Simultaneous Operations in a Two-Dimensional Array of Singlet-Triplet Qubits

TL;DR

This paper demonstrates simultaneous multi-qubit operations and measurements in a 2D array of singlet-triplet qubits, advancing scalable quantum computing with semiconductor spin qubits.

Contribution

It introduces a 2x2 qubit array with integrated multiqubit operations, measurements, and a tunable interqubit link, showing progress towards scalable quantum processors.

Findings

Successful simultaneous coherent operations and measurements in a 2x2 qubit array.

Implementation of a tunable interqubit link via a multielectron quantum dot.

Demonstration of coherent spin exchange between qubits.

Abstract

In many physical approaches to quantum computation, error-correction schemes assume the ability to form two-dimensional qubit arrays with nearest-neighbor couplings and parallel operations at multiple qubit sites. While semiconductor spin qubits exhibit long coherence times relative to their operation speed and single-qubit fidelities above error correction thresholds, multiqubit operations in two-dimensional arrays have been limited by fabrication, operation, and readout challenges. We present a two-by-two array of four singlet-triplet qubits in gallium arsenide and show simultaneous coherent operations and four-qubit measurements via exchange oscillations and frequency-multiplexed single-shot measurements. A larger multielectron quantum dot is fabricated in the center of the array as a tunable interqubit link, which we utilize to demonstrate coherent spin exchange with selected qubits. Our techniques are extensible to other materials, indicating a path towards quantum processors with gate-controlled spin qubits.