Experimental Schmidt Decomposition and Entanglement Detection

TL;DR

This paper presents an experimental method for detecting quantum entanglement in unknown states with minimal measurements, using local measurements and correlation analysis without prior state knowledge.

Contribution

It introduces a novel entanglement detection scheme that does not require shared reference frames or prior state information, utilizing local measurements and a decision tree approach.

Findings

Successfully detected entanglement in various two-qubit states

Verified the method experimentally with high accuracy

Requires fewer measurements than traditional methods

Abstract

We introduce an experimental procedure for the detection of quantum entanglement of an unknown quantum state with as few measurements as possible. The method requires neither a priori knowledge of the state nor a shared reference frame between the observers. The scheme starts with local measurements, possibly supplemented with suitable filtering, that can be regarded as calibration. Consecutive correlation measurements enable detection of the entanglement of the state. We utilize the fact that the calibration stage essentially establishes the Schmidt decomposition for pure states. Alternatively we develop a decision tree which reveals entanglement within few steps. These methods are illustrated and verified experimentally for various two-qubit entangled states.