Fast optical control of a coded qubit in a triple quantum dot

TL;DR

This paper demonstrates rapid, high-fidelity optical control of a three-electron qubit in a triple quantum dot using optimized electric pulses, advancing quantum information processing techniques.

Contribution

It introduces a method for designing low-fluence, time-dependent electric fields for fast qubit manipulation within nanoseconds using optimal control theory.

Findings

High-fidelity qubit state transitions achieved within nanoseconds.

Optimized pulses are compatible with experimentally available field amplitudes.

Simplified sequential transition pulses are effective based on spectral analysis.

Abstract

In this work, we study strategies for the optical control, within the dipole approximation, of a qubit encoded in the three-electron states of a triple quantum dot. The system is described by effective confining potentials, and its electronic structure by the configuration interaction method. Optimal control theory (OCT) was applied to design low-fluence time-dependent electric fields controlling the qubit in times shorter than a nanosecond. The resulting pulses produce transitions between the qubit states for experimentally available field amplitudes with high fidelity. Their frequency spectra are related to transitions to some lower-lying excited states and a simplified pulse based on those sequential transitions is presented. The limitations of an extended Hubbard description for the type of strategy analyzed here are also discussed.