Ultrafast sequential charge transfer in a double quantum dot

TL;DR

This paper demonstrates the use of optimal control theory to design electric fields that achieve ultrafast, high-fidelity charge transfer in a double quantum dot system, with robustness to experimental constraints.

Contribution

It introduces a method for coherent, sequential charge transfer in quantum dots using optimal control without eigenstate truncation, achieving near-perfect yields.

Findings

Charge transfer yields between 99% and 99.99%.

Optimal fields are robust to frequency filtering.

The scheme enables hundreds of sequential charge localization processes.

Abstract

We use optimal control theory to construct external electric fields which coherently transfer the electronic charge in a double quantum-dot system. Without truncation of the eigenstates we operate on desired superpositions of the states in order to prepare the system to a localized state and to coherently transfer the charge from one well to another. Within a fixed time interval, the optimal processes are shown to occur through several excited states. The obtained yields are generally between 99% and 99.99% depending on the field constraints, and they are not dramatically affected by strict frequency filters which make the fields (e.g., laser pulses) closer to experimental realism. Finally we demonstrate that our scheme provides simple access to hundreds of sequential processes in charge localization while preserving the high fidelity.