525 research outputs found
Direct access to quantum fluctuations through cross-correlation measurements
Detection of the quantum fluctuations by conventional methods meets certain
obstacles, since it requires high frequency measurements. Moreover, quantum
fluctuations are normally dominated by classical noise, and are usually further
obstructed by various accompanying effects such as a detector backaction. In
present work, we demonstrate that these difficulties can be bypassed by
performing the cross-correlation measurements. We propose to use a pair of
two-level detectors, weakly coupled to a collective mode of an electric
circuit. Fluctuations of the current source accumulated in the collective mode
induce stochastic transitions in the detectors. These transitions are then read
off by quantum point contact (QPC) electrometers and translated into two
telegraph processes in the QPC currents. Since both detectors interact with the
same collective mode, this leads to a certain fraction of the correlated
transitions. These correlated transitions are fingerprinted in the
cross-correlations of the telegraph processes, which can be detected at zero
frequency, i.e., with a long time measurements. Concerning the dependance of
the cross-correlator on the detectors' energy splittings, the most interesting
region is at the degeneracy points, where it exhibits a sharp non-local
resonance, that stems from higher order processes. We find that at certain
conditions the main contribution to this resonance comes from the quantum
noise. Namely, while the resonance line shape is weakly broadened by the
classical noise, the height of the peak is directly proportional to the square
of the quantum component of the noise spectral function.Comment: Added discussion of the time scales in the introduction and one
figure. 14 pages, 8 figure
Multiparticle Interference, GHZ Entanglement, and Full Counting Statistics
We investigate the quantum transport in a generalized N-particle Hanbury
Brown--Twiss setup enclosing magnetic flux, and demonstrate that the Nth-order
cumulant of current cross correlations exhibits Aharonov-Bohm oscillations,
while there is no such oscillation in all the lower-order cumulants. The
multiparticle interference results from the orbital Greenberger-Horne-Zeilinger
entanglement of N indistinguishable particles. For sufficiently strong
Aharonov-Bohm oscillations the generalized Bell inequalities may be violated,
proving the N-particle quantum nonlocality.Comment: 4 pages, 1 figure, published versio
Transport Statistics of Bistable Systems
We consider the transport statistics of classical bistable systems driven by
noise. The stochastic path integral formalism is used to investigate the
dynamics and distribution of transmitted charge. Switching rates between the
two stable states are found from an instanton calculation, leading to an
effective two-state system on a long time scale. In the bistable current range,
the telegraph noise dominates the distribution, whose logarithm is found to be
universally described by a tilted ellipse.Comment: 4 pages, 3 figures, version to appear in Phys. Rev. Let
Plasmonic Bloch oscillations in chirped metal-dielectric structures
We study the propagation of plasmon polaritons in one-dimensional chirped metal-dielectric layered structures. We find an optical Wannier–Stark ladder in the mode spectrum and analyze Bloch oscillations associated with the coupling of surface plasmons localized at the metal-dielectric interfaces. For long structures, we find that the energy flow may dramatically change its direction, thus providing possibilities for the beam steering in the transmission band.The work has been supported by the Australian Research
Council
Semi-classical Theory of Conductance and Noise in Open Chaotic Cavities
Conductance and shot noise of an open cavity with diffusive boundary
scattering are calculated within the Boltzmann-Langevin approach. In
particular, conductance contains a non-universal geometric contribution,
originating from the presence of open contacts. Subsequently, universal
expressions for multi-terminal conductance and noise valid for all chaotic
cavities are obtained classically basing on the fact that the distribution
function in the cavity depends only on energy and using the principle of
minimal correlations.Comment: 4 pages, 1 .eps figur
Optical Bloch oscillations in periodic structures with metamaterials
We predict that optical Bloch oscillations can be observed in layered
structures with left-handed metamaterials and zero average refractive index
where the layer thickness varies linearly across the structure. We demonstrate
a new type of the Bloch oscillations associated with coupled surface waves
excited at the interfaces between the layers with left-handed material and
conventional dielectric.Comment: 3 pages, 5 postscript figure
Nonlinear optics and light localization in periodic photonic lattices
We review the recent developments in the field of photonic lattices
emphasizing their unique properties for controlling linear and nonlinear
propagation of light. We draw some important links between optical lattices and
photonic crystals pointing towards practical applications in optical
communications and computing, beam shaping, and bio-sensing.Comment: to appear in Journal of Nonlinear Optical Physics & Materials (JNOPM
Two-particle Aharonov-Bohm effect and Entanglement in the electronic Hanbury Brown Twiss setup
We analyze a Hanbury Brown Twiss geometry in which particles are injected
from two independent sources into a mesoscopic electrical conductor. The set-up
has the property that all partial waves end in different reservoirs without
generating any single particle interference. There is no single particle
Aharonov-Bohm effect. However, exchange effects lead to two-particle
Aharonov-Bohm oscillations in current correlations. We demonstrate that the
two-particle Aharonov-Bohm effect is connected to orbital entanglement which
can be used for violation of a Bell Inequality.Comment: 4 pages, 2 figures, discussion of postselected electron-electron
entanglement adde
Band structure and broadband compensation of absorption by amplification in layered optical metamaterials
The frequency dependence of the gain required to compensate for absorption is determined for a layered structure consisting of alternating absorbing and amplifying layers. It is shown that the fulfillment of the same conditions is required for the existence of a band structure consisting of alternating bands allowed and forbidden for optical radiation propagation in the frequency-wave vector parametric region. Conditions are found under which the gain required for compensation is smaller than thresholds for absolute (parasitic lasing) and convective (waveguide amplification of radiation) instabilities
Breakdown of Universality in Quantum Chaotic Transport: the Two-Phase Dynamical Fluid Model
We investigate the transport properties of open quantum chaotic systems in
the semiclassical limit. We show how the transmission spectrum, the conductance
fluctuations, and their correlations are influenced by the underlying chaotic
classical dynamics, and result from the separation of the quantum phase space
into a stochastic and a deterministic phase. Consequently, sample-to-sample
conductance fluctuations lose their universality, while the persistence of a
finite stochastic phase protects the universality of conductance fluctuations
under variation of a quantum parameter.Comment: 4 pages, 3 figures in .eps format; final version to appear in
Physical Review Letter
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