Enhanced photocurrent readout for a quantum dot qubit by bias modulation

TL;DR

This paper introduces a method to enhance photocurrent readout in quantum dot qubits by modulating the bias voltage, improving detection efficiency and tunneling times for better quantum control.

Contribution

It presents a novel bias modulation technique that optimizes photocurrent detection and coherence times in quantum dot qubits, surpassing constant bias methods.

Findings

Achieved 68% detection efficiency with bias modulation.

Extended electron tunneling time to 200 ps from 120 ps.

Extended hole tunneling time to 20 ns from 7 ns.

Abstract

We demonstrate coherent control of a quantum dot exciton using photocurrent detection with a sinusoidal reverse bias. Optical control is performed at low bias, where tunneling-limited coherence times are long. Following this step, the tunneling rates are increased to remove the long-lived hole, achieving a high photocurrent signal. For a detection efficiency of 68%, electron and hole tunneling times during optical control of 200 ps and 20 ns can be achieved, compared to 120 ps and 7 ns for the constant bias case, respectively.