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831.
The time evolution of the field quantum entropy and entanglement in a system of multi-mode coherent light field resonantly
interacting with a two-level atom by degenerating the multi-photon process is studied by utilizing the Von Neumann reduced
entropy theory, and the analytical expressions of the quantum entropy of the multimode field and the numerical calculation
results for three-mode field interacting with the atom are obtained. Our attention focuses on the discussion of the influences
of the initial average photon number, the atomic distribution angle and the phase angle of the atom dipole on the evolution
of the quantum field entropy and entanglement. The results obtained from the numerical calculation indicate that: the stronger
the quantum field is, the weaker the entanglement between the quantum field and the atom will be, and when the field is strong
enough, the two subsystems may be in a disentangled state all the time; the quantum field entropy is strongly dependent on
the atomic distribution angle, namely, the quantum field and the two-level atom are always in the entangled state, and are
nearly stable at maximum entanglement after a short time of vibration; the larger the atomic distribution angle is, the shorter
the time for the field quantum entropy to evolve its maximum value is; the phase angles of the atom dipole almost have no
influences on the entanglement between the quantum field and the two-level atom. Entangled states or pure states based on
these properties of the field quantum entropy can be prepared. 相似文献
832.
A procedure using gas chromatography and tandem mass spectrometry (GC-MS-MS) has been developed for the identification and quantification of some allelochemicals in wheat (Triticum aestivum L.). The quantities of allelochemicals in wheat shoots ranged from 2.9 to 110 mg per kilogram of dry shoot residues. Compared with gas chromatography-mass spectrometry (GC-MS), the GC-MS-MS technique significantly increased instrument selectivity and sensitivity, thereby providing more reliable quantitation results in the determination of the phytotoxic compounds examined during this allelopathy research. 相似文献
833.
We predict the existence of a new pulsed-laser operation regime, when the phases and polarizations of the two coupled cold-cavity eigenstates of a monomode solid-state laser are taken into account in the derivation of the Maxwell-Bloch equations. This monomode pulsed regime is experimentally observed, without any normal mode locking or Q switching occurring inside the cavity. We obtain close agreement between experiments and theory, even in the simple case of a Nd:YAG microchip laser, for which sech(2) pulses at nearly megahertz repetition rates are readily observed. 相似文献
834.
Pierre-yves Le Gall 《K-Theory》1999,16(4):361-390
Let
be a locally compact topological groupoid, A and B two C*-algebras endowed with a continuous action of
. We define an operator K-theory group K K
(A,B). We describe two basic properties of this theory: the existence of a Kasparov product and functoriality with respect to groupoid cocycles. 相似文献
835.
Maohua Le 《Transactions of the American Mathematical Society》1999,351(3):1063-1074
In this paper we prove that the equation , , , , , has only the solutions and with is a prime power. The proof depends on some new results concerning the upper bounds for the number of solutions of the generalized Ramanujan-Nagell equations.
836.
Qinghua Zhao Thi Tuyet Mai Dang Dong‐Cheol Shin Hong You Soon‐Ki Kwon 《Journal of polymer science. Part A, Polymer chemistry》2007,45(3):341-347
Diphenylaminobiphenylated stryl based alternating copolymers with phenyl or fluorene, which were expected to have a terphenylene vinylene backbone containing an (N,N‐diphenylamino)biphenyl pendant and a phenyl/fluorene/phenylene vinylene backbone containing an (N,N‐diphenylamino)biphenyl pendant, were synthesized by a Suzuki coupling reaction. The obtained copolymers were confirmed with various types of spectroscopy. The alternating copolymers showed good hole‐injection properties because of their low oxidation potential and good solubility and high thermal stability with a high glass‐transition temperature. The alternating copolymers showed blue emissions because of the adjusted conjugation lengths; the maximum wavelength was 460 nm for poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl]vinylene‐alt‐5‐(2′‐ethylhexyloxy)‐2‐methoxybenzene} and 487 nm for poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl] vinylene‐alt‐9,9‐dihexylfluorene}. The maximum brightness of indium tin oxide/poly(3,4‐ethylene dioxythiophene)/polymer/LiF/Al devices with poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl]vinylene‐alt‐5‐(2′‐ethylhexyloxy)‐2‐methoxybenzene} or poly{4,4′‐biphenylene‐α‐[4″‐(N,N′‐diphenylamino)diphenyl]vinylene‐alt‐9,9‐dihexylfluorene} as the emitting layer was 250 or 1000 cd/m2, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 341–347, 2007 相似文献
837.
给出了在常见的函数内积下任意两个零阶贝塞尔函数的内积公式,进而证明了由第一类和第二类零阶贝塞尔函数的线性函数族的正交性以及长度的表达式. 相似文献
838.
Cao An Wang 《BIT Numerical Mathematics》1991,31(2):230-236
An algorithm for finding a polygon with minimum number of edges nested in two simplen-sided polygons is presented. The algorithm solves the problem in at mostO(n logn) time, and improves the time complexity of two previousO(n
2) algorithms.The work was supported by NSERC grant OPG0041629. 相似文献
839.
840.
Huiling Le 《Probability Theory and Related Fields》1996,106(1):137-149
Summary. Suppose that M is a complete, simply connected Riemannian manifold of non-positive sectional curvature with dimension m ≧ 3. If, outside a fixed compact set, the sectional curvatures are bounded above by a negative constant multiple of the inverse
of the square of the geodesic distance from a fixed point and below by another negative constant multiple of the square of
the geodesic distance, then the angular part of Brownian motion on M tends to a limit as time tends to infinity, and the closure of the support of the distribution of this limit is the entire
S
m−1
. This improves a result of Hsu and March.
Received: 7 December 1994/In revised form: 2 September 1995 相似文献