Independent, extensible control of same-frequency superconducting qubits by selective broadcasting

TL;DR

This paper presents a scalable control method for same-frequency superconducting qubits using a vector switch matrix to broadcast and tailor pulses, enabling independent gate operations with minimal leakage, suitable for large quantum processors.

Contribution

It introduces a selective broadcasting control strategy with five pulse primitives for independent, simultaneous qubit gates, improving hardware efficiency in quantum computing.

Findings

Achieved surface-code-compatible single-qubit gate error thresholds.

Demonstrated independent, simultaneous Clifford gates on multiple qubits.

Validated control strategy with randomized benchmarking.

Abstract

A critical ingredient for realizing large-scale quantum information processors will be the ability to make economical use of qubit control hardware. We demonstrate an extensible strategy for reusing control hardware on same-frequency transmon qubits in a circuit QED chip with surface-code-compatible connectivity. A vector switch matrix enables selective broadcasting of input pulses to multiple transmons with individual tailoring of pulse quadratures for each, as required to minimize the effects of leakage on weakly anharmonic qubits. Using randomized benchmarking, we compare multiple broadcasting strategies that each pass the surface-code error threshold for single-qubit gates. In particular, we introduce a selective-broadcasting control strategy using five pulse primitives, which allows independent, simultaneous Clifford gates on arbitrary numbers of qubits.