Probing charge fluctuator correlations using quantum dot pairs

TL;DR

This paper demonstrates how photon correlation measurements from quantum dot pairs can reveal charge fluctuator dynamics and environmental noise characteristics affecting qubit coherence.

Contribution

It introduces a method to detect charge fluctuator correlations via photon emission statistics in quantum dot pairs, expanding tools for studying decoherence mechanisms.

Findings

Photon bunching occurs with common charge environment when driven on resonance.

Photon antibunching occurs with opposite detunings.

Multiple charge fluctuation rates can be distinguished using this technique.

Abstract

We study a pair of quantum dot exciton qubits interacting with a number of fluctuating charges that can induce a Stark shift of both exciton transition energies. We do this by solving the optical master equation using a numerical transfer matrix method. We find that the collective influence of the charge environment on the dots can be detected by measuring the correlation between the photons emitted when each dot is driven independently. Qubits in a common charge environment display photon bunching, if both dots are driven on resonance or if the driving laser detunings have the same sense for both qubits, and antibunching if the laser detunings have in opposite signs. We also show that it is possible to detect several charges fluctuating at different rates using this technique. Our findings expand the possibility of measuring qubit dynamics in order to investigate the fundamental physics of the environmental noise that causes decoherence.