# Weak value measurement with an incoherent measuring device

## TL;DR

This paper extends the weak value measurement framework to incoherent, mixed-state measuring devices and demonstrates its effectiveness through optical experiments with pseudo-thermal light, showing robustness against decoherence.

## Contribution

It generalizes weak measurement theory to include mixed states of the measuring device and provides an experimental demonstration using incoherent light.

## Key findings

- Incoherent pointers can still enable amplified detection.
- Weak measurements are robust against partial decoherence.
- Experimental validation with pseudo-thermal light supports theoretical predictions.

## Abstract

In the Aharonov-Albert-Vaidman (AAV) weak measurement, it is assumed that the measuring device or the pointer is in a quantum mechanical pure state. In reality, however, it is often not the case. In this paper, we generalize the AAV weak measurement scheme to include more generalized situations in which the measuring device is in a mixed state. We also report an optical implementation of the weak value measurement in which the incoherent pointer is realized with the pseudo-thermal light. The theoretical and experimental results show that the measuring device under the influence of partial decoherence could still be used for amplified detection of minute physical changes and are applicable for implementing the weak value measurement for massive particles.