This work presents a computational analysis of a superconducting transmon
qubit design, in which the superconductor-insulator-superconductor (SIS)
Josephson junction is replaced by a co-planar,
superconductor-constriction-superconductor (ScS) junction. For short junctions
having a Kulik-Omelyanchuk current-phase relationship, we find that the ScS
transmon has an improved charge dispersion compared to the SIS transmon, with a
tradeoff of 50% smaller anharmonicity. These calculations provide a framework
for estimating the superconductor material properties and junction dimensions
needed to provide proper ScS transmon operation at typical gigahertz
frequencies.Comment: 8 pages, 8 figure