Energy-Tunable Quantum Dot with Minimal Fine Structure Created by Using Simultaneous Electric and Magnetic Fields

TL;DR

This paper demonstrates a method to minimize the fine-structure splitting in quantum dots by applying combined electric and magnetic fields, enabling tunable entangled photon sources with minimal FSS.

Contribution

It introduces a dual tuning approach using electric and magnetic fields to achieve minimal FSS in quantum dots, enhancing entangled photon emission control.

Findings

FSS can be reduced to a minimum value using combined electric and magnetic fields.

A minimum FSS exists in each quantum dot, independent of tuning mechanisms.

FSS tuning spans several meV with a 5-T magnet.

Abstract

The neutral biexciton cascade of single quantum dots is a promising source of entangled photon pairs. The character of the entangled state is determined by the energy difference between the excitonic eigenstates known as fine-structure splitting (FSS). Here we reduce the magnitude of the FSS by simultaneously using two independent tuning mechanisms: in-plane magnetic field and vertical electric field. We observe that there exists a minimum possible FSS in each quantum dot which is independent of these tuning mechanisms. However, with simultaneous application of electric and magnetic fields, we show the FSS can be reduced to its minimum value as the energy of emission is tuned over several meV with a 5-T magnet.