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31.
T. Bergmann T. Gasenzer O. Nachtmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):211-227
We discuss and calculate parity conserving (PC) and parity violating (PV) geometric phases for the metastable 2S states of
hydrogen and deuterium. The atoms are supposed to be subjected to slowly varying electric and magnetic fields which act as
external parameters for the atoms. Geometric flux density fields are introduced which allow for an easy overview how to choose
the paths in parameter space in order to obtain only PC or only PV geometric phases. The PV phases are calculated in the Standard
Model of particle physics. Even if numerically they come out small they have interest of principle as a new manifestation
of parity violation in atomic physics.
Electronic supplementary material Supplementary Online Material 相似文献
32.
H. T. Cui L. C. Wang X. X. Yi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):385-389
The geometric phase (GP) for bipartite systems in transverse
external magnetic fields is investigated in this paper. Two
different situations have been studied. We first consider two
non-interacting particles. The results show that because of
entanglement, the geometric phase is very different from that of the
non-entangled case. When the initial state is a Werner state, the
geometric phase is, in general, zero and moreover the singularity of
the geometric phase may appear with a proper evolution time.
We next study the
geometric phase when intra-couplings appear and choose Werner
states as the initial states to entail this discussion. The results
show that unlike our first case, the absolute value of the GP is not zero,
and attains its maximum when the rescaled coupling
constant J is less than 1. The effect of inhomogeneity of the
magnetic field is also discussed. 相似文献
33.
M.-M. He G. Chen J.-Q. Liang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):581-583
In this paper we investigate the Berry phase in Tavis-Cummings model in the
rotating wave approximation. The dipole-dipole interaction between the atoms
is considered. The eigenfunctions of the system are obtained and thus the
Berry phase is evaluated explicitly in terms of the introduction of the
phase shift. It is shown that the Berry phase can be easily controlled by
the atom-cavity coupling strength, the cavity frequency detuning, which can
be important in applications in geometric quantum computing. 相似文献
34.
P. Gosselin A. Bérard H. Mohrbach 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(2):137-148
It has been recently found that the equations of motion of several
semiclassical systems must take into account terms arising from Berry phases
contributions. Those terms are responsible for the spin Hall effect in
semiconductor as well as the Magnus effect of light propagating in
inhomogeneous media. Intensive ongoing research on this subject seems to
indicate that a broad class of quantum systems may be affected by Berry
phase terms. It is therefore important to find a general procedure allowing
for the determination of semiclassical Hamiltonian with Berry Phase
corrections. This article presents a general diagonalization method at order
ħ for a large class of quantum Hamiltonians directly inducing Berry
phase corrections. As a consequence, Berry phase terms on both coordinates
and momentum operators naturally arise during the diagonalization procedure.
This leads to new equations of motion for a wide class of semiclassical
system. As physical applications we consider here a Dirac particle in an
electromagnetic or static gravitational field, and the propagation of a
Bloch electrons in an external electromagnetic field. 相似文献
35.
Films of (Cd-Pb)S have been prepared using chemical deposition in aqueous alkaline bath and their subsequent condensation on substrates. Important achievements in terms of electrical response, optical absorption and photoconductivity (PC) excitation spectra, SEM, XRD and photoluminescence (PL) studies are presented and discussed. From the photocurrent curves, the ratio I PC (saturated photocurrent)/I DC (dark current) was observed to be of the order of 106 for the systems prepared with CdCl2, and to be 107 when doped with samarium nitrate. Values of trap depth E, lifetime and mobility are evaluated from the PC decay. Band gaps are determined from the two spectra. Diffraction lines in XRD studies are associated with CdS and PbS, and according to SEM studies, layered growth of the films takes place. PL of samarium-doped (Cd-Pb)S films shows an emission peak in the green-yellow region under 365-nm excitation. The PL brightness decreases with temperature. 相似文献
36.
37.
H. T. Cui Y. F. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):393-400
The pairwise entanglement, measured by concurrence and
geometric phase in high dimensional free-Fermion lattice systems
have been studied in this paper. When the system stays at the ground
state, their derivatives with the external parameter show the
singularity closed to the phase transition points, and can be used
to detect the phase transition in this model. Furthermore our
studies show for the free-Fermion model that both concurrence and
geometric phase show the intimate connection with the correlation
functions. The possible connection between concurrence and geometric
phase has been also discussed. 相似文献
38.
J. Prikryl M. Hrdlicka M. Frumar J. Orava L. Benes M. Vlcek P. Kostal L. Hromadko T. Wagner 《Journal of Non》2009,355(37-42):1998-2002
The crystalline samples of Ge4Sb4Te10, Ge4Sb4Te9, and Ge4Sb4Te8 were prepared and their amorphous semiconducting thin films obtained by flash evaporation. Their sheet resistance decreased slowly with temperature up to 147–160 °C with activation energy of electrical conductivity ΔE = 0.40–0.44 eV. Above these temperatures, the sheet resistance drops abruptly by several orders due to crystallization. The drop of resistivity proceeds in two steps. Two steps of phase change were also found on curves of DSC and on the temperature dependence of index of refraction. It pays for slow heating rates, crystallization induced by short (≈30 ns) laser pulses proceeds probably in one step only for all studied samples (as it follows from X-ray diffraction), not only for Ge2Sb2Te5 in which a single phase formation was confirmed. The crystallization temperatures are increasing slightly with decreasing Te content in the series Ge4Sb4Te10–Ge4Sb4Te9–Ge4Sb4Te8 from 147 to 160 °C. The X-ray diffractograms revealed that in laser crystallized samples can be found only cubic modification of Ge2Sb2Te5 type (a = 0.6 nm), while the samples annealed (230 °C, 2 h) or annealed after the crystallization with laser pulse, contain also small amounts of hexagonal phase. 相似文献
39.
M. P. Trushin A. L. Chudnovskiy 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):547-555
We have found a manifestation of spin-orbit Berry phase in the conductance
of a mesoscopic loop with Rashba spin-orbit coupling placed in an external magnetic field
perpendicular to the loop plane.
In detail, the transmission probabilities for a straight quantum wire
and for a quantum loop made of the same wire have been calculated and
compared with each other.
The difference between them has been investigated and identified with
a manifestation of spin-orbit Berry phase.
The non-adiabaticity effects at small radii of the loop have been found as well. 相似文献
40.
In this work we summarize the results of first-principles theoretical studies of the sequence of pressure-driven phase-transitions followed by the group-IVa elements Si and Ge. The agreement with the available experimental data is very good. 相似文献