434 research outputs found
A dynamical model for quantum memory channels
A dynamical model for quantum channel is introduced which allows one to pass
continuously from the memoryless case to the case in which memory effects are
present. The quantum and classical communication rates of the model are defined
and explicit expression are provided in some limiting case. In this context we
introduce noise attenuation strategies where part of the signals are sacrificed
to modify the channel environment. The case of qubit channel with phase damping
noise is analyzed in details.Comment: 11 pages, 4 figures; minor correction adde
Sensing using differential surface plasmon ellipsometry
Copyright © 2004 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics 96 (2004) and may be found at http://link.aip.org/link/?JAPIAU/96/3004/1In this work a differential ellipsometric method utilizing surface plasmons (SPs) for monitoring refractive index changes, which could be used in chemical and biological sensors, is presented. The method is based upon determining the azimuth of elliptically polarized light reflected from a Kretschmann SP system, resulting from linearly polarized light containing both p and s components incident upon it. The sensitivity of this azimuth to the refractive index of a dielectric on the nonprism side of the metal film is demonstrated both experimentally and theoretically. The smallest refractive index change which is resolvable is of the order of 10–7 refractive index units, although it is believed that this could be improved upon were it not for experimental constraints due to atmospheric changes and vibrations. The method requires the Kretschmann configuration to be oriented at a fixed angle, and the SP to be excited at a fixed wavelength. With no moving parts this method would be particularly robust from an application point of view
Forty-Four Pass Fibre Optic Loop for Improving the Sensitivity of Surface Plasmon Resonance Sensors
A forty-four pass fibre optic surface plasmon resonance sensor that enhances
detection sensitivity according to the number of passes is demonstrated for the
first time. The technique employs a fibre optic recirculation loop that passes
the detection spot forty- four times, thus enhancing sensitivity by a factor of
forty-four. Presently, the total number of passes is limited by the onset of
lasing action of the recirculation loop. This technique offers a significant
sensitivity improvement for various types of plasmon resonance sensors that may
be used in chemical and biomolecule detections.Comment: Submitted for publication; patent disclosure submitte
Vacuum Rabi splitting and strong coupling dynamics for surface plasmon polaritons and Rhodamine 6G molecules
We report on strong coupling between surface plasmon polaritons (SPP) and
Rhodamine 6G (R6G) molecules, with double vacuum Rabi splitting energies up to
230 and 110 meV. In addition, we demonstrate the emission of all three energy
branches of the strongly coupled SPP-exciton hybrid system, revealing features
of system dynamics that are not visible in conventional reflectometry. Finally,
in analogy to tunable-Q microcavities, we show that the Rabi splitting can be
controlled by adjusting the interaction time between waveguided SPPs and R6G
deposited on top of the waveguide. The interaction time can be controlled with
sub-fs precision by adjusting the length of the R6G area with standard
lithography methods.Comment: 4 pages, 4 figure
Long-range surface plasmon polariton excitation at the quantum level
We provide the quantum mechanical description of the excitation of long-range
surface plasmon polaritons (LRSPPs) on thin metallic strips. The excitation
process consists of an attenuated-reflection setup, where efficient
photon-to-LRSPP wavepacket-transfer is shown to be achievable. For calculating
the coupling, we derive the first quantization of LRSPPs in the polaritonic
regime. We study quantum statistics during propagation and characterize the
performance of photon-to-LRSPP quantum state transfer for single-photons,
photon-number states and photonic coherent superposition states.Comment: 9 pages, 6 figures, RevTeX4; Accepted versio
Simultaneous Surface Plasmon Resonance and X-ray Absorption Spectroscopy
We present here an experimental set-up to perform simultaneously measurements
of surface plasmon resonance (SPR) and X-ray absorption spectroscopy (XAS) in a
synchrotron beamline. The system allows measuring in situ and in real time the
effect of X-ray irradiation on the SPR curves to explore the interaction of
X-rays with matter. It is also possible to record XAS spectra while exciting
SPR in order to detect the changes in the electronic configuration of thin
films induced by the excitation of surface plasmons. Combined experiments
recording simultaneously SPR and XAS curves while scanning different parameters
can be carried out. The relative variations in the SPR and XAS spectra that can
be detected with this set-up ranges from 10-3 to 10-5, depending on the
particular experiment
Strongly coupled surface plasmons on thin shallow metallic gratings
Z. Chen, Ian R. Hooper, and J. Roy Sambles, Physical Review B, Vol. 77, article 161405(R) (2008). Copyright © 2008 by the American Physical Society.The optical response of a thin metallic film with shallow corrugations on both surfaces is explored and the structure is found to support a strongly coupled surface plasmon polariton when transverse magnetic radiation is incident in a plane parallel to the grating grooves. Modeling confirms that this strongly excited mode is the short range surface plasmon polariton and its presence is confirmed experimentally in the visible part of the spectrum
Simple test for quantum channel capacity
Basing on states and channels isomorphism we point out that semidefinite
programming can be used as a quick test for nonzero one-way quantum channel
capacity. This can be achieved by search of symmetric extensions of states
isomorphic to a given quantum channel. With this method we provide examples of
quantum channels that can lead to high entanglement transmission but still have
zero one-way capacity, in particular, regions of symmetric extendibility for
isotropic states in arbitrary dimensions are presented. Further we derive {\it
a new entanglement parameter} based on (normalised) relative entropy distance
to the set of states that have symmetric extensions and show explicitly the
symmetric extension of isotropic states being the nearest to singlets in the
set of symmetrically extendible states. The suitable regularisation of the
parameter provides a new upper bound on one-way distillable entanglement.Comment: 6 pages, no figures, RevTeX4. Signifficantly corrected version. Claim
on continuity of channel capacities removed due to flaw in the corresponding
proof. Changes and corrections performed in the part proposing a new upper
bound on one-way distillable etanglement which happens to be not one-way
entanglement monoton
Grating-coupled surface plasmons at microwave frequencies
Copyright © 1999 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics 86 (1999) and may be found at: http://link.aip.org/link/?JAPIAU/86/1791/1This work presents a detailed investigation of electromagnetic coupling to the surface plasmon-polariton (SPP) at microwave frequencies. We have recorded the wavelength-dependent reflectivity from a metallic sinusoidal diffraction grating of pitch 15 mm. In order to minimize the problems associated with nonplanar incident wavefronts, we have developed an apparatus that collimates the incident beam. We illustrate resonant coupling to the SPP at wavelengths of the order of 10 mm. The wavelength-dependent reflectivities recorded have been successfully fitted using a differential formalism of conical diffraction with a single set of grating parameters describing the grating profile and metal permittivity
The physical meaning of the "boost-rotation symmetric" solutions within the general interpretation of Einstein's theory of gravitation
The answer to the question, what physical meaning should be attributed to the
so-called boost-rotation symmetric exact solutions to the field equations of
general relativity, is provided within the general interpretation scheme for
the ``theories of relativity'', based on group theoretical arguments, and set
forth by Erich Kretschmann already in the year 1917.Comment: 9 pages, 1 figure; text to appear in General Relativity and
Gravitatio
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