Non-unity gain minimal disturbance measurement

TL;DR

This paper introduces and experimentally demonstrates an optimal non-unity gain Gaussian measurement scheme that balances information gain and state disturbance for unknown coherent states, advancing quantum measurement techniques.

Contribution

It presents the first experimental realization of an optimal non-unity gain partial measurement scheme with a derived trade-off relation.

Findings

Optimal trade-off between information gain and disturbance established.

Experimental demonstration using linear optics and feed-forward.

Non-unity gain teleportation saturates the trade-off.

Abstract

We propose and experimentally demonstrate an optimal non-unity gain Gaussian scheme for partial measurement of an unknown coherent state that causes minimal disturbance of the state. The information gain and the state disturbance are quantified by the noise added to the measurement outcomes and to the output state, respectively. We derive the optimal trade-off relation between the two noises and we show that the trade-off is saturated by non-unity gain teleportation. Optimal partial measurement is demonstrated experimentally using a linear optics scheme with feed-forward.