Quantum backaction evading measurements of a silicon nitride membrane resonator

TL;DR

This paper demonstrates quantum backaction evading measurements on a large silicon nitride membrane oscillator using microwave cavity readout, showing that quantum noise can be avoided in quadrature measurements of large objects.

Contribution

It presents the first experimental realization of quantum backaction evasion on a large membrane oscillator with microwave readout.

Findings

Quantum backaction noise can be evaded in large mechanical oscillators.

Successful quadrature measurement of a 0.5 mm silicon nitride membrane.

Demonstrates feasibility of quantum measurement techniques on macroscopic objects.

Abstract

Quantum backaction disturbs the measurement of the position of a mechanical oscillator by introducing additional fluctuations. In a quantum backaction measurement technique, the backaction can be evaded, although at the cost of losing part of the information. In this work, we carry out such a quantum backaction measurement using a large 0.5 mm diameter silicon nitride membrane oscillator with 707 kHz frequency, via a microwave cavity readout. The measurement shows that quantum backaction noise can be evaded in the quadrature measurement of the motion of a large object.