# Quantum amplification of mechanical oscillator motion

## TL;DR

This paper presents a technique to amplify tiny mechanical displacements below quantum noise limits using squeezing interactions, demonstrated with a trapped-ion oscillator achieving a 17.5 dB sensitivity increase.

## Contribution

It introduces a widely applicable method for amplifying mechanical displacements below quantum fluctuations using orthogonal squeezing interactions.

## Key findings

- Achieved up to 17.5 dB increase in displacement sensitivity.
- Demonstrated the protocol with a trapped-ion mechanical oscillator.
- Validated the amplification method with no added quantum noise.

## Abstract

Detection of the weakest forces in nature and the search for new physics are aided by increasingly sensitive measurements of the motion of mechanical oscillators. However, the attainable knowledge of an oscillator's motion is limited by quantum fluctuations that exist even if the oscillator is in its lowest possible energy state. Here we demonstrate a widely applicable technique for amplifying coherent displacements of a mechanical oscillator with initial magnitudes well below these zero-point fluctuations. When applying two orthogonal "squeezing" interactions before and after a small displacement, the displacement is amplified, ideally with no added quantum noise. We implement this protocol with a trapped-ion mechanical oscillator and measure an increase of up to 17.5(3) decibels in sensitivity to small displacements.