109 research outputs found
Quantumness of correlations and Maxwell's demons in elementary scattering processes—Energetic consequences
The interactions between physical systems generally lead to the formation of correlations. In this paper we consider the phenomena of entanglement and "quantumness of correlations", such as quantum discord, with particular emphasis on their energetic consequences for the participating systems. We describe a number of theoretical models that are commonly employed in this context, highlighting the general character of one of their most intriguing results: In contradiction to conventional expectations, erasure (decay, consumption) of quantum correlations may be a source of work, i.e. may have "negative energetic costs". We report experimental evidence of this surprising effect obtained within the framework of an elementary scattering experiment, namely ultrafast neutron Compton scattering from normal-state liquid 4He. The general theory of quantumness of correlations provides a natural way of interpreting the reported results, which stand in blatant contrast to the conventional theory of scattering, where neutron-atom-environment quantum correlations and decoherence play no role. Moreover, they provide a new operational meaning of discord and related measures of quantumness
Partial Wave Analysis of Scattering with Nonlocal Aharonov-Bohm Effect and Anomalous Cross Section induced by Quantum Interference
Partial wave theory of a three dmensional scattering problem for an arbitray
short range potential and a nonlocal Aharonov-Bohm magnetic flux is
established. The scattering process of a ``hard shere'' like potential and the
magnetic flux is examined. An anomalous total cross section is revealed at the
specific quantized magnetic flux at low energy which helps explain the
composite fermion and boson model in the fractional quantum Hall effect. Since
the nonlocal quantum interference of magnetic flux on the charged particles is
universal, the nonlocal effect is expected to appear in quite general potential
system and will be useful in understanding some other phenomena in mesoscopic
phyiscs.Comment: 6 figure
A Statistical Description of Molecular Dynamical Processes in Liquids. Application to FIR Absorption Spectroscopy
The basic physical concepts concerning the derivation and
validity of the generalized fluctuation-dissipation theorem (FDT)
as revealed in an earlier paper11 are discussed. It is shown that
dissipation of irradiation within the framework of Kubo\u27s linear
response theory is mainly due (i) to the short-time behavior of the
coupling operator of a system with the irradiation field, (ii) to the
spontaneous fluctuations concerning the statistical operator in the
microscopic time scale, and (iii) to the explicit introduction of the
coupling of the systems with the thermal bath in Kubo\u27s formalism,
as proposed by van Vliet.
As a result, the statistical operator becomes time dependent
in the shorttime range. Within Kubo\u27s microscopic theory of irreversible
processes the generalized FDT also delivers a microscopic
interpretation of Prigogine\u27s theorem of minimum entropy production
(TMEP)
Spontaneous spin bifurcations and ferromagnetic phase transitions in a spinor exciton-polariton condensate
We observe a spontaneous parity breaking bifurcation to a ferromagnetic state
in a spatially trapped exciton-polariton condensate. At a critical bifurcation
density under nonresonant excitation, the whole condensate spontaneously
magnetizes and randomly adopts one of two elliptically polarized (up to 95%
circularly-polarized) states with opposite handedness of polarization. The
magnetized condensate remains stable for many seconds at 5 K, but at higher
temperatures it can flip from one magnetic orientation to another. We optically
address these states and demonstrate the inversion of the magnetic state by
resonantly injecting 100-fold weaker pulses of opposite spin. Theoretically,
these phenomena can be well described as spontaneous symmetry breaking of the
spin degree of freedom induced by different loss rates of the linear
polarizations.This work was supported by Grants EPSRC No. EP/G060649/1, EU No. CLERMONT4 235114, EU No. INDEX 289968, Spanish MEC (MAT2008-01555), Greek GSRT ARISTEIA Apollo program and Fundación La Caixa, and Mexican CONACYT No. 251808. FP acknowledges financial support through an EPSRC doctoral prize fellowship at the University of Cambridge and a Schrödinger fellowship at the University of Oxford.This is the final version of the article. It first appeared from the American Physical Society via http://dx.doi.org/10.1103/PhysRevX.5.03100
Single-molecule optomechanics in "picocavities"
Trapping light with noble metal nanostructures overcomes the diffraction limit and can confine light to volumes typically on the order of 30 cubic nanometers. We found that individual atomic features inside the gap of a plasmonic nanoassembly can localize light to volumes well below 1 cubic nanometer ("picocavities"), enabling optical experiments on the atomic scale. These atomic features are dynamically formed and disassembled by laser irradiation. Although unstable at room temperature, picocavities can be stabilized at cryogenic temperatures, allowing single atomic cavities to be probed for many minutes. Unlike traditional optomechanical resonators, such extreme optical confinement yields a factor of 10 enhancement of optomechanical coupling between the picocavity field and vibrations of individual molecular bonds. This work sets the basis for developing nanoscale nonlinear quantum optics on the single-molecule level.Supported by Project FIS2013-41184-P from MINECO (Ministerio de EconomĂa y Competitividad) and IT756-13 from the Basque government consolidated groups (M.K.S., Y.Z., A. Demetriadou, R.E., and J.A.); the Winton Programme for the Physics of Sustainability (F.B.); the Dr. Manmohan Singh scholarship from St. John’s College (R.C.); the UK National Physical Laboratory (C.C.); the Fellows Gipuzkoa Program of the Gipuzkoako Foru Aldundia via FEDER funds of the European Union “Una manera de hacer Europa” (R.E.); UK Engineering and Physical Sciences Research Council grants EP/G060649/1 and EP/L027151/1; and European Research Council grant LINASS 320503
Correlation property of length sequences based on global structure of complete genome
This paper considers three kinds of length sequences of the complete genome.
