Proposal for a loophole-free Bell test with electron spins of donors

TL;DR

This paper proposes a practical setup for a loophole-free Bell test using entangled electron spins of phosphorus donors in semiconductors, aiming to close existing experimental loopholes in testing quantum nonlocality.

Contribution

It introduces a feasible experimental scheme for a loophole-free Bell test with electron spins, utilizing homodyne measurements and high-efficiency spin readout methods.

Findings

Potential Bell inequality violation over 37% with 0.99 detection accuracy.

Achievable violation over 18% with 0.95 detection accuracy.

Fast, independent readout of electron spins within 0.7 microseconds.

Abstract

So far, all experimental tests of Bell inequalities which must be satisfied by all local realistic hidden-variable theories and are violated by quantum mechanical predictions have left at least one loophole open. We propose a feasible setup allowing for a loophole-free test of the Bell inequalities. Two electron spin qubits of phosphorus donors in semiconductors in different cavities 300 m apart are entangled through a bright coherent light and postselections using homodyne measurements. The electron spins are then read out randomly and independently by Alice and Bob, respectively, with unity efficiency in less than 0.7$\mu$s by using optically induced spin to charge transduction detected by radio-frequency single electron transistor. A violation of Bell inequality larger than 37% and 18% is achievable provided that the detection accuracy is 0.99 and 0.95, respectively.