220 research outputs found
Direct sampling of the Susskind-Glogower phase distributions
Coarse-grained phase distributions are introduced that approximate to the
Susskind--Glogower cosine and sine phase distributions. The integral relations
between the phase distributions and the phase-parametrized field-strength
distributions observable in balanced homodyning are derived and the integral
kernels are analyzed. It is shown that the phase distributions can be directly
sampled from the field-strength distributions which offers the possibility of
measuring the Susskind--Glogower cosine and sine phase distributions with
sufficiently well accuracy. Numerical simulations are performed to demonstrate
the applicability of the method.Comment: 10 figures using a4.st
Sampling the canonical phase from phase-space functions
We discuss the possibility of sampling exponential moments of the canonical
phase from the s-parametrized phase space functions. We show that the sampling
kernels exist and are well-behaved for any s>-1, whereas for s=-1 the kernels
diverge in the origin. In spite of that we show that the phase space moments
can be sampled with any predefined accuracy from the Q-function measured in the
double-homodyne scheme with perfect detectors. We discuss the effect of
imperfect detection and address sampling schemes using other measurable
phase-space functions. Finally, we discuss the problem of sampling the
canonical phase distribution itself.Comment: 10 pages, 7 figures, REVTe
Direct sampling of exponential phase moments of smoothed Wigner functions
We investigate exponential phase moments of the s-parametrized
quasidistributions (smoothed Wigner functions). We show that the knowledge of
these moments as functions of s provides, together with photon-number
statistics, a complete description of the quantum state. We demonstrate that
the exponential phase moments can be directly sampled from the data recorded in
balanced homodyne detection and we present simple expressions for the sampling
kernels. The phase moments are Fourier coefficients of phase distributions
obtained from the quasidistributions via integration over the radial variable
in polar coordinates. We performed Monte Carlo simulations of the homodyne
detection and we demonstrate the feasibility of direct sampling of the moments
and subsequent reconstruction of the phase distribution.Comment: RevTeX, 8 pages, 6 figures, accepted Phys. Rev.
Measuring the elements of the optical density matrix
Most methods for experimentally reconstructing the quantum state of light
involve determining a quasiprobability distribution such as the Wigner
function. In this paper we present a scheme for measuring individual density
matrix elements in the photon number state representation. Remarkably, the
scheme is simple, involving two beam splitters and a reference field in a
coherent state.Comment: 6 pages and 1 figur
Josephson Plasma in RuSr2GdCu2O8
Josephson plasma in RuSrGdCuO,
RuSrGdCuO (x = 0.3), and
RuSrEuCeCuO (x = 0.5) compounds is
investigated by the sphere resonance method. The Josephson plasma is observed
in a low-frequency region (around 8.5 cm at T ) for
ferromagnetic RuSrGdCuO, while it increases to 35 cm
for non-ferromagnetic RuSrGdCuO (x = 0.3), which
represents a large reduction in the Josephson coupling at ferromagnetic
RuO block layers. The temperature dependence of the plasma does not shift
to zero frequency ({\it i.e.} = 0) at low temperatures, indicating that
there is no transition from the 0-phase to the -phase in these compounds.
The temperature dependence and the oscillator strength of the peak are
different from those of other non-magnetic cuprates, and the origins of these
anomalies are discussed.Comment: to appear in Phys. Rev.B Rapid Com
Pseudogap formation of four-layer BaRuO and its electrodynamic response changes
We investiaged the optical properties of four-layer BaRuO, which shows
a fermi-liquid-like behavior at low temperature. Its optical conductivity
spectra clearly displayed the formation of a pseudogap and the development of a
coherent peak with decreasing temperature. Temperature-dependences of the
density and the scattering rate of the coherent component were
also derived. As the temperature decreases, both and decrease for
four-layer BaRuO. These electrodynamic responses were compared with those
of nine-layer BaRuO, which also shows a pseudogap formation but has an
insulator-like state at low temperature. It was found that the relative rates
of change of both and determine either metallic or insulator-like
responses in the ruthenates. The optical properties of the four-layer ruthenate
were also compared with those of other pseudogap systems, such as high
cuprates and heavy electron systems.Comment: 7 figures. submitted to Phys. Rev.
Machine learning for estimation of building energy consumption and performance:a review
Ever growing population and progressive municipal business demands for constructing new buildings are known as the foremost contributor to greenhouse gasses. Therefore, improvement of energy eciency of the building sector has become an essential target to reduce the amount of gas emission as well as fossil fuel consumption. One most eective approach to reducing CO2 emission and energy consumption with regards to new buildings is to consider energy eciency at a very early design stage. On the other hand, ecient energy management and smart refurbishments can enhance energy performance of the existing stock. All these solutions entail accurate energy prediction for optimal decision making. In recent years, articial intelligence (AI) in general and machine learning (ML) techniques in specic terms have been proposed for forecasting of building energy consumption and performance. This paperprovides a substantial review on the four main ML approaches including articial neural network, support vector machine, Gaussian-based regressions and clustering, which have commonly been applied in forecasting and improving building energy performance
Effect of event selection on jetlike correlation measurement in d+Au collisions at sNN=200 GeV
AbstractDihadron correlations are analyzed in sNN=200 GeV d+Au collisions classified by forward charged particle multiplicity and zero-degree neutral energy in the Au-beam direction. It is found that the jetlike correlated yield increases with the event multiplicity. After taking into account this dependence, the non-jet contribution on the away side is minimal, leaving little room for a back-to-back ridge in these collisions
J/ψ polarization in p+p collisions at s=200 GeV in STAR
AbstractWe report on a polarization measurement of inclusive J/ψ mesons in the di-electron decay channel at mid-rapidity at 2<pT<6 GeV/c in p+p collisions at s=200 GeV. Data were taken with the STAR detector at RHIC. The J/ψ polarization measurement should help to distinguish between different models of the J/ψ production mechanism since they predict different pT dependences of the J/ψ polarization. In this analysis, J/ψ polarization is studied in the helicity frame. The polarization parameter λθ measured at RHIC becomes smaller towards high pT, indicating more longitudinal J/ψ polarization as pT increases. The result is compared with predictions of presently available models
Beam-energy Dependence Of Charge Balance Functions From Au + Au Collisions At Energies Available At The Bnl Relativistic Heavy Ion Collider
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Balance functions have been measured in terms of relative pseudorapidity (Δη) for charged particle pairs at the BNL Relativistic Heavy Ion Collider from Au + Au collisions at sNN=7.7GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at sNN=2.76TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). The narrowing of the balance function in central collisions at sNN=7.7 GeV implies that a QGP is still being created at this relatively low energy. © 2016 American Physical Society.942CNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoMinistry of Education and Science of the Russian FederationMOE, Ministry of Education of the People's Republic of ChinaMOST, Ministry of Science and Technology of the People's Republic of ChinaNRF-2012004024, National Research FoundationNSF, National Stroke FoundationConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
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