41,243 research outputs found
Engineering the accurate distortion of an object's temperature-distribution signature
It is up to now a challenge to control the conduction of heat. Here we
develop a method to distort the temperature distribution signature of an object
at will. As a result, the object accurately exhibits the same temperature
distribution signature as another object that is predetermined, but actually
does not exist in the system. Our finite element simulations confirm the
desired effect for different objects with various geometries and compositions.
The underlying mechanism lies in the effects of thermal metamaterials designed
by using this method. Our work is of value for applications in thermal
engineering.Comment: 11 pages, 4 figure
Dynamics of quantum-classical hybrid system: effect of matter-wave pressure
Radiation pressure affects the kinetics of a system exposed to the radiation
and it constitutes the basis of laser cooling. In this paper, we study {\it
matter-wave pressure} through examining the dynamics of a quantum-classical
hybrid system. The quantum and classical subsystem have no explicit coupling to
each other, but affect mutually via a changing boundary condition. Two systems,
i.e., an atom and a Bose-Einstein condensate(BEC), are considered as the
quantum subsystems, while an oscillating wall is taken as the classical
subsystem. We show that the classical subsystem would experience a force
proportional to from the quantum atom, whereas it acquires an
additional force proportional to from the BEC due to the atom-atom
interaction in the BEC. These forces can be understood as the {\it matter-wave
pressure}.Comment: 7 pages, 6 figue
CRLBs for Pilot-Aided Channel Estimation in OFDM System under Gaussian and Non-Gaussian Mixed Noise
The determination of Cramer-Rao lower bound (CRLB) as an optimality criterion for the problem of channel estimation in wireless communication is a very important issue. Several CRLBs on channel estimation have been derived for Gaussian noise. However, a practical channel is affected by not only Gaussian background noise but also non-Gaussian noise such as impulsive interference. This paper derives the deterministic and stochastic CRLBs for Gaussian and non-Gaussian mixed noise. Due to the use of the non-parametric kernel method to build the PDF of non-Gaussian noise, the proposed CRLBs are suitable for practical channel environments with various noise distributions
Evidence of Electron Fractionalization from Photoemission Spectra in the High Temperature Superconductors
In the normal state of the high temperature superconductors
Bi_2Sr_2CaCu_2O_{8+delta} and La_{2-x}Sr_{x}CuO_4, and in the related ``stripe
ordered'' material La_1.25Nd_0.6Sr_0.15CuO_4, there is sharp structure in the
measured single hole spectral function A(k,w) considered as a function of k at
fixed small binding energy w. At the same time, as a function of w at fixed k
on much of the putative Fermi surface, any structure in A(k,w), other than the
Fermi cutoff, is very broad. This is characteristic of the situation in which
there are no stable excitations with the quantum numbers of the electron, as is
the case in the one dimensional electron gas.Comment: Published versio
Thermodynamics with density and temperature dependent particle masses and properties of bulk strange quark matter and strangelets
Thermodynamic formulas for investigating systems with density and/or
temperature dependent particle masses are generally derived from the
fundamental derivation equality of thermodynamics. Various problems in the
previous treatments are discussed and modified. Properties of strange quark
matter in bulk and strangelets at both zero and finite temperature are then
calculated based on the new thermodynamic formulas with a new quark mass
scaling, which indicates that low mass strangelets near beta equilibrium are
multi-quark states with an anti-strange quark, such as the pentaquark
(u^2d^2\bar{s}) for baryon nmber 1 and the octaquark (u^4d^3\bar{s}) for
dibaryon etc.Comment: 14 pages, 12 figures, Revtex4 styl
Low-Energy Electronic Structure of the High-Tc Cuprates La2-xSrxCuO4 Studied by Angle-resolved Photoemission Spectroscopy
We have performed a systematic angle-resolved photoemission spectroscopy
(ARPES) study of the high-Tc cuprates La2-xSrxCuO4, ranging from the underdoped
insulator to the superconductor to the overdoped metal. We have revealed a
systematic doping evolution of the band dispersions and (underlying) Fermi
surfaces, pseudogap and quasi-particle features under the influence of strong
electron-electron interaction and electron-phonon interaction. The unusual
transport and thermodynamic properties are explained by taking into account the
pseudogap opening and the Fermi arc formation, due to which the carrier number
decreases as the doped hole concentration decreases.Comment: 27 pages, 17 figures, accepted in Journal of Physics Condensed Matte
Underlying Fermi surface of SrCaCuO in two-dimensional momentum space observed by angle-resolved photoemission spectroscopy
We have performed an angle-resolved photoemission study of the two-leg ladder
system SrCaCuO with = 0 and 11. "Underlying Fermi
surfaces" determined from low energy spectral weight mapping indicates the
quasi-one dimensional nature of the electronic structure. Energy gap caused by
the charge density wave has been observed for =0 and the gap tends to close
with Ca substitution. The absence of a quasi-particle peak even in =11 is in
contrast to the two-dimensional high- cuprates, implying strong carrier
localization related to the hole crystalization.Comment: 5 pages, 3 figure
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