共查询到20条相似文献,搜索用时 15 毫秒
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Vladimir I. Shashkin Yuri A. Drjagin Vjacheslav R. Zakamov Sergei V. Krivov Lev M. Kukin Arcady V. Murel Yuri I. Chechenin 《International Journal of Infrared and Millimeter Waves》2007,28(11):945-952
The principles of construction of millimeter wave detectors based on low-barrier Schottky diodes and planar antennas are discussed.
The modified planar slot antenna with low beam spillover at the resonant frequency of 94 GHz has been developed. Experiments
have been carried out to investigate detecting characteristics of the diodes with differential contact resistances at zero bias. Experimental data are well correspond to calculations in a simple model of detector. At the maximum of rf-to-dc voltage sensitivity - more than 10000 V/W - is obtained. At lower values of a better noise equivalent power (NEP), around 10−12 W Hz−1/2, is predicted. 相似文献
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We present the main ingredients of twistor theory leading up to and including the Penrose-Ward transform in a coordinate algebra
form which we can then ‘quantise’ by means of a functorial cocycle twist. The quantum algebras for the conformal group, twistor
space , compactified Minkowski space and the twistor correspondence space are obtained along with their canonical quantum differential calculi, both in a local
form and in a global *-algebra formulation which even in the classical commutative case provides a useful alternative to the
formulation in terms of projective varieties. We outline how the Penrose-Ward transform then quantises. As an example, we
show that the pull-back of the tautological bundle on pulls back to the basic instanton on and that this observation quantises to obtain the Connes-Landi instanton on θ-deformed S
4 as the pull-back of the tautological bundle on our θ-deformed . We likewise quantise the fibration and use it to construct the bundle on θ-deformed that maps over under the transform to the θ-deformed instanton.
The work was mainly completed while S.M. was visiting July-December 2006 at the Isaac Newton Institute, Cambridge, which both
authors thank for support. 相似文献
5.
Kunji Nakayama 《International Journal of Theoretical Physics》2008,47(7):2065-2094
This paper deals with topos-theoretic truth-value valuations of quantum propositions. Concretely, a mathematical framework
of a specific type of modal approach is extended to the topos theory, and further, structures of the obtained truth-value
valuations are investigated. What is taken up is the modal approach based on a determinate lattice
, which is a sublattice of the lattice
of all quantum propositions and is determined by a quantum state e and a preferred determinate observable R. Topos-theoretic extension is made in the functor category
of which base category
is determined by R. Each true atom, which determines truth values, true or false, of all propositions in
, generates also a multi-valued valuation function of which domain and range are
and a Heyting algebra given by the subobject classifier in
, respectively. All true propositions in
are assigned the top element of the Heyting algebra by the valuation function. False propositions including the null proposition
are, however, assigned values larger than the bottom element. This defect can be removed by use of a subobject semi-classifier.
Furthermore, in order to treat all possible determinate observables in a unified framework, another valuations are constructed
in the functor category
. Here, the base category
includes all
’s as subcategories. Although
has a structure apparently different from
, a subobject semi-classifier of
gives valuations completely equivalent to those in
’s. 相似文献
6.
C. Ruby A. Géhin R. Aissa J. Ghanbaja M. Abdelmoula J.-M. R. Génin 《Hyperfine Interactions》2006,167(1-3):803-807
Hydroxysulphate green rust species were precipitated in the presence of various anions. is stable at ∼pH 7 and is transformed into a mixture of magnetite and ferrous hydroxide when the pH raised at ∼12. In the
presence of carbonate species, is partially transformed into a mixture of magnetite and siderite at ∼pH 8.5. This transformation is stopped when silicate
anions are present in the solution. As already observed for phosphate anions, the adsorption of silicate anions on the lateral
faces of the crystals may explain this stabilization effect. Sulphate anions are easily exchanged by carbonate species at ∼pH 10.5. In
contrast, anionic exchange between sulphate and phosphate anions was not observed. 相似文献
7.
Paolo Aschieri Leonardo Castellani Marija Dimitrijević 《Letters in Mathematical Physics》2008,85(1):39-53
A -product is defined via a set of commuting vector fields , and used in a theory coupled to the fields. The -product is dynamical, and the vacuum solution , reproduces the usual Moyal product. The action is invariant under rigid translations and Lorentz rotations, and the conserved
energy–momentum and angular momentum tensors are explicitly derived.
