Optimal Control of Quantum Rings by Terahertz Laser Pulses

TL;DR

This paper demonstrates a method for complete control of single-electron states in quantum rings using optimized terahertz laser pulses, enabling the development of fast, laser-driven single-gate qubits with potential quantum computing applications.

Contribution

It introduces an optimal control scheme for laser pulses that surpasses conventional methods, facilitating coherent manipulation of quantum-ring states for quantum information processing.

Findings

Optimal control pulses outperform Rabi oscillation methods.

Switching times in the terahertz regime are achievable.

A realistic approach for laser-driven single-gate qubits is proposed.

Abstract

Complete control of single-electron states in a two-dimensional semiconductor quantum-ring model is established, opening a path into coherent laser-driven single-gate qubits. The control scheme is developed in the framework of optimal control theory for laser pulses of two-component polarization. In terms of pulse lengths and target-state occupations, the scheme is shown to be superior to conventional control methods that exploit Rabi oscillations generated by uniform circularly polarized pulses. Current-carrying states in a quantum ring can be used to manipulate a two-level subsystem at the ring center. Combining our results, we propose a realistic approach to construct a laser-driven single-gate qubit that has switching times in the terahertz regime.