Optical quantum nondemolition measurement of a single rare earth ion qubit

Mouktik Raha; Songtao Chen; Christopher M Phenicie; Salim Ourari; Alan M Dibos; Jeff D Thompson

doi:10.1038/s41467-020-15138-7

Optical quantum nondemolition measurement of a single rare earth ion qubit

Nat Commun. 2020 Mar 30;11(1):1605. doi: 10.1038/s41467-020-15138-7.

Authors

Mouktik Raha¹, Songtao Chen¹, Christopher M Phenicie¹, Salim Ourari¹, Alan M Dibos^{1

2}, Jeff D Thompson³

Affiliations

¹ Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA.
² Nanoscience and Technology Division, Argonne National Laboratory, Argonne, IL, 60439, USA.
³ Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA. [email protected].

Abstract

Optically-interfaced spins in the solid state are a promising platform for quantum technologies. A crucial component of these systems is high-fidelity, projective measurement of the spin state. Here, we demonstrate single-shot spin readout of a single rare earth ion qubit, Er³⁺, which is attractive for its telecom-wavelength optical transition and compatibility with silicon nanophotonic circuits. In previous work with laser-cooled atoms and ions, and solid-state defects, spin readout is accomplished using fluorescence on an optical cycling transition; however, Er³⁺ and other rare earth ions generally lack strong cycling transitions. We demonstrate that modifying the electromagnetic environment around the ion can increase the strength and cyclicity of the optical transition by several orders of magnitude, enabling single-shot quantum nondemolition readout of the ion's spin with 94.6% fidelity. We use this readout to probe coherent dynamics and relaxation of the spin.