相似文献
8.
The phenomenon of the diffusion of proton and deuteron in a single crystal of magnesium aluminate spinel was studied by infrared
absorption. The chemical diffusion coefficient of proton was determined by the relaxation time of the absorption intensity
upon the substitution of deuteron with proton. The temperature dependence of the chemical diffusion coefficient of proton
for was expressed as . The chemical diffusion coefficient of proton was found to be independent of the composition of spinel and of the atmosphere.
Paper presented at the 11th Euro Conference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15 2007. 相似文献
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Luc Haine 《Letters in Mathematical Physics》2006,76(2-3):269-282
We give a new proof of a classical result of Lagnese and Stellmacher, characterizing all Huygens’ operators of the form
, where q(x) depends on only one variable. The proof amounts to characterize the Schrödinger operators
with a finite heat kernel expansion. 相似文献
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Foias, Guillopé, & Temam showed in 1985 that for a given weak solution of the three-dimensional Navier-Stokes equations on a domain Ω, one can define a ‘trajectory mapping’ that gives a consistent choice of trajectory through each initial condition , and that respects the volume-preserving property one would expect for smooth flows. The uniqueness of this mapping is guaranteed
by the theory of renormalised solutions of non-smooth ODEs due to DiPerna & Lions.
However, this is a distinct question from the uniqueness of individual particle trajectories. We show here that if one assumes
a little more regularity for u than is known to be the case, namely that , then the particle trajectories are unique and C
1 in time for almost every choice of initial condition in Ω. This degree of regularity is more than can currently be guaranteed
for weak solutions () but significantly less than that known to ensure that u is regular ( . We rely heavily on partial regularity results due to Caffarelli, Kohn, & Nirenberg and Ladyzhenskaya & Seregin. 相似文献
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In this work, we investigate the thermal entanglement for interacting spin systems , by varying the parameters of temperature T, direction and magnetic field B.
PACS numbers: 03.67.Mn, 03.65.Ud, 05.30.Cd, 73.43.Nq 相似文献
14.
Local Asymptotic Normality in Quantum Statistics 总被引:1,自引:1,他引:0
The theory of local asymptotic normality for quantum statistical experiments is developed in the spirit of the classical result
from mathematical statistics due to Le Cam. Roughly speaking, local asymptotic normality means that the family consisting of joint states of n identically prepared quantum systems approaches in a statistical sense a family of Gaussian state ϕ
u
of an algebra of canonical commutation relations. The convergence holds for all “local parameters” such that parametrizes a neighborhood of a fixed point .
In order to prove the result we define weak and strong convergence of quantum statistical experiments which extend to the
asymptotic framework the notion of quantum sufficiency introduces by Petz. Along the way we introduce the concept of canonical
state of a statistical experiment, and investigate the relation between the two notions of convergence. For the reader’s convenience
and completeness we review the relevant results of the classical as well as the quantum theory.
Dedicated to Slava Belavkin on the occasion of his 60th anniversary 相似文献
15.
Asao Arai 《Letters in Mathematical Physics》2006,77(3):283-290
A quantum system of a Dirac particle interacting with the quantum radiation field is considered in the case where no external potentials exist. Then the total momentum of the system is conserved and the total Hamiltonian is unitarily equivalent to the direct integral
of a family of self-adjoint operators
acting in the Hilbert space
, where
is the Hilbert space of the quantum radiation field. The fiber operator
is called the Hamiltonian of the Dirac polaron with total momentum
. The main result of this paper is concerned with the non-relativistic (scaling) limit of
. It is proven that the non-relativistic limit of
yields a self-adjoint extension of a Hamiltonian of a polaron with spin 1/2 in non-relativistic quantum electrodynamics. 相似文献
16.
Zhi-Gang Wang 《The European Physical Journal C - Particles and Fields》2009,61(2):321-329
We calculate the masses and the pole residues of the
heavy baryons Ω
c
0(css) and Ω
b
−(bss) with the QCD sum rules. The numerical values
GeV (or
GeV) and
GeV (or
GeV) are in good agreement with the experimental data. 相似文献
17.
