Optical switching remains a key outstanding challenge for scalable fault-tolerant photonic quantum computing due to the trade-off between speed, bandwidth, and loss. Scalable quantum photonics demands all three, to enable high computational clock rates and resource efficient scaling to large systems. We present a cavity-based optical switch that overcomes this limitation, demonstrating 22 ns rise time, insertion loss of 2.4 dB, and 17.5 dB extinction ratio. All-optical control is achieved via phase modulation of a signal field detuned from the near-degenerate two-photon absorption ladder in warm rubidium vapor. The ultimate performance of our switch, combining both speed and efficiency, will find applications in active multiplexing, loop-based quantum memory, and feedforward for quantum error-correction protocols.
@article{arxiv.2508.06255,
title = {Cavity-based optical switching via phase modulation in warm rubidium vapor},
author = {Georgia Booton and Tabijah Wasawo and William O. C. Davis and Cameron McGarry and Kristina R. Rusimova and Alex O. C. Davis and Josh Nunn and Peter J. Mosley},
journal= {arXiv preprint arXiv:2508.06255},
year = {2026}
}