Cavity magnon-polariton interface for strong spin-spin coupling

TL;DR

This paper proposes a hybrid quantum system using cavity magnon-polaritons to achieve strong, long-distance spin-spin coupling between solid-state qubits, which is a significant step forward for quantum information processing.

Contribution

It introduces a novel interface utilizing Kerr magnons and cavity-magnon polaritons to enhance and control spin-spin interactions over distance.

Findings

Exponential enhancement of coupling via magnon squeezing.

Approaching critical cavity-magnon polariton condition enables strong spin-spin coupling.

Potential for manipulating remote solid spins in quantum systems.

Abstract

Strong coupling between single qubits is crucial for quantum information science and quantum computation. However, it is still challenged, especially for single solid-state qubit. Here, we propose a hybrid quantum system, consisting of a coplanar waveguide (CPW) resonator weakly coupled to a single nitrogen-vacancy spin in diamond and a yttrium-iron-garnet (YIG) nanosphere holding Kerr magnons, to realize strong long-distance spin-spin coupling. With a strong driving field on magnons, the Kerr effect can squeeze magnons, and {thus the coupling between the CPW resonator and the sequeezed magnons is exponentially enhanced}, which produces two cavity-magnon polaritons, i.e., the high-frequency polariton (HP) and low-frequency polariton (LP). When the enhanced cavity-magnon coupling {approaches} the critical value (i.e., the frequency of the LP becomes zero), the spin is fully decoupled from the HP, while the coupling between the spin and the LP is significantly improved. In the dispersive regime, a strong spin-spin coupling mediated by the LP is achieved with accessible parameters. Our proposal indicates that the critical cavity-magnon polarition is a potential interface to realize strong spin-spin coupling and manipulates remote solid spins.