Highly tunable exchange-only singlet-only qubit in a GaAs triple quantum dot

TL;DR

This paper proposes a highly tunable singlet-only spin qubit in a GaAs triple quantum dot, leveraging Coulomb interactions and magnetic fields to achieve controllable qubit splitting with enhanced coherence.

Contribution

It introduces a novel implementation of a singlet-only qubit in a GaAs triple quantum dot with tunable energy splitting and demonstrates full electric control and improved coherence.

Findings

Qubit splitting tunable over tens of μeV by magnetic field adjustment

Full exchange-based electric control of the qubit

Enhanced coherence due to singlet-only nature

Abstract

We propose an implementation of a singlet-only spin qubit in a GaAs-based triple quantum dot with a (1,4,1) charge occupation. In the central multi-electron dot, the interplay between Coulomb interaction and an out-of-plane magnetic field creates an energy spectrum with a tunable singlet-triplet splitting, which can be exploited to create a six-particle singlet-only qubit with a qubit splitting that can straightforwardly be tuned over tens of $\mu$eV by adjusting the external magnetic field. We confirm the full exchange-based electric control of the qubit and demonstrate its superior coherence properties due to its singlet-only nature.