80 research outputs found
Classical aspects of Hawking radiation verified in analogue gravity experiment
There is an analogy between the propagation of fields on a curved spacetime
and shallow water waves in an open channel flow. By placing a streamlined
obstacle into an open channel flow we create a region of high velocity over the
obstacle that can include wave horizons. Long (shallow water) waves propagating
upstream towards this region are blocked and converted into short (deep water)
waves. This is the analogue of the stimulated Hawking emission by a white hole
(the time inverse of a black hole). The measurements of amplitudes of the
converted waves demonstrate that they appear in pairs and are classically
correlated; the spectra of the conversion process is described by a
Boltzmann-distribution; and the Boltzmann-distribution is determined by the
determined by the change in flow across the white hole horizon.Comment: 17 pages, 10 figures; draft of a chapter submitted to the proceedings
of the IX'th SIGRAV graduate school: Analogue Gravity, Lake Como, Italy, May
201
Experimental feasibility of measuring the gravitational redshift of light using dispersion in optical fibers
This paper describes a new class of experiments that use dispersion in
optical fibers to convert the gravitational frequency shift of light into a
measurable phase shift or time delay. Two conceptual models are explored. In
the first model, long counter-propagating pulses are used in a vertical fiber
optic Sagnac interferometer. The second model uses optical solitons in
vertically separated fiber optic storage rings. We discuss the feasibility of
using such an instrument to make a high precision measurement of the
gravitational frequency shift of light.Comment: 11 pages, 12 figure
All-optical versus electro-optical quantum-limited feedback
All-optical feedback can be effected by putting the output of a source cavity
through a Faraday isolator and into a second cavity which is coupled to the
source cavity by a nonlinear crystal. If the driven cavity is heavily damped,
then it can be adiabatically eliminated and a master equation or quantum
Langevin equation derived for the first cavity alone. This is done for an input
bath in an arbitrary state, and for an arbitrary nonlinear coupling. If the
intercavity coupling involves only the intensity (or one quadrature) of the
driven cavity, then the effect on the source cavity is identical to that which
can be obtained from electro-optical feedback using direct (or homodyne)
detection. If the coupling involves both quadratures, this equivalence no
longer holds, and a coupling linear in the source amplitude can produce a
nonclassical state in the source cavity. The analogous electro-optic scheme
using heterodyne detection introduces extra noise which prevents the production
of nonclassical light. Unlike the electro-optic case, the all-optical feedback
loop has an output beam (reflected from the second cavity). We show that this
may be squeezed, even if the source cavity remains in a classical state.Comment: 21 pages. This is an old (1994) paper, but one which I thought was
worth posting because in addition to what is described in abstract it has:
(1) the first formulation (to my knowledge) of quantum trajectories for an
arbitrary (i.e. squeezed, thermal etc.) broadband bath; (2) the prediction of
a periodic modification to the detuning and damping of an oscillator for the
simplest sort of all-optical feedback (i.e. a mirror) as seen in the recent
experiment "Forces between a Single Atom and Its Distant Mirror Image", P.
Bushev et al, Phys. Rev. Lett. 92, 223602 (2004
Mode structure and photon number correlations in squeezed quantum pulses
The question of efficient multimode description of optical pulses is studied.
We show that a relatively very small number of nonmonochromatic modes can be
sufficient for a complete quantum description of pulses with Gaussian
quadrature statistics. For example, a three-mode description was enough to
reproduce the experimental data of photon number correlations in optical
solitons [S. Spalter et al., Phys. Rev. Lett. 81, 786 (1998)]. This approach is
very useful for a detailed understanding of squeezing properties of soliton
pulses with the main potential for quantum communication with continuous
variables. We show how homodyne detection and/or measurements of photon number
correlations can be used to determine the quantum state of the multi-mode
field. We also discuss a possible way of physical separation of the
nonmonochromatic modes.Comment: 14 pages, 4 figures; minor revisions of the text, new references; to
appear in the Phys. Rev.
