Interlaced Dynamical Decoupling and Coherent Operation of a Singlet-Triplet Qubit

TL;DR

This paper demonstrates enhanced coherence of a singlet-triplet qubit using interlaced dynamical decoupling sequences, comparing various protocols to mitigate dephasing effects caused by noise and hyperfine interactions.

Contribution

It introduces an experimental method of interlacing qubit rotations with dynamical decoupling sequences to improve coherence recovery in singlet-triplet qubits.

Findings

CP and CDD sequences achieve T2 ~ 80 microseconds.

Interlaced sequences effectively mitigate dephasing from hyperfine interactions.

Performance of different dynamical decoupling protocols is comparable under experimental conditions.

Abstract

We experimentally demonstrate coherence recovery of singlet-triplet superpositions by interlacing qubit rotations between Carr-Purcell (CP) echo sequences. We then compare performance of Hahn, CP, concatenated dynamical decoupling (CDD) and Uhrig dynamical decoupling (UDD) for singlet recovery. In the present case, where gate noise and drift combined with spatially varying hyperfine coupling contribute significantly to dephasing, and pulses have limited bandwidth, CP and CDD yield comparable results, with T2 ~ 80 microseconds.