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991.
We study ergodic averages for a class of pseudodifferential operators on the flatN-dimensional torus with respect to the Schrödinger evolution. The later can be consider a quantization of the geodesic flow on
. We prove that, up to semi-classically negligible corrections, such ergodic averages are translationally invariant operators.Mathematics Subject Classifications (2000) 58J50, 58J40, 81S10. 相似文献
992.
Implementation of a multiple round quantum dense coding using nuclear magnetic resonance 总被引:1,自引:0,他引:1
Zhang?Jingfu?Email author Xie?Jingyi Wang?Chuan Deng?Zhiwei Lu?Zhiheng Long?Guilu 《中国科学G辑(英文版)》2005,48(6):706-715
~~Implementation of a multiple round quantum dense coding using nuclear magnetic resonance1. Bennett, C. H., Wiesner, S. J., Communication via one- and two-particle operators on Einstein-Podolsky-Rosen states, Phys. Rev. Lett., 1992, 69(20): 2881-2884.
2. Mattle, K., Weinfurter, H., Kwiat, P. G. et al., Dense coding in experimental quantum communication, Phys. Rev. Lett., 1996, 76(25): 4656-4659.
3. Fang, X. M., Zhu, X. W., Feng, M. et al., Experimental implementation of dens… 相似文献
993.
994.
Ya-Jun Gao 《General Relativity and Gravitation》2005,37(1):1-17
A so-called extended elliptical-complex (EEC) function method is proposed and used to further study the Einstein–Maxwell-dilaton-axion theory with p vector fields (EMDA-p theory, for brevity) for
. An Ernst-like
matrix EEC potential is introduced and the motion equations of the stationary axisymmetric EMDA-p theory are written as a so-called Hauser–Ernst-like self-dual relation for the EEC matrix potential. In particular, for the EMDA-2 theory, two Hauser–Ernst-type EEC linear systems are established and based on their solutions some new parametrized symmetry transformations are explicitly constructed. These hidden symmetries are verified to constitute an infinite-dimensional Lie algebra, which is the semidirect product of the Kac–Moody algebra
and Virasoro algebra (without centre charges). These results show that the studied EMDA-p theories possess very rich symmetry structures and the EEC function method is necessary and effective. 相似文献
995.
Michael?HellerEmail author Leszek?Pysiak Wies?w?Sasin 《International Journal of Theoretical Physics》2005,44(6):619-628
We continue our program of unifying general relativity and quantum mechanics in terms of a noncommutative algebra А on a transformation groupoid Γ = E × G where E is the total space of a principal fibre bundle over spacetime, and G a suitable group acting on Γ . We show that every a ∊ А defines a random operator, and we study the dynamics of such operators. In the noncommutative regime, there is no usual time but, on the strength of the Tomita–Takesaki theorem, there exists a one-parameter group of automorphisms of the algebra А which can be used to define a state dependent dynamics; i.e., the pair (А, ϕ), where ϕ is a state on А, is a “dynamic object.” Only if certain additional conditions are satisfied, the Connes–Nikodym–Radon theorem can be applied and the dependence on ϕ disappears. In these cases, the usual unitary quantum mechanical evolution is recovered. We also notice that the same pair (А, ϕ) defines the so-called free probability calculus, as developed by Voiculescu and others, with the state ϕ playing the role of the noncommutative probability measure. This shows that in the noncommutative regime dynamics and probability are unified. This also explains probabilistic properties of the usual quantum mechanics. 相似文献
996.
Lev?B.?Levitin Tom?ToffoliEmail author Zac?Walton 《International Journal of Theoretical Physics》2005,44(2):219-228
We consider a fixed quantum measurement performed over n identical copies of quantum states. Using a rigorous notion of distinguishability based on Shannon’s 12th theorem, we show that in the case of a single qubit, the number of distinguishable states is
, where (α1,α2) is the angle interval from which the states are chosen. In the general case of an N-dimensional Hilbert space and an area Ω of the domain on the unit sphere from which the states are chosen, the number of distinguishable states is
. The optimal distribution is uniform over the domain in Cartesian coordinates. 相似文献
997.
Quantum systems with quadratic Hamiltonians are considered. Some results about the time evolution of homogeneous polynomials and of quantum correlation functions are given. The image of arbitrary orbit of Weyl–Heisenberg group under this time evolution is shown to be again an orbit of this group. For quantum free particle it is shown that its time evolution intersects arbitrary such orbit at most once. A result about existence of more orbits having the same dispersion of some quantum position is presented.PACS: 02.20.Qs, 02.30.Sa 相似文献
998.
Chang-yong?ChenEmail author Ke-lin?Gao 《International Journal of Theoretical Physics》2005,44(8):1177-1191
The physics realization of a ququadrit quantum computation with cooled trapped 138Ba+ ions in a Paul trap is investigated. The ground state level 62 S1/2(m = −1/2) and three metastable levels: 52 D3/2(m = −1/2), 52 D5/2(m = −1/2), and 52 D5/2(m = 1/2), of the fine-structure of the 138Ba+ ion, are used to store the quantum information of ququadrits. The use of coherent manipulation of populations in single ququadrit,
being a four-dimensional Hilbert space, produces a discrete Fourier transform and the manipulation of the first red band transitions
with the introduction of an ancillary quantum channel between two ququadrits generates a conditional phase gate. The combination
of the both above results in a universal two-ququadrit gate, called XOR(4) gate corresponding to the controlled-NOT gate operation in qubit systems. The implementation of quantum Fourier transform
for n ququadrits is performed by means of the conditional phase-shift gate. The feasibility of physical realization of ququadrit
quantum computation with cooled-trapped 138Ba+ ions is detailed analyzed and described, and the theoretical detection method of logical states is given. Higher entanglement
between ququadrits than qutrits or qubits and more security of ququadrit quantum cryptography than qutrit's or qutrit's will
lead to more extensive applications ququadrits in quantum information fields. In particular, it is pointed out that this scheme
should be the highest dimensional quantum computation in cooled-trapped ions, the entanglement between ququadrits should be
the highest dimensional entanglement in it, and the ququadrit quantum cryptography should be the most secure cryptography
protocol in it. 相似文献
999.
In this paper, we introduce a map between the q-deformed gauge fields defined on the GLq(N) -covariant quantum hyperplane and the ordinary gauge fields. Perturbative analysis of the q-deformed QED at the classical level is presented and gauge fixing à la BRST is discussed. Another star product defined on the hybrid (q,h) -plane is explicitly constructed. 相似文献
1000.
In this paperwewill derive a generalized uncertainty principle (GUP) in a simple varying speed of light (VSL) model. First
we will show that VSL is an immediate consequence of GUP. Then, within the framework of a simple VSL model, we will show that
GUP can be expressed as a function of cosmological scale factor. This expression gives two main results: uncertainties in
position and momentum are actually cosmological models dependent and these uncertainties depend on mass and momentum of the
particle under consideration. The relationship between matter content of the Universe and the values of uncertainties in early
stages of the evolution of the Universe will be discussed in a mini-superspace approach. 相似文献