Event Details

Individually addressed rare earth ions are a promising platform for quantum information processing. Erbium is particularly attractive as a single photon source and quantum memory for quantum networks, owing to its optical transition at 1.5 um, in the lowest-loss telecom band. A central challenge to utilizing individual rare earth ions is their low photon emission rates, which results from the dipole-forbidden nature of the intra-4f optical transitions. We have demonstrated a solution to this problem by coupling single **Er^{3+}** ion dopants in a **Y_2SiO_5** crystal to a silicon nanophotonic circuit, where a photonic crystal cavity tuned to the ions' resonance enhances the emission rate by nearly three orders of magnitude  [1]. This has enabled the observation of single-photon emission from single **Er^{3+}** ions for the first time. More recently, we have leveraged the strong cavity modification of the spontaneous emission to control the spin selection rules, which enables single-shot quantum nondemolition measurement of the ion's spin with 95% fidelity  [2]. We have measured the spin T1 of single **Er^{3+}** ions for the first time and find that it exceeds 40 seconds. The spin coherence is limited by the nuclear spin bath, and I will discuss two strategies to mitigate this: dynamical decoupling and control of the spin bath, as well as the development of a new host material that has lower abundance of nuclear spins, **TiO_2**  [3]. I will conclude with prospects for creating arrays of strongly interacting **Er^{3+}** spins using ion implantation, with sub-wavelength optical addressing using frequency multiplexing. [1] A. M. Dibos, M. Raha, C. M. Phenicie, and J. D. Thompson, Phys. Rev. Lett. 120, 243601 (2018). [2] M. Raha, S. Chen, C. M. Phenicie, S. Ourari, A. M. Dibos, and J. D. Thompson, Arxiv 1907.09992 (2019). [3] C. M. Phenicie, P. Stevenson, S. Welinski, B. C. Rose, A. T. Asfaw, R. J. Cava, S. A. Lyon, N. P. De Leon, and J. D. Thompson, ArXiv 1909.06304 (2019).