arXiv subjects

Zi-Xu Lu

Publications and source records attributed to Zi-Xu Lu.

8 recordsLinked to original sources

arXiv2026

Optomagnonic generation of entangled travelling fields with different polarizations

The optomagnonic coupling between magnons and optical photons is an essential component for building remote quantum networks based on magnonics. Here we show that such a coupling, manifested as the magnon-induced Brillouin light scattering, can be exploited to entangle two propagating optical fields. The protocol employs two pairs of the whispering gallery modes coupled to the same magnon mode in a YIG sphere. In each pair a strong pump field is applied to activate either Stokes or anti-Stokes scattering. Due to the magnon mode involving in the two scattering processes and as a mediation, Stokes and anti-Stokes photons of different polarizations get entangled. The entanglement can be extracted by filtering the travelling output fields centered at the Stokes and anti-Stokes sidebands. Optimal conditions are identified under which strong output entanglement can be achieved.

quant-ph↗

arXiv2026

Quantum Magnonics: Quantum States Generation and Applications

Hybrid systems based on magnons in ferromagnetic materials, such as yttrium iron garnet, have achieved remarkable development in the last decade. These include the coupling of magnons to microwave and optical photons, superconducting qubits, phonons, spins, the center-of-mass motion of a ferromagnet, etc. Here, we review both the experimental and theoretical progress in this field, focusing on the generation of magnonic quantum states and their applications in a broad range of fields. Since the strong coupling is a prerequisite for achieving coherent quantum control of magnons and preparing magnonic quantum states, we start by introducing representative strong-coupling experiments in cavity magnonics, then review a series of protocols for creating various magnonic quantum states, such as Fock, cat, squeezed, and entangled states, and discuss their potential applications in macroscopic quantum studies, quantum information science, quantum sensing, magnonic quantum devices, dark matter detection, and so on. Finally, we summarize the review and give an outlook for the future study of quantum magnonics.

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arXiv2026

Squeezed light in a semiconductor microcavity

Squeezed light is a particularly useful quantum resource, which finds broad applications in quantum information processing, quantum metrology and sensing, and biological measurements. Here we show how to produce squeezed light exploiting the strong exciton-phonon nonlinear interaction in a semiconductor microcavity. The semiconductor microcavity is embedded with a quantum well, which supports both linear and nonlinear interactions among excitons, phonons, and cavity photons. We show that the strong exciton-phonon deformation potential interaction can induce a quadrature-squeezed cavity output field, and further reveal an important role of the exciton-photon coupling in engineering the squeezing spectrum and improving the robustness of the squeezing against thermal noise. Our results indicate that substantial optical squeezing in a broad band, up to tens of gigahertz, can be achieved using currently available parameters.

quant-ph↗

arXiv2026

Magnonic Gottesman-Kitaev-Preskill states

Bosonic quantum error correction encodes a logical qubit in an oscillator, avoiding the hardware overhead of large qubit arrays. Among such encodings, Gottesman-Kitaev-Preskill (GKP) states are paticularly powerful because their phase-space grid structure protects against small displacement errors simultaneously in both conjugate quadratures. Here we provide the first protocol for preparing magnonic GKP states, which involves an ellipsoidal magnetic crystal effectively coupled to a superconducting qubit via a microwave cavity. The geometric anisotropy intrinsically squeezes the magnon mode, while the cavity-mediated qubit control realizes an effective conditional-displacement interaction. We show that two rounds of a conditional-displacement interaction and a qubit projective measurement yield three- and four-component magnonic GKP-like states. We also show how to realize single logical qubit gate operations, such as Pauli, Hadamard and phase gates, completing the logical Pauli basis of the approximate GKP code. Our results establish hybrid magnon-qubit systems as a promising platform for preparing bosonic code states, with applications in magnonic fault-tolerant quantum computation and quantum sensing.

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arXiv2026

Generation of mechanical cat-like states via optomagnomechanics

We propose an optomagnomechanical approach for preparing a cat-like superposition state of mechanical motion. Our protocol consists of two steps and is based on the magnomechanical system where the magnetostrictively induced displacement further couples to an optical cavity mode via radiation pressure. We first prepare a squeezed mechanical state by driving the magnomechanical system with two microwave pulses. We then switch off the microwave drives and send a weak red-detuned optical pulse to the optical cavity to weakly activate the optomechanical anti-Stokes scattering. We show that $k$ phonons can be subtracted from the prepared squeezed thermal state, conditioned on the detection of $k$ anti-Stokes photons from the cavity output field, which prepares the mechanical motion in a cat-like state. The work provides a new avenue for preparing mechanical superposition states by combining opto- and magnomechanics and may find applications in the study of macroscopic quantum states and the test of collapse theories.

quant-ph↗

arXiv2025

Cooling mechanical motion with polaritons

The strong coupling between light and matter gives rise to polaritons. Further coupling polaritons to phonons leads to the formation of hybrid polaromechanical systems. Recent experiments have achieved the strong coupling between polaritons and phonons in two configurations, namely, the magnon-photon-phonon and exciton-photon-phonon systems, which enables the control of mechanical motion via manipulating polaritons. Here, we present a polaromechanical cooling theory and explicitly show how two polaritons can be used to simultaneously cool two mechanical modes. The unique advantage of our protocol lies in the fact that the continuous tunability of the polariton frequencies over a wide range allows for the cooling of any two mechanical modes with their frequency difference falling within this range. We further discuss how to extend the theory to cool multiple mechanical modes. The protocol is designed for cooling mechanical motion in various emerging polaromechanical platforms, such as magnon-, exciton-, and plasmon-polaromechanical systems, which is the first step towards quantum states generation in these hybrid systems.

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arXiv2025

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

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.

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arXiv2025

Preparing magnonic non-Gaussian states by adding a single magnon onto Gaussian states

Quantum magnonics based on YIG spheres provides a new arena for observing macroscopic quantum states. Here we propose to prepare two kinds of non-Gaussian magnonic states by adding a single magnon onto two Gaussian states, namely, coherent and thermal states. We adopt an optomagnonic system of a YIG sphere and use fast optical pulses to weakly activate the magnon-induced Stokes scattering. Conditioned on the detection of a polarized single photon, a single magnon can be added onto an initial Gaussian state. We use a microwave cavity to prepare an initial magnon coherent state and finally read out the generated single-magnon added coherent or thermal state. Both the non-Gaussian states of a magnon mode in a large-size YIG sphere are macroscopic quantum states, which exhibit many nonclassical properties, such as sub-Poissonian statistics, quadrature squeezing, and a negative Wigner function. Further, both states show a smooth transition from a quantum state to a classical state by changing the coherent or thermal magnon excitations and thus can be used for the fundamental study of the quantum-to-classical transition.

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