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Large deviations of heat flow in harmonic chains
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We consider heat transport across a harmonic chain connected at its two ends to white-noise Langevin reservoirs at different temperatures. In the steady state of this system the heat Q flowing from one reservoir into the system in a finite time τ has a distribution P(Q, τ). We study the large time form of the corresponding moment generating function lange - λQrang ~ g(λ)eτμ(λ). Exact formal expressions, in terms of phonon Green's functions, are obtained for both μ(λ) and also the lowest order correction g(λ). We point out that, in general, a knowledge of both μ(λ) and g(λ) is required for finding the large deviation function associated with P(Q, τ). The function μ(λ) is known to be the largest eigenvector of an appropriate Fokker-Planck type operator and our method also gives the corresponding eigenvector exactly
Born Rule(s)
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)This paper is based on work published in [1]. It describes a triple slit experiment using single photons that has been used to provide a bound on one of the most fundamental axioms of quantum mechanics i.e. Born's rule for probabilities [2]. In spite of being one of the most successful theories which describes various natural phenomena, quantum mechanics has enough intricacies and ``weirdness'' associated with it which makes many physicists believe that it may not be the final theory and hints towards the possibility of more generalized versions. Quantum interference as shown by a double slit diffraction experiment only occurs from pairs of paths. Even in multi-slit versions, interference can only occur between pairs of possibilities and increasing the number of slits does not increase the complexity of the theory that still remains second-order. However, more generalized versions of quantum mechanics may allow for multi-path i.e. higher than second order interference. This experiment also provides a bound on the magnitude of such higher order interference. We have been able to bound the magnitude of three-path interference to less than 10-2 of the expected two-path interference, thus ruling out third and higher order interference and providing a bound on the accuracy of Born's rule
Current status of the X-ray polarimeter
No full textOpen AccessWe describe the current status of a Thomson X-ray polarimeter developed for a small satellite mission. Currently, a laboratory model has been made and tested successfully and the design and fabrication of an engineering model is in progress. This involves, re-design of the currently developed lab model,
taking into consideration the different standards required for space qualification. We describe the design aspects of the detector, front-end electronics and the processing electronics
Interference detection in Gaussian noise
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)Interference detection in Gaussian noise is proposed. It can be applied for easy detection and editing of interference
lines in radio spectral line observations. One does not need to know the position of occurrence or keep track of
interference in the band. By using statistical properties of N-channel Gaussian noise it is possible to differentiate
interference from normal Gaussian noise. These statistical properties are three quantities which are calculated on
the subject spectrum. The first is the expected absolute maximum from the mean level across the spectrum. The
second is the expected absolute difference maximum (array of adjacent differences of channel values taken across
the spectrum), and the third is the expected absolute added difference maximum. For N-channel Gaussian noise,
these quantities have a well-defined value. Any deviation across the spectrum that violates an upper limit formed
by these expected maxima is attributed to interference. Results obtained on real data by applying this technique
have been displayed
Bidirectional transport in a multispecies totally asymmetric exclusion-process model
No full textOpen AccessWe study a minimal lattice model which describes bidirectional transport of “particles” driven along a onedimensional
track, as is observed in microtubule based, motor protein driven bidirectional transport of cargo
vesicles, lipid bodies, and organelles such asmitochondria. Thisminimal model, a multispecies totally asymmetric
exclusion process (TASEP) with directional switching, can provide a framework for understanding the interplay
between the switching dynamics of individual particles and the collectivemovement of particles in one dimension.
When switching is much faster than translocation, the steady-state density and current profiles of the particles
are homogeneous in the bulk and are well described by mean-field (MF) theory, as determined by comparison
to a Monte Carlo simulation. In this limit, we can map this model to the exactly solvable partially asymmetric
exclusion-process (PASEP) model. Away from this fast switching regime the MF theory fails, although the
average bulk density profile still remains homogeneous. We study the steady-state behavior as a function of the
ratio of the translocation and net switching rates Q and find a unique first-order phase transition at a finite Q
associated with a discontinuous change of the bulk density.When the switching rate is decreased further (keeping
translocation rate fixed), the system approaches a jammed phase with a net current that tends to zero as J ∼ 1/Q.
We numerically construct the phase diagram for finite Q
Robustness of non-gaussian entanglement against noisy amplifier and attenuator environments
No full textOpen accessThe recently developed Kraus representation for bosonic Gaussian channels is employed to study analytically the robustness of non-Gaussian entanglement against evolution under noisy attenuator and amplifier environments, and compare it with the robustness of Gaussian entanglement. Our results show that some non-Gaussian states with one ebit of entanglement are more robust than all Gaussian states, even the ones with arbitrarily large entanglement, a conclusion of direct consequence to the recent conjecture by Allegra et al. [Phys. Rev. Lett. 105, 100503 (2010)PRLTAO0031-900710.1103/PhysRevLett.105.100503]
Cross pairing of select and data voltages to display grayscales in liquid crystal displays
No full textRestricted Access.Successive approximation technique (SAT) has select
voltages of row waveforms paired up with data voltages of column
waveforms to achieve the maximum selection ratio. Cross pairing
of select and data voltages without compromising the selection
ratio generates more rms voltages as compared to SAT. Grayscales
can be displayed with less number of voltages in the addressing
waveforms and less number of time intervals in a cycle as compared
to SAT by cross pairing of select voltages with data voltages.
Better brightness uniformity among pixels that are driven to same
grayscale can be achieved by cross pairing because the width of
the select pulses increases due to less number of time intervals
in a cycle as compared to SAT. About 50% reduction in number
voltages in row waveforms and column waveforms in addition to
a 50% reduction in number of time intervals in a cycle can be
achieved as compared to SAT by cross pairing select and data voltage
Work fluctions for a harmonic oscillator driven by an external random force
No full textRestricted Access.The fluctuations of the work done by an external Gaussian random force on a harmonic
oscillator that is also in contact with a thermal bath are studied. We have obtained the exact large
deviation function as well as the complete asymptotic forms of the probability density function.
The distribution of the work done is found to be non-Gaussian. The steady-state fluctuation
theorem holds only if the ratio of the variances, of the external random forcing and the thermal
noise, respectively, is less than 1/3. On the other hand, the transient fluctuation theorem holds
(asymptotically) for all the values of that ratio. The theoretical asymptotic forms of the probability
density function are in very good agreement with the numerics as well as with an experiment
