Optical control of coherent interactions between quantum dot electron spins

TL;DR

This paper demonstrates optical control of interactions between electron spins in quantum dots, showing phase shifts and modulations consistent with a Heisenberg-like interaction, advancing quantum gate development.

Contribution

It introduces a method to manipulate and observe coherent spin interactions in quantum dots using pulsed laser techniques, revealing Heisenberg-like coupling effects.

Findings

Observation of spin precession phase shifts

Modulation of spin magnitudes after optical orientation

Evidence for microeV-strength Heisenberg-like interactions

Abstract

Coherent interactions between spins in quantum dots are a key requirement for quantum gates. We have performed pump-probe experiments in which pulsed lasers emitting at different photon energies manipulate two distinct subsets of electron spins within an inhomogeneous InGaAs quantum dot ensemble. The spin dynamics are monitored through their precession about an external magnetic field. These measurements demonstrate spin precession phase shifts and modulations of the magnitude of one subset of oriented spins after optical orientation of the second subset. The observations are consistent with results from a model using a Heisenberg-like interaction with microeV-strength.