254 research outputs found
Quantum Information at the Interface of Light with Atomic Ensembles and Micromechanical Oscillators
This article reviews recent research towards a universal light-matter
interface. Such an interface is an important prerequisite for long distance
quantum communication, entanglement assisted sensing and measurement, as well
as for scalable photonic quantum computation. We review the developments in
light-matter interfaces based on room temperature atomic vapors interacting
with propagating pulses via the Faraday effect. This interaction has long been
used as a tool for quantum nondemolition detections of atomic spins via light.
It was discovered recently that this type of light-matter interaction can
actually be tuned to realize more general dynamics, enabling better performance
of the light-matter interface as well as rendering tasks possible, which were
before thought to be impractical. This includes the realization of improved
entanglement assisted and backaction evading magnetometry approaching the
Quantum Cramer-Rao limit, quantum memory for squeezed states of light and the
dissipative generation of entanglement. A separate, but related, experiment on
entanglement assisted cold atom clock showing the Heisenberg scaling of
precision is described. We also review a possible interface between collective
atomic spins with nano- or micromechanical oscillators, providing a link
between atomic and solid state physics approaches towards quantum information
processing
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
Coupling ultracold atoms to mechanical oscillators
In this article we discuss and compare different ways to engineer an
interface between ultracold atoms and micro- and nanomechanical oscillators. We
start by analyzing a direct mechanical coupling of a single atom or ion to a
mechanical oscillator and show that the very different masses of the two
systems place a limit on the achievable coupling constant in this scheme. We
then discuss several promising strategies for enhancing the coupling:
collective enhancement by using a large number of atoms in an optical lattice
in free space, coupling schemes based on high-finesse optical cavities, and
coupling to atomic internal states. Throughout the manuscript we discuss both
theoretical proposals and first experimental implementations.Comment: 19 pages, 9 figure
Hybrid Mechanical Systems
We discuss hybrid systems in which a mechanical oscillator is coupled to
another (microscopic) quantum system, such as trapped atoms or ions,
solid-state spin qubits, or superconducting devices. We summarize and compare
different coupling schemes and describe first experimental implementations.
Hybrid mechanical systems enable new approaches to quantum control of
mechanical objects, precision sensing, and quantum information processing.Comment: To cite this review, please refer to the published book chapter (see
Journal-ref and DOI). This v2 corresponds to the published versio
From Cavity Electromechanics to Cavity Optomechanics
We present an overview of experimental work to embed high-Q mesoscopic
mechanical oscillators in microwave and optical cavities. Based upon recent
progress, the prospect for a broad field of "cavity quantum mechanics" is very
real. These systems introduce mesoscopic mechanical oscillators as a new
quantum resource and also inherently couple their motion to photons throughout
the electromagnetic spectrum.Comment: 8 pages, 6 figures, ICAP proceedings submissio
Multimode optomechanical system in the quantum regime
We realise a simple and robust optomechanical system with a multitude of
long-lived () mechanical modes in a phononic-bandgap shielded membrane
resonator. An optical mode of a compact Fabry-Perot resonator detects these
modes' motion with a measurement rate () that exceeds the
mechanical decoherence rates already at moderate cryogenic temperatures
(). Reaching this quantum regime entails, i.~a., quantum
measurement backaction exceeding thermal forces, and thus detectable
optomechanical quantum correlations. In particular, we observe ponderomotive
squeezing of the output light mediated by a multitude of mechanical resonator
modes, with quantum noise suppression up to -2.4 dB (-3.6 dB if corrected for
detection losses) and bandwidths . The multi-mode
nature of the employed membrane and Fabry-Perot resonators lends itself to
hybrid entanglement schemes involving multiple electromagnetic, mechanical, and
spin degrees of freedom.Comment: 19 pages, 9 figure
Light-matter interactions in multi-element resonators
We investigate structural resonances in multi-element optical resonators and
provide a roadmap for the description of the interaction of single extended
cavity modes with quantum emitters or mechanical resonators. Using a first
principle approach based on the transfer matrix formalism we analyze, both
numerically and analytically, the static and dynamical properties of three- and
four-mirror cavities. We investigate in particular conditions under which the
confinement of the field in specific subcavities allows for enhanced
light-matter interactions in the context of cavity quantum electrodynamics and
cavity optomechanics
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