Semiconductor quantum dots as an ideal source of polarization entangled photon pairs on-demand: a review

TL;DR

This review discusses how semiconductor quantum dots are promising on-demand sources of polarization-entangled photon pairs, highlighting recent advances that overcome previous limitations and paving the way for quantum technology applications.

Contribution

It summarizes recent experimental progress demonstrating high-quality entanglement from quantum dots and discusses remaining challenges for their use in quantum information systems.

Findings

Quantum dots can produce high-quality entangled photon pairs on-demand.

Recent studies show decoherence effects are not as limiting as previously thought.

Progress has been made towards practical quantum dot-based entangled photon sources.

Abstract

More than 80 years passed since the first publication on entangled quantum states. In this period of time the concept of spookily interacting quantum states became an emerging field of science. After various experiments proving the existence of such non-classical states, visionary ideas were put forward to exploit entanglement in quantum information science and technology. These novel concepts have not yet come out of the experimental stage, mostly because of the lack of suitable, deterministic sources of entangled quantum states. Among many systems under investigation, semiconductor quantum dots are particularly appealing emitters of on-demand, single polarization-entangled photon-pairs. Although, it was originally believed that quantum dots must exhibit a limited degree of entanglement related to numerous decoherence effects present in the solid-state. Recent studies invalidated the premise of unavoidable entanglement degrading effects. We review the relevant experiments which have led to these important discoveries and discuss the remaining challenges for the anticipated quantum technologies.