DOE OSTI · 3019882
Erbium quantum memory platform with long optical coherence via back-end-of-line deposition on foundry-fabricated photonics
Abstract
Realizing scalable quantum interconnects necessitates the integration of solid-state quantum memories with foundry photonics processes. While prior photonic integration efforts have relied upon specialized, laboratory-scale fabrication techniques, this work demonstrates the monolithic integration of a quantum memory platform with low-loss foundry photonic circuits via back-end-of-line deposition. We deposited thin films of titanium dioxide (TiO 2 ) doped with erbium (Er) onto silicon nitride nanophotonic waveguides and studied Er optical coherence at subkelvin temperatures with photon echo techniques. Furthermore, we suppressed optical dephasing through ex-situ oxygen annealing and optimized measurement conditions, which yielded an optical coherence time of 64 μs (a 5-kHz homogeneous linewidth) and slow spectral diffusion of 27 kHz over 4 ms, results that are comparable to state-of-the-art Er nanophotonic devices. Combined with second-long electron spin lifetimes and demonstrated electrical control of Er emission, our findings establish Er:TiO 2 on foundry photonics as a manufacturable platform for ensemble and single-ion quantum memories.
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Gupta, Shobhit [memQ, Inc, Chicago, IL (United States)] (ORCID:0009000621517318), Pettit, Robert M. [memQ, Inc, Chicago, IL (United States)], Sundaresh, Ananthesh [memQ, Inc, Chicago, IL (United States)] (ORCID:0009000246732816), Niaouris, Vasileios [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:000000015313748X), Deckoff-Jones, Skylar [memQ, Inc, Chicago, IL (United States)], Crowley, Daniel P. [American Institute for Manufacturing Integrated Photonics (AIM Photonics), Albany, NY (United States)], Carpenter, Lewis G. [American Institute for Manufacturing Integrated Photonics (AIM Photonics), Albany, NY (United States)], Dibos, Alan M. [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000159351364), Singh, Manish Kumar [memQ, Inc, Chicago, IL (United States)] (ORCID:0000000221932689), Sullivan, Sean E. [memQ, Inc, Chicago, IL (United States)]. 2025-11-13. Erbium quantum memory platform with long optical coherence via back-end-of-line deposition on foundry-fabricated photonics. https://doi.org/10.1103/xj8y-b6sl
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