37 research outputs found
Measurement-Induced Long-Distance Entanglement of Superconducting Qubits using Optomechanical Transducers
Although superconducting systems provide a promising platform for quantum
computing, their networking poses a challenge as they cannot be interfaced to
light---the medium used to send quantum signals through channels at room
temperature. We show that mechanical oscillators can mediated such coupling and
light can be used to measure the joint state of two distant qubits. The
measurement provides information on the total spin of the two qubits such that
entangled qubit states can be postselected. Entanglement generation is possible
without ground-state cooling of the mechanical oscillators for systems with
optomechanical cooperativity moderately larger than unity; in addition, our
setup tolerates a substantial transmission loss. The approach is scalable to
generation of multipartite entanglement and represents a crucial step towards
quantum networks with superconducting circuits.Comment: Updated figures, close to published versio
Tutorial: Nonlinear magnonics
Nonlinear magnonics studies the nonlinear interaction between magnons and
other physical platforms (phonon, photon, qubit, spin texture) to generate
novel magnon states for information processing. In this tutorial, we first
introduce the nonlinear interactions of magnons in pure magnetic systems and
hybrid magnon-phonon and magnon-photon systems. Then we show how these
nonlinear interactions can generate exotic magnonic phenomena. In the classical
regime, we will cover the parametric excitation of magnons, bistability and
multistability, and the magnonic frequency comb. In the quantum regime, we will
discuss the single magnon state, Schr\"{o}dinger cat state and the entanglement
and quantum steering among magnons, photons and phonons. The applications of
the hybrid magnonics systems in quantum transducer and sensing will also be
presented. Finally, we outlook the future development direction of nonlinear
magnonics.Comment: 50 pages, 26 figure
Observation of strong coupling between a mechanical oscillator and a cavity-magnon polariton
Cavity magnomechanics (CMM) is an emerging field and has received much
attention in the past decade. It deals with coherent couplings among microwave
cavity photons, magnons and vibration phonons. So far, all previous CMM
experiments have been operated in the weak-coupling regime. This considerably
limits prospective various applications of the system. Here, we demonstrate the
CMM system in the strong-coupling regime and observe the associated normal-mode
splitting. In this regime, the mechanical oscillator is strongly coupled to a
cavity-magnon polariton that is formed by strongly coupled cavity photons and
magnons, and the polariton-mechanics cooperativity reaches , which
is improved by three orders of magnitude than previous CMM experiments. The
system is then in the triple-strong-coupling regime and the normal modes of the
system are the hybridization of microwave photons, magnons and phonons. This is
achieved by significantly reducing the linewidth of the polariton mode using
coherent perfect absorption and the linewidth is reduced by four orders of
magnitude. The work paves the way towards full quantum control of phonons,
photons and magnons, and provides a new platform for the study of rich
strong-coupling effects in multipartite hybrid systems