Tunable Capacitor For Superconducting Qubits Using an InAs/InGaAs Heterostructure

TL;DR

This paper proposes a gate-tunable superconducting qubit coupler based on an InAs/InGaAs heterostructure, demonstrating high on/off ratios and promising coherence times through detailed simulations, advancing scalable quantum computing hardware.

Contribution

It introduces a novel, low-loss, high-contrast tunable coupler design utilizing a 2D electron gas in an InAs/InGaAs heterostructure, supported by comprehensive numerical analysis.

Findings

Achieves an on/off ratio exceeding tenfold in simulations

Estimates coupler coherence times from microseconds to tens of microseconds

Provides a blueprint for scalable, low-loss quantum couplers

Abstract

Adoption of fast, parametric coupling elements has improved the performance of superconducting qubits, enabling recent demonstrations of quantum advantage in randomized sampling problems. The development of low loss, high contrast couplers is critical for scaling up these systems. We present a blueprint for a gate-tunable coupler realized with a two-dimensional electron gas in an InAs/InGaAs heterostructure. Rigorous numerical simulations of the semiconductor and high frequency electromagnetic behavior of the coupler and microwave circuitry yield an on/off ratio of more than one order of magnitude. We give an estimate of the dielectric-limited loss from the inclusion of the coupler in a two qubit system, with coupler coherences ranging from a few to tens of microseconds.