All-optical switch at the two-photon limit

As part of my Marie-Curie Action TEBLa, I explore the properties of a photonic system on a lattice.

All-optical devices hold potential for transforming data transmission and processing by offering faster speeds and lower power consumption compared to electronic counterparts without the need for signal conversion. Inspired by this, we propose a switch operation mechanism based on single-particle localization, which also plays a role in flat band physics with non-trivial quantum geometry and Aharonov-Bohm cages. The device is designed in such a way that a “signal photon” is trapped in a localized state but can delocalize due to the interaction with a second one, the “control photon”. Most importantly the switching is successful for an arbitrarily small interaction strength, and we demonstrate that the switching time is optimized when the interaction is comparable to the single-photon hopping. In particular, as both the control and signal consist of single photons, our research proposes a device that works in the purely quantum mechanical limit, differently from existing all-optical switches, which often work with either a single photon for the control or the signal, but rarely with both. This work has been published open access on Physical Review Research.

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