Quantum interference between three two-spin states in a double quantum dot

TL;DR

This paper experimentally confirms quantum interference between different two-spin states in a double quantum dot, revealing conditions for interference and differences in coherence times of qubit types.

Contribution

It provides experimental validation and modeling of quantum interference between singlet and triplet states, highlighting the conditions and coherence properties of these qubits.

Findings

Interference primarily affects the singlet state occupation.

S/T0 qubit exhibits longer coherence time than S/T+ qubit.

Conditions for quantum interference are identified.

Abstract

Qubits based on the singlet (S) and the triplet (T0, T+) states in double quantum dots have been demonstrated in separate experiments. It has been recently proposed theoretically that under certain conditions a quantum interference could occur from the interplay between these two qubit species. Here we report experiments and modeling which confirm these theoretical predictions and identify the conditions under which this interference occurs. Density matrix calculations show that the interference pattern manifests primarily via the occupation of the common singlet state. The S/T0 qubit is found to have a much longer coherence time as compared to the S/T+ qubit.