Photonic chip-based scalable switching of single photons from a trapped ion*

Trapped ions are excellent candidates for long-distance quantum networks because of their long qubit coherence times, ability to generate photons entangled with the ion’s qubit states, and high-fidelity single- and two-qubit gates [1,2]. To establish reconfigurable quantum networks, it is advantageous to route single photons from trapped ions using photonic integrated circuits [3]. However, most trapped ions emit photons in the ultra-violet and visible wavelength regime, making them incompatible with present-day photonic foundries. In this work, we show the on-demand routing of single photons emitted from a trapped barium ion, using a foundry-fabricated silicon-nitride photonic integrated circuit [4].  We use quantum frequency conversion to generate C-band telecom single photons from barium ions [5], then couple these photons into a silicon nitride waveguide via an edge coupler. We then route the photons into different output ports of a Mach-Zehnder interferometer using an electrical signal. These results will enable a new generation of compact and reconfigurable integrated photonic devices that can serve as efficient quantum interconnects for quantum computers and sensors.

[1] C. D. Bruzewicz et al.,  Appl. Phys. Rev.6, 21314 (2019).

[2] J. D. Siverns et al., Applied optics 56,  222-230 (2017).

[3] C. Monroe and J. Kim,  Science. 339, 1164–1169 (2013).

[4] U. Saha et al. manuscript in preparation. 

[5] J. Hannegan et al., Appl. Phys. Lett. 119, 084001 (2021).