Towards quantum networks and strongly interacting spin systems with rare earth ions
Prof. Jeff Thompson, Princeton University
Leuchs-Russell Auditorium, A.1.500, Staudtstr. 2
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 µm, 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 Er3+ ion dopants in a Y2SiO5 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 . This has enabled the observation of single-photon emission from single Er3+ 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 . We have measured the spin T1 of single Er3+ ions for the first time and find that it exceeds 40 seconds. T2 reaches 100 µs, 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 materials with lower abundance of nuclear spins, such as TiO2 . I will conclude with prospects for creating arrays of strongly interacting Er3+ spins using ion implantation, with sub-wavelength optical addressing using frequency multiplexing. Using this strategy, we have recently demonstrated simultaneous initialization, measurement and control of two ions in a single optical mode .
 A. M. Dibos, M. Raha, C. M. Phenicie, and J. D. Thompson, Phys. Rev. Lett. 120, 243601 (2018).
 M. Raha, S. Chen, C. M. Phenicie, S. Ourari, A. M. Dibos, and J. D. Thompson, arxiv 1907.09992 (2019).
 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).
 S. Chen, M. Raha, et al, manuscript in preparation (2019).