Qubit-qudit entanglement transfer in defect centers with high-spin nuclei

TL;DR

This paper presents a scheme for transferring entanglement from electron spins to long-lived nuclear spin qudits in defect centers, enabling high-dimensional quantum memory with potential applications in quantum networks.

Contribution

It introduces a method to transfer entanglement to nuclear spin qudits of arbitrary dimension using hyperfine interactions, including deterministic generation of maximal entanglement for dimensions that are powers of two.

Findings

Entanglement transfer is facilitated by the Ising component of hyperfine interaction.

Maximal entanglement can be generated deterministically for qudit dimensions that are powers of two.

The scheme is applicable to systems like the $^{73}$Ge germanium vacancy in diamond.

Abstract

We propose a scheme for accumulating entanglement between long-lived qudits provided by central nuclear spins of defect centers. Assuming a generic setting, the electron spin of each node acts as the communication qubit and may be entangled with other nodes, e.g., through a spin-photon interface. The generally available Ising component of the hyperfine interaction is shown to facilitate repeated entanglement transfer onto memory qudits of arbitrary dimension $d\le 2I+1$ with $I$ the nuclear spin quantum number. When $d$ is set to an integer power of two, maximal entanglement can be generated deterministically and without intermittent driving of nuclear spins. The scheme is applicable to several candidate systems, including the $^{73}$Ge germanium vacancy in diamond.