Charge-noise tolerant exchange gates of singlet-triplet qubits in asymmetric double quantum dots

TL;DR

This paper proposes asymmetric double quantum dot singlet-triplet qubits that operate in charge noise-insensitive regions, enhancing qubit resilience by controlling exchange interactions in larger dots, with potential for improved quantum computing stability.

Contribution

Introduction of asymmetric double quantum dot systems enabling exchange gates with controllable splitting in charge noise-resistant regions.

Findings

Exchange gates can be operated in charge noise-insensitive regions.

Asymmetric dots allow control of exchange splitting via magnetic fields.

Enhanced qubit resilience to charge decoherence.

Abstract

In the semi-conductor double quantum dot singlet-triplet qubit architecture, the decoherence caused by the qubit's charge environment poses a serious obstacle in the way towards large scale quantum computing. The effects of the charge decoherence can be mitigated by operating the qubit in the so called sweet spot regions where it is insensitive to electrical noise. In this paper, we propose singlet-triplet qubits based on two quantum dots of different sizes. Such asymmetric double dot systems allow the implementation of exchange gates with controllable exchange splitting $J$ operated in the doubly occupied charge region of the larger dot, where the qubit has high resilience to charge noise. In the larger dot, $J$ can be quenched to a value smaller than the intra-dot tunneling using magnetic fields, while the smaller dot and its larger splitting can be used in the projective readout of the qubit.