4,705 research outputs found
Control over few photon pulses by a time-periodic modulation of the photon-emitter coupling
We develop a Floquet scattering formalism for the description of
quasistationary states of microwave photons in a one-dimensional waveguide
interacting with a nonlinear cavity by means of a periodically modulated
coupling. This model is inspired by the recent progress in engineering of
tunable coupling schemes with superconducting qubits. We argue that our model
can realize the quantum analogue of an optical chopper. We find strong periodic
modulations of the transmission and reflection envelopes in the scattered
few-photon pulses, including photon compression and blockade, as well as
dramatic changes in statistics. Our theoretical analysis allows us to explain
these non-trivial phenomena as arising from non-adiabatic memory effects.Comment: 12 pages, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1603.0549
Crossover critical behavior in the three-dimensional Ising model
The character of critical behavior in physical systems depends on the range
of interactions. In the limit of infinite range of the interactions, systems
will exhibit mean-field critical behavior, i.e., critical behavior not affected
by fluctuations of the order parameter. If the interaction range is finite, the
critical behavior asymptotically close to the critical point is determined by
fluctuations and the actual critical behavior depends on the particular
universality class. A variety of systems, including fluids and anisotropic
ferromagnets, belongs to the three-dimensional Ising universality class. Recent
numerical studies of Ising models with different interaction ranges have
revealed a spectacular crossover between the asymptotic fluctuation-induced
critical behavior and mean-field-type critical behavior. In this work, we
compare these numerical results with a crossover Landau model based on
renormalization-group matching. For this purpose we consider an application of
the crossover Landau model to the three-dimensional Ising model without fitting
to any adjustable parameters. The crossover behavior of the critical
susceptibility and of the order parameter is analyzed over a broad range (ten
orders) of the scaled distance to the critical temperature. The dependence of
the coupling constant on the interaction range, governing the crossover
critical behavior, is discussedComment: 10 pages in two-column format including 9 figures and 1 table.
Submitted to J. Stat. Phys. in honor of M. E. Fisher's 70th birthda
Non-adiabatic effects in periodically driven-dissipative open quantum systems
We present a general method to calculate the quasi-stationary state of a
driven-dissipative system coupled to a transmission line (and more generally,
to a reservoir) under periodic modulation of its parameters. Using Floquet's
theorem, we formulate the differential equation for the system's density
operator which has to be solved for a single period of modulation. On this
basis we also provide systematic expansions in both the adiabatic and
high-frequency regime. Applying our method to three different systems -- two-
and three-level models as well as the driven nonlinear cavity -- we propose
periodic modulation protocols of parameters leading to a temporary suppression
of effective dissipation rates, and study the arising non-adiabatic features in
the response of these systems.Comment: 12 pages, 8 figure
Efficient long distance quantum communication
Despite the tremendous progress of quantum cryptography, efficient quantum
communication over long distances (>1000km) remains an outstanding challenge
due to fiber attenuation and operation errors accumulated over the entire
communication distance. Quantum repeaters, as a promising approach, can
overcome both photon loss and operation errors, and hence significantly speedup
the communication rate. Depending on the methods used to correct loss and
operation errors, all the proposed QR schemes can be classified into three
categories (generations). Here we present the first systematic comparison of
three generations of quantum repeaters by evaluating the cost of both temporal
and physical resources, and identify the optimized quantum repeater
architecture for a given set of experimental parameters. Our work provides a
roadmap for the experimental realizations of highly efficient quantum networks
over transcontinental distances.Comment: Sreraman Muralidharan and Linshu Li contributed equally to this wor
Supply Chain Coordination with Quantity Discount for Seasonal Demand
Coordination between manufacturers and multiple buyers represents an important problem in supply chain management. In this paper, we develop a supply chain coordination mechanism in a system with a dominant manufacturer that delivers seasonal products to a group of buyers. These buyers have common replenishment times and receive delivery through a common delivery channel. A twice-stage ordering and production system is introduced in which the first order is placed at some time in advance of the selling season and a second order is placed closer to the selling period. This reorder strategy allows the buyer to collect additional information about seasonal demand, thereby reducing demand forecast error and simultaneously smoothing out production time. This twice-stage model results in savings for both manufacturer and the buyers. Strategies for developing sustainable cooperation between manufacturers and buyers are discussed in light of the conclusions of this model
Localization of phonon-polaritons in disordered polar media
The localization of the hybrid modes of phonons and photons in polar matter is investigated in the presence of random scatterers theoretically. We employ the self-consistent generalized Born-Huang approach to derive effective equations describing the phonon-polariton fields. Based on these equations, the density of states and
various localization properties are exploited in two-dimensional systems both analytically and numerically within the framework of the Anderson model with a non-Hermitian effective Hamiltonian. Consequently, it is
shown that the disorder effect brings some intriguing features which include the appearance of the localized states in the polariton bottleneck in the energy spectrum and the collapse of the energy gap. In addition, an analysis is given of the polariton level-spacing distribution.Russian Foundation for Basic Researc
Transverse coherence properties of X-ray beams in third-generation synchrotron radiation sources
This article describes a complete theory of spatial coherence for undulator
radiation sources. Current estimations of coherence properties often assume
that undulator sources are quasi-homogeneous, like thermal sources, and rely on
the application of the van Cittert-Zernike theorem for calculating the degree
of transverse coherence. Such assumption is not adequate when treating third
generation light sources, because the vertical(geometrical) emittance of the
electron beam is comparable or even much smaller than the radiation wavelength
in a very wide spectral interval that spans over four orders of magnitude (from
0.1 Angstrom up to 10^3 Angstrom). Sometimes, the so-called Gaussian-Schell
model, that is widely used in statistical optics in the description of
partially-coherent sources, is applied as an alternative to the
quasi-homogeneous model. However, as we will demonstrate, this model fails to
properly describe coherent properties of X-ray beams from non-homogeneous
undulator sources. As a result, a more rigorous analysis is required. We
propose a technique, based on statistical optics and Fourier optics, to
explicitly calculate the cross-spectral density of an undulator source in the
most general case, at any position after the undulator. Our theory, that makes
consistent use of dimensionless analysis, allows relatively easy treatment and
physical understanding of many asymptotes of the parameter space, together with
their region of applicability. Particular emphasis is given to the asymptotic
situation when the horizontal emittance is much larger than the radiation
wavelength, and the vertical emittance is arbitrary. This case is practically
relevant for third generation synchrotron radiation sources.Comment: 71 pages, 20 figures - Version accepted for publication in Nuclear
Inst. and Methods in Physics Research,
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