Coherent Semiconductor-Based Superconducting Quantum Circuits*

The recent development of semiconductors with epitaxial superconducting Al contacts offers new approaches to realizing coherent superconducting quantum devices. We have demonstrated superconducting transmon qubits with Josephson junctions based on hybrid superconductor-semiconductor materials [1-2]. These gate tunable transmons (gatemons) have the potential advantage that they can be readily controlled through local electrostatic gating of the junction element. I will discuss progress in improving coherence times and scalability of gatemon qubits. I will also discuss how these hybrid circuits might be used to realize novel qubits that are intrinsically protected against sources of decoherence [3].

[1] T. W. Larsen et al., Physical Review Letters 115, 127001 (2015).
[2] L. Casparis et al., Nature Nanotechnology 13, 915–919 (2018).
[3] T. W. Larsen et al., Physical Review Letters 125, 056801 (2020).