Determinisitic Writing and Control of the Dark Exciton Spin using Short Single Optical Pulses

TL;DR

This paper demonstrates the deterministic initialization and full optical control of a long-lived dark exciton spin qubit in a quantum dot without external magnetic fields, highlighting its potential for quantum technology applications.

Contribution

It introduces a method to control dark exciton spin qubits using short optical pulses, eliminating the need for magnetic fields and showcasing advantages over other spin qubits.

Findings

Dark exciton forms a long-lived, pure state qubit.

Short optical pulses enable full control of the qubit.

No external magnetic field is required for control.

Abstract

We demonstrate that the quantum dot-confined dark exciton forms a long-lived integer spin solid state qubit which can be deterministically on-demand initiated in a pure state by one optical pulse. Moreover, we show that this qubit can be fully controlled using short optical pulses, which are several orders of magnitude shorter than the life and coherence times of the qubit. Our demonstrations do not require an externally applied magnetic field and they establish that the quantum dot-confined dark exciton forms an excellent solid state matter qubit with some advantages over the half-integer spin qubits such as the confined electron and hole, separately. Since quantum dots are semiconductor nanostructures that allow integration of electronic and photonic components, the dark exciton may have important implications on implementations of quantum technologies consisting of semiconductor qubits.