Nonadiabatic quantum control of a semiconductor charge qubit

TL;DR

This paper demonstrates multipulse nonadiabatic quantum control of a single electron charge qubit in a semiconductor, achieving Ramsey fringes and suggesting methods to extend coherence times via charge-echo techniques.

Contribution

It introduces a method for nonadiabatic quantum control of a charge qubit using multipulse sequences and surface gates, with potential for improved coherence.

Findings

Observed Ramsey fringes with T2* ~ 60 ps

Showed control via nonadiabatic voltage pulses

Simulations indicate potential for charge-echo implementation

Abstract

We demonstrate multipulse quantum control of a single electron charge qubit. The qubit is manipulated by applying nonadiabatic voltage pulses to a surface depletion gate and readout is achieved using a quantum point contact charge sensor. We observe Ramsey fringes in the excited state occupation in response to a pi/2 - pi/2 pulse sequence and extract T2* ~ 60 ps away from the charge degeneracy point. Simulations suggest these results may be extended to implement a charge-echo by reducing the interdot tunnel coupling and pulse rise time, thereby increasing the nonadiabaticity of the pulses.