Design of a W-band Superconducting Kinetic Inductance Qubit (Kineticon).

Superconducting qubits are widely used in quantum computing research and industry. We describe a superconducting kinetic inductance qubit (Kineticon) operating at W-band frequencies with a nonlinear nanowire section that provides the anharmonicity required for two distinct quantum energy states. Operating the qubits at higher frequencies relaxes the dilution refrigerator temperature requirements for these devices and paves the path for multiplexing a large number of qubits. Millimeter-wave operation requires superconductors with relatively high Tc, which implies high gap frequency, 2$\Delta$/h, beyond which photons break Cooper pairs. For example, NbTiN with Tc=16K has a gap frequency near 1.4 THz, which is much higher than that of aluminum (90 GHz), allowing for operation throughout the millimeter-wave band. Here we describe a design and simulation of a W-band Kineticon qubit embedded in a 3-D cavity.