Quantum dot nonlinearity through cavity-enhanced feedback with a charge memory

TL;DR

This paper demonstrates that oxide aperture quantum dot micropillar cavities exhibit strong nonlinear effects and hysteresis at extremely low photon levels due to charge trapping, enabling real-time QD dynamics observation and potential new tuning methods.

Contribution

It introduces a charge memory mechanism in cavity QED systems that causes nonlinearities and hysteresis at very low photon intensities, with a validated power-law charging model.

Findings

Strong QD hysteresis at <0.001 intracavity photons

Charge trapping screens electric field, blueshifts QD transition

Real-time observation of QD dynamics

Abstract

In an oxide apertured quantum dot (QD) micropillar cavity-QED system, we found strong QD hysteresis effects and lineshape modifications even at very low intensities corresponding to less than 0.001 intracavity photons. We attribute this to the excitation of charges by the intracavity field; charges that get trapped at the oxide aperture, where they screen the internal electric field and blueshift the QD transition. This in turn strongly modulates light absorption by cavity QED effects, eventually leading to the observed hysteresis and lineshape modifications. The cavity also enables us to observe the QD dynamics in real time, and all experimental data agrees well with a power-law charging model. This effect can serve as a novel tuning mechanism for quantum dots.