Fast Optical Switching for Quantum Information

Fast, low-loss optical switches are a key technology in facilitating fundamental applications such as high efficiency single-photon generation and quantum routing. Additionally, fast switches form an integral component in protocols such as time-bin encoding and long-distance entanglement swapping for quantum communication, and also enable the efficient creation of exotic photonic states for quantum metrology purposes. Electro-optic (EO) switching via the Pockels effect in bulk crystals is low loss but slow (up to ~10 MHz) due to kilovolt-level voltage demands. On-chip EO modulators operate in the few-volt regime (enabling GHz switching rates) but suffer from high insertion losses. An elegant alternative that can attain both low loss and up to THz switching rates is an all-optical approach that utilizes cross-phase modulation of a signal field by a pump field in an optical fiber. The effectiveness of this technique relies on the polarization of the pump being maintained during the pump-signal interaction, which can be implemented by using two equal-length segments of orthogonally-oriented polarization-maintaining fiber. Here, we present progress towards realizing such a device for telecom-wavelength single photons.