Robust transmission and reconstruction of fragile optical states
We propose a scheme by which signals carried by a coherent optical source close to the quantum noise limit can be amplified, making them more robust against losses, and then reconstructed at a remote site. The amplitude signal-to-noise ratio, the absolute amplitude noise level, and optical coherence are preserved. The scheme utilizes electro-optic feedforward and laser injection locking. We investigate the performance of the scheme as a quantum nondemolition device. [S1050-2947(97)02411-6]
Mode-Locking in Driven Disordered Systems as a Boundary-Value Problem
We study mode-locking in disordered media as a boundary-value problem.
Focusing on the simplest class of mode-locking models which consists of a
single driven overdamped degree-of-freedom, we develop an analytical method to
obtain the shape of the Arnol'd tongues in the regime of low ac-driving
amplitude or high ac-driving frequency. The method is exact for a scalloped
pinning potential and easily adapted to other pinning potentials. It is
complementary to the analysis based on the well-known Shapiro's argument that
holds in the perturbative regime of large driving amplitudes or low driving
frequency, where the effect of pinning is weak.Comment: 6 pages, 7 figures, RevTeX, Submitte
Soliton back-action evading measurement using spectral filtering
We report on a back-action evading (BAE) measurement of the photon number of
fiber optical solitons operating in the quantum regime. We employ a novel
detection scheme based on spectral filtering of colliding optical solitons. The
measurements of the BAE criteria demonstrate significant quantum state
preparation and transfer of the input signal to the signal and probe outputs
exiting the apparatus, displaying the quantum-nondemolition (QND) behavior of
the experiment.Comment: 5 pages, 5 figure
New Lump-like Structures in Scalar-field Models
In this work we investigate lump-like solutions in models described by a
single real scalar field. We start considering non-topological solutions with
the usual lump-like form, and then we study other models, where the bell-shape
profile may have varying amplitude and width, or develop a flat plateau at its
top, or even induce a lump on top of another lump. We suggest possible
applications where these exotic solutions might be used in several distinct
branches of physics.Comment: REvTex4, twocolumn, 10 pages, 9 figures; new reference added, to
appear in EPJ
All-optical switching and strong coupling using tunable whispering-gallery-mode microresonators
We review our recent work on tunable, ultrahigh quality factor
whispering-gallery-mode bottle microresonators and highlight their applications
in nonlinear optics and in quantum optics experiments. Our resonators combine
ultra-high quality factors of up to Q = 3.6 \times 10^8, a small mode volume,
and near-lossless fiber coupling, with a simple and customizable mode structure
enabling full tunability. We study, theoretically and experimentally, nonlinear
all-optical switching via the Kerr effect when the resonator is operated in an
add-drop configuration. This allows us to optically route a single-wavelength
cw optical signal between two fiber ports with high efficiency. Finally, we
report on progress towards strong coupling of single rubidium atoms to an
ultra-high Q mode of an actively stabilized bottle microresonator.Comment: 20 pages, 24 figures. Accepted for publication in Applied Physics B.
Changes according to referee suggestions: minor corrections to some figures
and captions, clarification of some points in the text, added references,
added new paragraph with results on atom-resonator interactio
Three-dimensional quantization of the electromagnetic field in dispersive and absorbing inhomogeneous dielectrics
A quantization scheme for the phenomenological Maxwell theory of the full
electromagnetic field in an inhomogeneous three-dimensional, dispersive and
absorbing dielectric medium is developed. The classical Maxwell equations with
spatially varying and Kramers-Kronig consistent permittivity are regarded as
operator-valued field equations, introducing additional current- and
charge-density operator fields in order to take into account the noise
associated with the dissipation in the medium. It is shown that the equal-time
commutation relations between the fundamental electromagnetic fields
and and the potentials and in the Coulomb gauge
can be expressed in terms of the Green tensor of the classical problem. From
the Green tensors for bulk material and an inhomogeneous medium consisting of
two bulk dielectrics with a common planar interface it is explicitly proven
that the well-known equal-time commutation relations of QED are preserved
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