3,158 research outputs found
The prospect of detecting single-photon force effects in cavity optomechanics
Cavity optomechanical systems are approaching a strong-coupling regime where
the coherent dynamics of nanomechanical resonators can be manipulated and
controlled by optical fields at the single photon level. Here we propose an
interferometric scheme able to detect optomechanical coherent interaction at
the single-photon level which is experimentally feasible with state-of-the-art
devices.Comment: 8 pages, 2 figure
Entangling two distant non-interacting microwave modes
We propose a protocol able to prepare two remote and initially uncorrelated
microwave modes in an entangled stationary state, which is certifiable using
only local optical homodyne measurements. The protocol is an extension of
continuous variable entanglement swapping, and exploits two hybrid
quadripartite opto-electro-mechanical systems in which a nanomechanical
resonator acts as a quantum interface able to entangle optical and microwave
fields. The proposed protocol allows to circumvent the problems associated with
the fragility of microwave photons with respect to thermal noise and may
represent a fundamental tool for the realization of quantum networks connecting
distant solid-state and superconducting qubits, which are typically manipulated
with microwave fields. The certifying measurements on the optical modes
guarantee the success of entanglement swapping without the need of performing
explicit measurements on the distant microwave fields.Comment: 7 pages, 3 figures; to appear in the special issue "Quantum and
Hybrid Mechanical Systems - From Fundamentals to Applications" in Annalen der
Physi
Cavity Mode Frequencies and Strong Optomechanical Coupling in Two-Membrane Cavity Optomechanics
We study the cavity mode frequencies of a Fabry-P\'erot cavity containing two
vibrating dielectric membranes. We derive the equations for the mode resonances
and provide approximate analytical solutions for them as a function of the
membrane positions, which act as an excellent approximation when the relative
and center-of-mass position of the two membranes are much smaller than the
cavity length. With these analytical solutions, one finds that extremely large
optomechanical coupling of the membrane relative motion can be achieved in the
limit of highly reflective membranes when the two membranes are placed very
close to a resonance of the inner cavity formed by them. We also study the
cavity finesse of the system and verify that, under the conditions of large
coupling, it is not appreciably affected by the presence of the two membranes.
The achievable large values of the ratio between the optomechanical coupling
and the cavity decay rate, , make this two-membrane system the
simplest promising platform for implementing cavity optomechanics in the strong
coupling regime.Comment: Contribution to the special issue on "Nano-optomechanics" in Journal
of Optics, edited by I. Wilson-Rae, J. Sankey and H. Offerhau
Constructing finite dimensional codes with optical continuous variables
We show how a qubit can be fault-tolerantly encoded in the
infinite-dimensional Hilbert space of an optical mode. The scheme is efficient
and realizable with present technologies. In fact, it involves two travelling
optical modes coupled by a cross-Kerr interaction, initially prepared in
coherent states, one of which is much more intense than the other. At the exit
of the Kerr medium, the weak mode is subject to a homodyne measurement and a
quantum codeword is conditionally generated in the quantum fluctuations of the
intense mode.Comment: 7 pages, 5 figure
Observation of decoherence with a movable mirror
Recently it has been proposed to use parity as a measure of the mechanism
behind decoherence or the transformation from quantum to classical. Here, we
show that the proposed experiment is more feasible than previously thought, as
even an initial thermal state would exhibit the hypothesized symmetry breaking.Comment: Proceedings of the Lake Garda "quantum puzzles" conferenc
A model independent approach to non dissipative decoherence
We consider the case when decoherence is due to the fluctuations of some
classical variable or parameter of a system and not to its entanglement with
the environment. Under few and quite general assumptions, we derive a
model-independent formalism for this non-dissipative decoherence, and we apply
it to explain the decoherence observed in some recent experiments in cavity QED
and on trapped ions.Comment: 12 pages, 3 figure
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