Single rare-earth ions coupled to a dense nuclear spin bath: a challenge and a resource

Nuclear spins coupled to a central spin can be both be challenge and a resource. Interactions between the central spin and the nuclear spins will lead to decoherence of the central qubit. However, nuclear spins can also serve as auxiliary qubits for quantum networking applications.

In our research, we use single ¹⁷¹Yb ions in YVO₄. At zero magnetic field, the ¹⁷¹Yb isotope (S =1/2, I=1/2) forms electron-nuclear hybridized eigenstates and exhibits a clock transition with first-order insensitivity to magnetic fields. As a result, the Yb central spin has a long coherence time even in the presence of a dense deterministic nuclear spin bath; Y (V) has a nuclear spin of I = 1/2 (I = 7/2) with 100% (99.8%) natural abundancy. Previously, control of next-nearest neighbor V spins can be shown [1].

In this presentation, I will discuss our efforts to extend the nuclear spin control using an off-chip drive and understand the noise processes originating from the nuclear spin bath. This work will enable the further exploration of sensing protocols in complex spin environments and quantum state storage in high-dimensional Hilbert spaces.

[1] A. Ruskuc, C.-J. Wu, J. Rochman, J. Choi, and A. Faraon, “Nuclear spin-wave quantum register for a solid-state qubit,” Nature, vol. 602, no. 7897 (2022)