Optomagnonic continuous-variable quantum teleportation enhanced by non-Gaussian distillation

TL;DR

This work presents the first CV quantum teleportation protocol in optomagnonics, transmitting an input optical state to a remote magnon mode within a YIG sphere coupled to a microwave cavity. To overcome weak intrinsic optomagnonic coupling, it introduces non-Gaussian distillation via single magnon and photon subtraction, yielding enhanced entanglement and higher teleportation fidelity. The protocol supports teleporting coherent, single-photon, squeezed, and cat states, with analytical fidelity expressions showing clear advantages of distillation over Gaussian entanglement. The approach provides a practical route toward magnon-based quantum networks and repeaters, enabling diverse magnonic quantum state preparation through photon-to-magnon teleportation, and outlines pathways for experimental realization. All key components are framed within the Braunstein–Kimble CV teleportation protocol, adapted to the optomagnonic platform with careful treatment of pulse sequences, displacement operations, and readout via the MW cavity.

Abstract

The capability of magnons to coherently couple with various quantum systems makes them an ideal candidate to build hybrid quantum systems. The optomagnonic coupling is essential for constructing a hybrid magnonic quantum network, as the transmission of quantum information among remote quantum nodes must be accomplished using light rather than microwave field. Here we provide an optomagnonic continuous-variable quantum teleportation protocol, which enables the transfer of an input optical state to a remote magnon mode. To overcome the currently relatively weak coupling in the experiment, we introduce non-Gaussian distillation operations to enhance the optomagnonic entanglement and thus the fidelity of the teleportation. An auxiliary microwave cavity is adopted to realize the non-Gaussian and displacement operations on magnons. We show that a series of optical states, such as coherent, single-photon, squeezed and cat states, can be teleported to the magnon mode. The work provides guidance for the experimental realization of magnonic quantum repeaters and quantum networks and a new route to prepare diverse magnonic quantum states exploiting the photon-to-magnon quantum teleportation.

Figures (5)

• Figure 1: (a) Schematic diagram of optomagnonic CV quantum teleportation. A YIG sphere, supporting a magnon mode and two WGMs with different polarizations (i.e., the TM- and TE-polarized modes), is placed inside a MW cavity. A strong optical pulse with duration $\tau_{e}$ is used to pump the TM-polarized WGM to activate the optomagnonic Stokes scattering, yielding entanglement between the magnon mode and TE-polarized Stokes field, which reaches a low-reflectivity beam splitter ($\mathrm{BS}_{0}$) after passing through a polarizer (P). A single photon is subtracted from the Stokes field when the single-photon detector (SPD) clicks at the reflection port of $\mathrm{BS}_{0}$. The single-photon-subtracted Stokes field is then mixed with an input optical state $\rho_{\rm in}$ at a 50:50 beam splitter ($\mathrm{BS}_{1}$). On the other side, a single magnon is also subtracted from the magnon mode by sending a weak pulse with duration $\tau_{s}$ into the MW cavity and conditioned on the detection of a single MW photon in the output port. Alice subsequently performs the homodyne detection (HD) on the two output fields of $\mathrm{BS}_{1}$ to measure a pair of quadratures $X_{1}$ and $Y_{2}$, and she then tells the results to Bob via classical communication. Based on the results ($X_{1}$, $Y_{2}$), Bob implements a displacement operation onto the magnon mode by sending another pulse with duration $\tau_{d}$ into the MW cavity, which completes the teleportation. The final magnon state can be read out by sending one last MW pulse with duration $\tau_{r}$. (b) Time sequence of the optical and MW pulses used in the protocol. The related description is provided in (a). To minimize the influence of dissipation on the magnon state, the total time of all the pulses is assumed to satisfy $\tau_{\rm total}= \tau_{e} + \tau_{s} + \tau_{d} + \tau_{r} \ll \kappa_{m}^{-1}$. (c) Magnon-induced Stokes scattering used for creating the optomagnonic entanglement, i.e., a TMSV state.
• Figure 2: (a) Entanglement $E_{N}$ of non-Gaussian entangled state \ref{['nonGaus']} (dashed line) and TMSV state \ref{['bbbb']} (solid line) versus effective optomagnonic coupling strength $G_{1}$. (b) Magnon-photon joint number distribution of non-Gaussian state \ref{['nonGaus']} and TMSV state \ref{['bbbb']} (inset). We use experimentally feasible parameters: $\kappa_{m}/2\pi=0.5$ MHz Shen25, $\tau_{e}=50$ ns, $\kappa_{1}/2\pi=100$ MHz, $g_{c}/2\pi=4$ MHz, $\kappa_{c}/2\pi=40$ MHz, and $\tau_{s}=4$ ns, which yield $\mathcal{G}_{c}\tau_{s}\approx 0.01$.
• Figure 3: Fidelity $F$ versus the effective optomagnonic coupling strength $G_{1}$ with the shared entangled state being the TMSV state (solid line) or the distilled non-Gaussian state (dashed line) for an initial state being (a) a coherent state $|\beta\rangle$, (b) a single-photon state $|1\rangle$, and (c) a squeezed vacuum state $|\xi\rangle$. (d) Fidelity $F$ versus the squeezing $\xi$ for an initial squeezed state. We take $\xi=1$ in (c), $G_{1}/2\pi=10$ MHz in (d), and $\tau_{d}=10$ ns. The other parameters are the same as in Fig. \ref{['fig2']}.
• Figure 4: Wigner function of (a) the initial cat state, and of the teleported magnon state by sharing (b) the TMSV state or (c) the distilled non-Gaussian state. We take $\alpha_{0}=1.5$, $\varphi=0$, and $G_{1}/2\pi=10$ MHz. The other parameters are the same as in Fig. \ref{['fig3']}.
• Figure 5: Fidelity $F$ exploiting the TMSV state (solid line) or non-Gaussian entangled state (dashed line) versus (a) the optomagnonic coupling strength $G_{1}$ and (b) the amplitude $\alpha_{0}$ (the phase $\varphi$ in the inset) for an initial cat state. The other parameters are the same as in Fig. \ref{['fig4']}.