# State preparation and tomography of a nanomechanical resonator with fast light pulses

## TL;DR

This paper demonstrates high-precision pulsed optomechanical measurements on a cryogenic nanomechanical resonator, enabling state preparation and tomography close to the quantum regime, with implications for quantum sensing and state control.

## Contribution

The work introduces a method for pulsed measurement and state tomography of a nanomechanical resonator with record precision near the quantum limit, utilizing large photon-phonon coupling.

## Key findings

- Achieved a single-pulse measurement imprecision of 9 times the zero-point amplitude.
- Prepared thermally squeezed and purified mechanical states.
- Showed how decoherence affects the growth of the quantum state over time.

## Abstract

Pulsed optomechanical measurements enable squeezing, non-classical state creation and backaction-free sensing. We demonstrate pulsed measurement of a cryogenic nanomechanical resonator with record precision close to the quantum regime. We use these to prepare thermally squeezed and purified conditional mechanical states, and to perform full state tomography. These demonstrations exploit large photon-phonon coupling in a nanophotonic cavity to reach a single-pulse imprecision of 9 times the mechanical zero-point amplitude $x_\mathrm{zpf}$. We study the effect of other mechanical modes which limit the conditional state width to 58 $x_\mathrm{zpf}$, and show how decoherence causes the state to grow in time.