Quantum control theory for coupled 2-electron dynamics in quantum dots

TL;DR

This paper develops optimal control strategies for manipulating two-electron states in quantum dots, achieving rapid state transitions with tailored electric pulses that suppress spin dephasing, advancing quantum dot manipulation techniques.

Contribution

It introduces nonperturbative quantum control methods for coupled two-electron quantum dots, significantly improving transition speed and enabling suppression of spin dephasing.

Findings

Optimized THz electric pulses achieve faster state transitions.

Population of specific excited states suppresses spin dephasing.

Control strategies outperform intuitive pulse designs by an order of magnitude.

Abstract

We investigate optimal control strategies for state to state transitions in a model of a quantum dot molecule containing two active strongly interacting electrons. The Schrodinger equation is solved nonperturbatively in conjunction with several quantum control strategies. This results in optimized electric pulses in the THz regime which can populate combinations of states with very short transition times. The speedup compared to intuitively constructed pulses is an order of magnitude. We furthermore make use of optimized pulse control in the simulation of an experimental preparation of the molecular quantum dot system. It is shown that exclusive population of certain excited states leads to a complete suppression of spin dephasing, as was indicated in Nepstad et al. [Phys. Rev. B 77, 125315 (2008)].