Determine the maximum optical power sustainable in an optimized package

Determine the maximum optical power that a gap-engineered niobium transmon can withstand in an optimized package with improved optical absorption and readout performance.

Background

The study uses a deliberately reflective copper package that distributes infrared light across the chip and therefore represents a particularly severe quasiparticle-poisoning environment. In a separate experiment, coating the package interior with an absorbing material increased the optical power required to raise the qubit relaxation rate by approximately two orders of magnitude.

That separate device could not be characterized reliably at higher powers because its readout efficiency was too low. Thus, the maximum optical power sustainable by a gap-engineered transmon in an optimized, light-absorbing package remains unresolved.

References

We leave the investigation of the maximum optical power that a gap-engineered transmon qubit can withstand in an optimized package to future work.

— A quasiparticle-protected superconducting qubit  (2610.12227 - Haug et al., 8 Oct 2026) in Appendix, Section “Maximum optical power and compatibility with optically driven devices”