Curator's Take
AI Commentary
This article demonstrates a practical protocol that uses chiral magnons in a YIG waveguide to shuttle quantum states between distant NV‑center spin qubits while keeping the joint system in a dark state of the magnon bath, thereby sidestepping decoherence from the magnetic environment. By showing that realistic modulation of the NV–magnon coupling can achieve >95 % fidelity over several microns, it adds a concrete building block to the emerging toolbox of magnonic quantum interconnects and complements recent work on magnon‑mediated entanglement and transduction. The result points toward scalable solid‑state networks where spin qubits are linked via nonreciprocal magnon channels, provided that temperature and dephasing constraints can be met in experiment.
— Mark Eatherly
Summary
We propose a protocol where chiral magnons mediate a state transfer between two distant spin qubits. The protocol is implemented by varying the coupling between the spin qubits and the magnons in time, such that an arbitrary state is transferred from one qubit to the other. The modulation of the coupling is performed such that the two-spin-qubit state is kept as a dark state of the magnon bath, bypassing the associated losses. We show that the protocol can be realized on a hybrid system composed of two nitrogen-vacancy (NV) centers coupled to the nonreciprocal and chiral magnon modes of an yttrium iron garnet (YIG) stripe. We propose two methods to achieve the time modulation of the NV-magnon coupling: i) the NV-magnet distance of both NV centers is varied; ii) the external magnetic field and the NV-magnet distance of one NV center are varied. We evaluate the implementability of both methods numerically, including the constraints on the temperature, and the dephasing time and minimal lifetime of the spin qubits required for high-fidelity state transfer. We find that using realistic experimental parameters, a state transfer between NV centers at a distance of several microns can be achieved with a fidelity $\gtrsim 0.95$. Our findings expand the toolbox of magnonics for quantum information purposes.