Minimal Entanglement Witness From Electrical Current Correlations

TL;DR

This paper proposes a simple method to detect entanglement between mobile electrons in solid state conductors using only two current correlation measurements, applicable to various states and detector efficiencies.

Contribution

It introduces a minimal entanglement witness based on electrical current correlations that can identify entanglement with fewer measurements than previous methods.

Findings

All entangled pure states can be detected with two measurements.

Maximally entangled states require three measurements for detection.

The method is robust to nonzero detector efficiencies and non-collinear polarization vectors.

Abstract

Despite great efforts, an unambiguous demonstration of entanglement of mobile electrons in solid state conductors is still lacking. Investigating theoretically a generic entangler-detector setup, we here show that a witness of entanglement between two flying electron qubits can be constructed from only two current cross correlation measurements, for any nonzero detector efficiencies and non-collinear polarization vectors. We find that all entangled pure states, but not all mixed ones, can be detected with only two measurements, except the maximally entangled states, which require three. Moreover, detector settings for optimal entanglement witnessing are presented.