Joint quantum measurements with minimum uncertainty

TL;DR

This paper experimentally tests the fundamental limits of joint quantum measurements of incompatible observables using single photons, employing two methods to estimate measurement uncertainty under realistic conditions.

Contribution

It introduces and compares two idealized uncertainty-estimation methods adapted for experimental conditions to test quantum measurement uncertainty relations.

Findings

Achieved quantum state fidelities up to 0.99998

Approached fundamental measurement uncertainty limits

Validated measurement-uncertainty relations experimentally

Abstract

Quantum physics constrains the accuracy of joint measurements of incompatible observables. Here we test tight measurement-uncertainty relations using single photons. We implement two independent, idealized uncertainty-estimation methods, the 3-state method and the weak-measurement method, and adapt them to realistic experimental conditions. Exceptional quantum state fidelities of up to 0.99998(6) allow us to verge upon the fundamental limits of measurement uncertainty.