Tunable Capacitor For Superconducting Qubits Using an InAs/InGaAs Heterostructure*

Adoption of fast, parametric coupling elements has improved the performance of superconducting qubits, enabling recent demonstrations of a 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. Our numerical simulations yield an on/off ratio of over two orders of magnitude. We give an estimate of the dielectric-limited loss from the inclusion of the coupler in a two qubit system.