Magnon blockade in a hybrid ferromagnet-superconductor quantum system

Abstract

The implementation of a single magnon level quantum manipulation is one of the fundamental targets in quantum magnetism with a significant practical relevance for precision metrology, quantum information processing, and quantum simulation. Here, we demonstrate theoretically the feasibility of using a hybrid ferromagnetsuperconductor quantum system to prepare a single magnon source based on magnon blockade effects. By numerically solving the quantum master equation, we show that the second-order correlation function of the magnon mode depends crucially on the relation between the qubit-magnon coupling strength and the driving detuning, and simultaneously signatures of the magnon blockade appear only under quite stringent conditions of a cryogenic temperature. In addition to providing perception into the quantum phenomena of magnon, the study of magnon blockade effects will help to develop novel technologies for exploring the undiscovered magnon traits at the quantum level and may find applications in designing single magnon emitters.A fundamental type of light-matter interface, magnetic dipole interaction, based on the cavity magnon-microwave photon system has attracted a lot of attention and progressed enormously over the past decade [1][2][3][4][5][6][7][8][9]. Previous experiments have demonstrated that strong or even ultrastrong coupling between the collective-excitation mode of spin ensembles and microwave photons in the cavity field can be mediated by magnetic dipole interaction because of the extremely high spin density of ferromagnetic materials [3][4][5][6]. Magnon, regarded as the quantized spin wave, is the dynamic intrinsic excitation of the magnetic ordered body [10], which has been the subject of extensive investigations in many fields of research, for instance, cavity optomagnonics [11][12][13], hybrid ferromagnetic-superconducting system [14][15][16][17], and Dirac or Weyl magnons in topological insulators [18][19][20]. Many novel phenomena and important applications, ranging from optical cooling of magnon [21] and magnon-induced high-order sideband generation [22][23][24] to magnon gradient memory [25,26] and observation of topological magnon insulator states [27] have been theoretically or experimentally verified.Recently, the investigation of the quantum characteristics of the magnon-polariton system has fascinated widespread concern and made substantial progress [28][29][30][31][32]. For example, the generations of magnon-photon-phonon entanglement [28] and squeezed magnon-phonon states [31] from the cavity magnomechanics, as well as the steady Bell state generation via magnon-photon coupling [32] have been proposed. However, as a typical pure quantum phenomenon, the magnon blockade is still unexplored. The earliest blockade effect, Coulomb blockade [33][34][35], was proposed by Gorter et al.[36] to explain the abnormal increase in resistance of granular metals with temperature. Subsequently, photon, phonon, and spin blockade effects were gradually discovered in some nonlinear systems [37][38][...

Enhanced entanglement and asymmetric EPR steering between magnons

“…In particular, the coupling between magnons and the microwave cavity photons can easily reach the strong-coupling regime [5][6][7]; even the ultrastrong-coupling regime [10][11][12] leading to cavity magnon polaritons. The photon-magnon polariton provides great opportunities to study many novel phenomena, such as level attraction [13,14], exceptional surface [15], bistability [16], nonreciprocity [17], magnon blockade [18]. Furthermore, hybrid quantum systems based on magnons may pave the way for achieving microwave-tooptical quantum transducers [19], memories [20], magnonbased data processing and computing circuits [21], and ultrasensitive detection [1] in the area of quantum information science and engineering.…”

Accelerated adiabatic passage in cavity magnomechanics

“…( 42) becomes H exp = (1 + γ)H g , which can be diagonalized with the new operators A = (m+b)/ √ 2 and B = (m−b)/ √ 2, similarly to the transformation in Eqs. (11) and (12). The special initial state |Ψ(0) = |N m |0 b = |N 0 could then expand by the eigenstates in Eq.…”

“…They found new avenues for quantum computing [4], quantum communication [5], and quantum sensing [6]. Analog to the cavity quantum electrodynamics (QED) [7] and optomechanics [8], cavity magnomechanics [9] develops rapidly to become a mesoscopic platform for quantum information processing in both theoretical [10][11][12][13] and experimental aspects [14][15][16][17][18][19][20][21]. Active investigations about magnon-based quantum information transfer focus on the coupling between photons and magnons and that between magnons and phonons in the ferrimagnetic material.…”

Magnon Blockade in a PT‐Symmetric‐Like Cavity Magnomechanical System

“…There are two general ideas: (i) the conventional magnon blockade is based on the anharmonicity of the eigenenergy spectrum coming from kinds of nonlinearities; (ii) the unconventional magnon blockade is based on the destructive quantum interference between different excitation paths. Also, magnon blockade has been studied in a hybrid ferromagnet-superconductor quantum system [24]. Many nonlinear optical effects have attracted intense studies and opened up a promising way to study other important optomechanics and magnetomechanics effects based on the intrinsic properties of optical and magnon systems, e.g., optomechanically induced transparency [25] or squeezing [26], entanglement [27] and magnon Kerr effect [28].…”