Precision Measurement

In quantum metrology, it has been considered for some time whether quantum error correction can be used to enhance precision measurements. Here, the primary challenge is devising codes ad protocols that correct noise while not correcting the unknown signal being sensed. In this collaboration with the Pichler, we identify some promising conditions for leveraging quantum error correction for enhanced sensing, even when signal and noise couple identically to sensor qubits. 

Drum-like membrane resonators are intriguing for precision sensing because their resonance frequencies can be sensitive to a variety of parameters of interest, from mass to thermal radiation. The quest for improved sensitivity in tensioned membranes faces a tradeoff in which a high amplitude of mechanical motion improves signal-to-noise, but too high of a drive (beyond the so-called critical amplitude) introduces nonlinear effects.

In our work published in NanoLetters, we develop an experimentally straightforward method to evade this tradeoff. Using a patterned, trampoline-shaped membrane, we find that dual-mechanical-mode operation can bring these sensors to a thermally-limited frequency stability.  By measuring and correcting for frequency noise arising at high amplitude, we maintain this high stability when operating beyond the linear regime, opening new opportunities for membrane frequency sensing.