For a (co)monad T
l
on a category , an object X in , and a functor , there is a (co)simplex in . The aim of this paper is to find criteria for para-(co)cyclicity of Z
*. Our construction is built on a distributive law of T
l
with a second (co)monad T
r
on , a natural transformation , and a morphism in . The (symmetrical) relations i and w need to satisfy are categorical versions of Kaygun’s axioms of a transposition map. Motivation comes from the observation
that a (co)ring T over an algebra R determines a distributive law of two (co)monads and on the category of R-bimodules. The functor Π can be chosen such that is the cyclic R-module tensor product. A natural transformation is given by the flip map and a morphism is constructed whenever T is a (co)module algebra or coring of an R-bialgebroid. The notion of a stable anti-Yetter-Drinfel’d module over certain bialgebroids, the so-called ×
R
-Hopf algebras, is introduced. In the particular example when T is a module coring of a ×
R
-Hopf algebra and X is a stable anti-Yetter-Drinfel’d -module, the para-cyclic object Z
* is shown to project to a cyclic structure on . For a -Galois extension , a stable anti-Yetter-Drinfel’d -module T
S
is constructed, such that the cyclic objects and are isomorphic. This extends a theorem by Jara and Ştefan for Hopf Galois extensions. As an application, we compute Hochschild
and cyclic homologies of a groupoid with coefficients in a stable anti-Yetter-Drinfel’d module, by tracing it back to the
group case. In particular, we obtain explicit expressions for (coinciding relative and ordinary) Hochschild and cyclic homologies
of a groupoid. The latter extends results of Burghelea on cyclic homology of groups. 相似文献
18.
Marek Biskup Lincoln Chayes Shannon Starr 《Communications in Mathematical Physics》2007,269(3):611-657
We develop a novel approach to phase transitions in quantum spin models based on a relation to their classical counterparts. Explicitly, we show that whenever chessboard estimates can be used to prove a phase transition in the classical model, the corresponding quantum model will have a similar phase transition, provided the inverse temperature β and the magnitude of the quantum spins satisfy . From the quantum system we require that it is reflection positive and that it has a meaningful classical limit; the core technical estimate may be described as an extension of the Berezin-Lieb inequalities down to the level of matrix elements. The general theory is applied to prove phase transitions in various quantum spin systems with . The most notable examples are the quantum orbital-compass model on and the quantum 120-degree model on which are shown to exhibit symmetry breaking at low-temperatures despite the infinite degeneracy of their (classical) ground state. 相似文献
19.
Jonathan Weitsman 《Communications in Mathematical Physics》2008,277(1):101-125
We show how to construct measures on Banach manifolds associated to supersymmetric quantum field theories. These measures
are mathematically well-defined objects inspired by the formal path integrals appearing in the physics literature on quantum
field theory. We give three concrete examples of our construction. The first example is a family of measures on a space of functions on the two-torus, parametrized by a polynomial P (the Wess-Zumino-Landau-Ginzburg model). The second is a family of measures on a space of maps from to a Lie group (the Wess-Zumino-Novikov-Witten model). Finally we study a family of measures on the product of a space of connections on the trivial principal bundle with structure group G on a three-dimensional manifold M with a space of -valued three-forms on M.
We show that these measures are positive, and that the measures are Borel probability measures. As an application we show that formulas arising from expectations in the measures reproduce formulas discovered by Frenkel and Zhu in the theory of vertex operator algebras. We conjecture that a similar
computation for the measures , where M is a homology three-sphere, will yield the Casson invariant of M.
Dedicated to the memory of Raoul Bott
Supported in part by NSF grant DMS 04/05670. 相似文献
20.
Jürg Fröhlich B. Lars G. Jonsson Enno Lenzmann 《Communications in Mathematical Physics》2007,274(1):1-30
We study the nonlinear equation
which is known to describe the dynamics of pseudo-relativistic boson stars in the mean-field limit. For positive mass parameters,
m > 0, we prove existence of travelling solitary waves, , for some and with speed |v| < 1, where c = 1 corresponds to the speed of light in our units. Due to the lack of Lorentz covariance, such travelling solitary waves
cannot be obtained by applying a Lorentz boost to a solitary wave at rest (with v = 0). To overcome this difficulty, we introduce and study an appropriate variational problem that yields the functions as minimizers, which we call boosted ground states. Our existence proof makes extensive use of concentration-compactness-type
arguments.
In addition to their existence, we prove orbital stability of travelling solitary waves and pointwise exponential decay of in x. 相似文献