators

TL;DR

This paper explores frequency conversion techniques for mechanical resonators, demonstrating ground-state cooling, state-swapping, and coherent control via superconducting oscillators, advancing quantum technology applications.

Contribution

It introduces numerical simulations showing how frequency conversion enables ground-state cooling, state-swapping, and coherent control of mechanical resonators using superconducting oscillators.

Findings

Effective near-perfect state-swapping from superconductor to resonator.

Superconducting oscillator can control amplitude and phase while cooling.

Numerical evidence of ground-state cooling through frequency conversion.

Abstract

Sideband cooling is a technique that potentially allows mechanical resonators to be prepared in their ground states, important for future applications in quantum technologies. Tian has recently shown that side-band cooling can be implemented by modulating the coupling between a nano-resonator and a superconducting oscillator, a process of frequency conversion [L. Tian, PRB 79, 193407 (2009)]. While side-band cooling is usually treated in the steady-state regime, the effective resonant coupling will also generate near perfect state-swapping from the superconductor to the mechanical resonator. We perform numerical simulations of this system, examining the ground-state cooling achieved by the state-swapping. Further, we show that the superconducting oscillator can be used to control the amplitude and phase of the resonator, while simultaneously cooling it, and thus act as a coherent "quantum feedback controller".