Time-Domain Two-Magnon Interference Enabled by a Tunable Beamsplitter

Abstract

This letter presents a model system for controllable two-magnon interference in the time domain. This two-magnon interference, i.e., a magnonic analog to the photonic Hong-Ou-Mandel effect, is supported by a tunable magnonic beamsplitter operation formed in a hybrid cavity magnonic system comprising a pair of mutually coupled magnon modes. By applying a time-dependent magnetic field, magnons can be excited independently in each mode and subsequently brought into interaction, shifting from independent to collective oscillations, to realize a controllable magnonic beamsplitter. When the beamsplitter operation is applied to an initially unentangled two-magnon state, a maximally entangled magnonic $N00N$ state with tunable phase sensitivity is produced. These findings suggest that two-magnon interference in hybrid cavity magnonic systems may enable novel quantum metrological devices to study fundamental magnon dynamics and contribute to developing hybrid magnonic quantum computing architectures.

Figures (3)

• Figure 1: Candidate geometries for time-domain magnonic interference. (a) Representative hybrid magnonic platform in which two spatially separated magnon modes (red, blue) are indirectly coupled via an intermediate bosonic channel (gold). (b) Generalized model used in this work, consisting of two magnon modes with tunable frequencies $\omega_1(t)$ and $\omega_2(t)$ mutually coupled by an effective interaction $g$.
• Figure 2: Single-magnon characterization of the temporal magnonic beamsplitter. (a) Time-dependent magnon frequencies $\omega_1(t)$ (blue) and $\omega_2(t)$ (red) are tuned by a magnetic-field pulse, reducing $\Delta\omega$ for a duration $\tau$ (gray). (b) Temporal profile of $\Delta\omega$. (c) Simulated evolution of an $\ket{10}$ state under a balanced TBS pulse to $(\ket{10}+\ket{01})/\sqrt{2}$. Simulation parameters: $\Delta\omega=0$, $g=2\pi\times20$ MHz.
• Figure 3: Controllable generation of maximally entangled magnonic $N00N$ states using a TBS pulse. (a) Simulated time evolution showing coherent transformation from $|11\rangle$ to the entangled state $(|20\rangle + e^{i2\varphi}|02\rangle)/\sqrt{2}$. (b) Output phase $\varphi$ of the $N00N$ state as a function of $\Delta\omega$.