The entanglement beam splitter: a quantum-dot spin in a double-sided optical microcavity

TL;DR

This paper introduces an entanglement beam splitter using a quantum-dot spin in a double-sided microcavity, capable of efficiently generating various entangled states and performing quantum measurements, advancing quantum information processing.

Contribution

The proposed device uniquely combines high fidelity and efficiency in splitting photon-spin states into entangled states, robust against quantum dot imperfections.

Findings

Achieves near 100% transmission and reflection fidelity.

Can generate photon-photon and spin-spin entanglement deterministically.

Enables single-shot quantum non-demolition measurement of a single spin.

Abstract

We propose an entanglement beam splitter (EBS) using a quantum-dot spin in a double-sided optical microcavity. In contrast to the conventional optical beam splitter, the EBS can directly split a photon-spin product state into two constituent entangled states via transmission and reflection with high fidelity and high efficiency (up to 100 percent). This device is based on giant optical circular birefringence induced by a single spin as a result of cavity quantum electrodynamics and the spin selection rule of trion transition (Pauli blocking). The EBS is robust and it is immune to the fine structure splitting in a realistic quantum dot. This quantum device can be used for deterministically creating photon-spin, photon-photon and spin-spin entanglement as well as a single-shot quantum non-demolition measurement of a single spin. Therefore, the EBS can find wide applications in quantum information science and technology.