TiN

TiN in numbers

Transition temperature

4.5 K

Made as

film

Nitrogen line

Below 77 K

Why engineers choose TiN

TiN is chosen for two properties that have nothing to do with carrying current. It has a large kinetic inductance, so a resonator made from it can be physically small and still resonate low, which is what a kinetic-inductance detector array needs. And its loss at the single-photon powers a qubit readout works at is low enough to compete with the best niobium surfaces. Its transition temperature moves with nitrogen content and strain, which is unusual on this list: the film can be tuned toward the application rather than accepted as it comes.

Where TiN stops

Tunability is also the exposure. A property set by deposition conditions is a property that belongs to one chamber on one day, and TiN is the standing example of a film whose published numbers are hard to reproduce somewhere else. That is a process-window and interface problem rather than a physics one, which is the class that stops programs quietly.