Magnon heralding in cavity optomagnonics

Abstract

In the emerging field of cavity optomagnonics, photons are coupled coherently to magnons in solidstate systems. These new systems are promising for implementing hybrid quantum technologies. Being able to prepare Fock states in such platforms is an essential step towards the implementation of quantum information schemes. We propose a magnon-heralding protocol to generate a magnon Fock state by detecting an optical cavity photon. Due to the peculiarities of the optomagnonic coupling, the protocol involves two distinct cavity photon modes. Solving the quantum Langevin equations of the coupled system, we show that the temporal scale of the heralding is governed by the magnon-photon cooperativity and derive the requirements for generating high fidelity magnon Fock states. We show that the nonclassical character of the heralded state, which is imprinted in the autocorrelation of an optical "read" mode, is only limited by the magnon lifetime for small enough temperatures. We address the detrimental effects of nonvacuum initial states, showing that high fidelity Fock states can be achieved by actively cooling the system prior to the protocol. * Electronic address: victor.bittencourt@mpl.mpg.de †

Remote magnon entanglement between two massive ferrimagnetic spheres via cavity optomagnonics

“…The magnon entangled state of two ferrimagnetic spheres, which contain more than 10 18 spins and can be distantly separated, is truly a macroscopic quantum state and manifests its nonlocal nature. Our work, along with the earlier studies [44,45,47], show that cavity optomagnonics could become a promising platform for the study of macroscopic quantum phenomena.…”

“…Such a mechanism can be used for the manipulation of magnons, and has been adopted for preparing nonclassical states of magnons. This includes the proposals for cooling the magnons [44], preparing magnon Fock states [45], a magnon laser [46], an optomagnonic Bell test [47], and an opto-microwave entanglement mediated by magnons [48], etc.…”

Quantum network with magnonic and mechanical nodes

“…Owing to the selection rule [52][53][54][55] imposed by the conservation of the angular momenta of WGM photons and magnons, the BLS shows a pronounced asymmetry in the Stokes and anti-Stokes scattering strengths. This asymmetry is the basis for realizing the proposals for preparing macroscopic quantum states of magnons in optomagnonics [56][57][58][59][60][61].…”

Optomagnonics in dispersive media: magnon-photon coupling enhancement at the epsilon-near-zero frequency

“…is the magnetization-dependent permittivity tensor. This expression for u ωc assumes that the frequency of the electromagnetic waves is such that ω c ω m , where ω m is the frequency of the magnetization oscillations (∼ GHz), which allows a rotating wave approximation (a discussion is presented in [31]). Since we are interested in optical frequencies for the electromagnetic field, we do not consider dispersion of the permeability tensor.…”