Detrended fluctuation analysis, spectral analysis, and the mean distance
spanned within time are used to discuss the correlation property of these
sequences. The values of the exponents from these methods of these three kinds
of length sequences of bacteria indicate that the long-range correlations exist
in most of these sequences. The correlation have a rich variety of behaviours
including the presence of anti-correlations. Further more, using the exponent
, it is found that these correlations are all linear (). It is also found that these sequences exhibit noise in some
interval of frequency (). The length of this interval of frequency depends
on the length of the sequence. The shape of the periodogram in exhibits
some periodicity. The period seems to depend on the length and the complexity
of the length sequence.Comment: RevTex, 9 pages with 5 figures and 3 tables. Phys. Rev. E Jan. 1,2001
(to appear
Measure representation and multifractal analysis of complete genomes
This paper introduces the notion of measure representation of DNA sequences.
Spectral analysis and multifractal analysis are then performed on the measure
representations of a large number of complete genomes. The main aim of this
paper is to discuss the multifractal property of the measure representation and
the classification of bacteria. From the measure representations and the values
of the spectra and related curves, it is concluded that these
complete genomes are not random sequences. In fact, spectral analyses performed
indicate that these measure representations considered as time series, exhibit
strong long-range correlation. For substrings with length K=8, the
spectra of all organisms studied are multifractal-like and sufficiently smooth
for the curves to be meaningful. The curves of all bacteria
resemble a classical phase transition at a critical point. But the 'analogous'
phase transitions of chromosomes of non-bacteria organisms are different. Apart
from Chromosome 1 of {\it C. elegans}, they exhibit the shape of double-peaked
specific heat function.Comment: 12 pages with 9 figures and 1 tabl
Decoherence, einselection, and the quantum origins of the classical
Decoherence is caused by the interaction with the environment. Environment
monitors certain observables of the system, destroying interference between the
pointer states corresponding to their eigenvalues. This leads to
environment-induced superselection or einselection, a quantum process
associated with selective loss of information. Einselected pointer states are
stable. They can retain correlations with the rest of the Universe in spite of
the environment. Einselection enforces classicality by imposing an effective
ban on the vast majority of the Hilbert space, eliminating especially the
flagrantly non-local "Schr\"odinger cat" states. Classical structure of phase
space emerges from the quantum Hilbert space in the appropriate macroscopic
limit: Combination of einselection with dynamics leads to the idealizations of
a point and of a classical trajectory. In measurements, einselection replaces
quantum entanglement between the apparatus and the measured system with the
classical correlation.Comment: Final version of the review, with brutally compressed figures. Apart
from the changes introduced in the editorial process the text is identical
with that in the Rev. Mod. Phys. July issue. Also available from
http://www.vjquantuminfo.or
Spontaneous spin bifurcations and ferromagnetic phase transitions in a spinor exciton-polariton condensate
We observe a spontaneous parity breaking bifurcation to a ferromagnetic state in a spatially trapped exciton-polariton condensate. At a critical bifurcation density under nonresonant excitation, the whole condensate spontaneously magnetizes and randomly adopts one of two elliptically polarized (up to 95% circularly polarized) states with opposite handedness of polarization. The magnetized condensate remains stable for many seconds at 5 K, but at higher temperatures, it can flip from one magnetic orientation to another. We optically address these states and demonstrate the inversion of the magnetic state by resonantly injecting 100- fold weaker pulses of opposite spin. Theoretically, these phenomena can be well described as spontaneous symmetry breaking of the spin degree of freedom induced by different loss rates of the linear polarizations.Publisher PDFPeer reviewe
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