Quantum Acoustomechanics with a Micromagnet

Abstract

We theoretically show how to strongly couple the center-of-mass motion of a micromagnet in a harmonic potential to one of its acoustic phononic modes. The coupling is induced by a combination of an oscillating magnetic field gradient and a static homogeneous magnetic field. The former parametrically couples the center-of-mass motion to a magnonic mode while the latter tunes the magnonic mode in resonance with a given acoustic phononic mode. The magnetic fields can be adjusted to either cool the center-of-mass motion to the ground state, or to enter into the strong quantum coupling regime. The center-of-mass can thus be used to probe and manipulate an acoustic mode, thereby opening new possibilities for out-of-equilibrium quantum nanophysics. Our results hold for experimentally feasible parameters and apply to levitated micromagnets as well as micromagnets deposited on a clamped nanomechanical oscillator.

Angular momentum conservation and phonon spin in magnetic insulators

“…Our treatment of angular momentum transfer in spinlattice interactions should be useful in the study of a variety of problems. Of particular interest would be the application to the magnetic nanosystems like cantilevers [51][52][53] and nanoparticles in polymer cavities [54] or levitated in traps [22][23][24][25]. It could also be extended to study the role of the phonon spin in transport phenomena like the spin Seebeck effect [1].…”

“…where Γ (1) αβ and Γ (2) αβ are due to one-magnon one-phonon and two-magnon one-phonon processes respectively, follow from inserting the ansätze (30) and (31) for the magnon and phonon distribution functions into the kinetic equations (24) and (25). Explicitly,…”

“…The phonon Zeeman effect has also been considered [21]. The quantum dynamics of magnetic rigid rotors has been investigated recently in the context of levitated nanoparticles [22][23][24][25]. Very recently ferromagnetic resonance experiments have shown coherent magnon-phonon coupling over millimeter distances [26].…”

Ultralow Mechanical Damping with Meissner-Levitated Ferromagnetic Microparticles

“…Magnetic levitation can be implemented using diamagnetic [32,33] or superconducting particles [27] in external static fields, or ferromagnetic particles above superconductors [34,35]. Interestingly, these systems have been proposed not only for ultrasensitive force and inertial sensing [34,36], but also to test quantum mechanics in currently inaccessible regimes [4], to enable quantum technologies such as quantum magnetomechanics [27] and acoustomechanics [37] and for ultrasensitive magnetometry [11]. In particular, it has been suggested that a levitated micromagnet can overcome the standard quantum limitations to the resolution per unit volume of a magnetometer [11,38].…”

Single-Spin Magnetomechanics with Levitated Micromagnets

“…The combination of high mechanical Q-factor, strong spin-mechanical coupling, and long spin-coherence is key for a range of applications such as magnetometers, accelerometers and gyroscopes [53], where the magnet is the sensor which is read out through the NV-center [4]. Furthermore, it may enable the exploration of new phenomena, including dynamics between a levitated nanomagnet and a single flux vortex [57][58][59], precession of a non-rotating magnet due to its intrinsic spin angular momentum [60], preparation of non-Gaussian quantum states [9], mechanically mediated quantum networks [3,61], detection of dark matter [56], and measuring the magnets internal degrees of freedom [54].…”