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1.
We derive a formula of the nonadiabatic noncyclic Pancharatnam phase for a mesoscopic circuit with coupled inductors and capacitors. It shows that, because of coupling effect, the circuit is in squeezed quantum state initially, and the time evolution of Pancharatnam phase exhibits an oscillation in a complex way. Especially we find that when the capacity of the coupled capacitors is larger than that of other ones in the circuit, with the variation of time Pancharatnam phase becomes nearly periodic square-wave, which perhaps can provide a new approach for the realization of quantum logic gate. 相似文献
2.
We derive a formula of the nonadiabatic noncyclic Pancharatnam phase for a mesoscopic circuit with coupled inductors and capacitors. It shows that,
because of coupling effect, the circuit is in squeezed quantum state initially, and the time evolution of Pancharatnam phase exhibits an oscillation in a complex way. Especially we find
that when the capacity of the coupled capacitors is larger than
that of other ones in the circuit, with the variation of time Pancharatnam
phase becomes nearly periodic square-wave, which perhaps can provide
a new approach for the realization of quantum logic gate. 相似文献
3.
4.
The Pancharatnam phase when an ideal cavity is filled with a Kerr-like medium and coupling is affected through a nondegenerate Raman two-photon process is studied. A careful investigation is made seeking exact results on the temporal evolution of atomic inversion and Pancharatnam phase. We invoke the mathematical notion of maximum variation of a function to construct a measure for Pancharatnam phase fluctuations. It is shown that Pancharatnam phase contains explicit information about the statistics of the field and atomic coherence, and is also shown that addition of the Kerr medium has an important effect on the properties of this phase. The results show that the effect of the Kerr medium changes the quasiperiod of the Pancharatnam phase evolution. The influence of Stark shift on the atomic inversion and the Pancharatnam phase in both presence and absence of the nonlinear medium is examined. General conclusions reached are illustrated by numerical results. 相似文献
5.
Bing Xie G. R. Zeng Hui Pan Zisheng Wang 《International Journal of Theoretical Physics》2016,55(3):1474-1491
The time-dependent Pancharatnam phase and the quantum correlations are studied for the two-qubit system in correlated dephasing environment. We find that in both X-state and Y-state, the rapid changes of the time-dependent Pancharatnam phase are intrinsic in the died and alive phenomena of quantum entanglement described by the concurrence under the exactly same parameters, while the slow changes of the time-dependent Pancharatnam phase correspond to the sudden death of entanglement. The results show that the time-dependent Pancharatnam phase includes the information of quantum correlations. 相似文献
6.
We consider a four-level atom (FLA) interacting with a field mode that is initially in a coherent state associated with a generalized Heisenberg algebra (CSGHA). The dynamical behavior of quantum entropy, the Pancharatnam phase, and the Mandel parameter are investigated. The statistical and nonclassical properties of the field in regard to its CSGHA are discussed through the evolution of the Mandel parameter, and the effects of the initial atomic state position and time-dependent coupling given in terms of atomic speed and acceleration are examined. The results show that the CSGHA strength and time-dependent coupling based on the atomic speed and acceleration have the potential to affect the time evolution of the entanglement, the Pancharatnam phase, and the Mandel parameter. 相似文献
7.
Nasser Metwally 《International Journal of Theoretical Physics》2008,47(3):623-633
A model of two 2-level atoms interacts with a single quantized electromagnetic field is considered. We study the effect of
the mean photon number and the structure of the initial states of the two atoms on the dynamics of the atomic system from
the separability point of view. It is found that, if we start from a product mixed atomic state, the probability of generating
long living entangled states is increased as the mean photon number increases. Starting from excited atomic system in product
state, one generates a more stable entangled states with high degree of entanglement. Also, the effect of the mean photon
number on atomic system prepared initially in entangled states is investigated. It is found that the entangled state generated
from the initially partial entangled states are more robust than those obtained from a maximum entangled state. The Pancharatnam
phase for the separable and entangled states is studied under the effect of the mean photon number and the structure of the
initial state. We find that for the separable states, the collapses decrease and the amplitude of the revivals is smaller
than that for the entangled state, so there are long-living entangled phases. This property give us a great chances to store
safely information in entangled state. 相似文献
8.
In mid-1950s, Pancharatnam [1] encountered the geometric phase associated with the evolution along a geodesic triangle on
the Poincaré sphere. We generalize his 3-vertex phase and employ it as the fundamental building block, to geometrically construct
a general ray-space expression for geometric phase. In terms of a reference ray used to specify geometric phase, we delineate
clear geometric meanings for gauge transformations and gauge freedom, which are generally regarded as mere mathematical abstractions. 相似文献
9.
简要介绍和评述了色味连锁物质的稳定态及其相变,指出高密强相互作用物质由于夸克配对出现了一些奇异相。重点介绍色味连锁(CFL)物质及其中的Goldstone-mode凝聚现象。在考虑奇异数对应化学势μs≠0的情况下,CFL物质中K^0和K^-0都可能发生凝聚。随着重子数密度的增高,强作用物质呈现出丰富相结构,在核物质相与CFL相之间可能存在其它相,但最简单的可能相变过程是直接从核物质相变为CFL物质。这种相变可有两种过程,即两相间仅存在一个极小界面或出现两相混合区域。另外还重点讨论了K^-介子凝聚对相变的影响。Quark matter at high density has a rich phase structure. Goidstone-mode may condense in the color-flavor-locked (CFL) phase matter. We review the stability of CFL phase and its phase transition, as well as the effect of nonzero strangeness chemical potential on the CFL phase of dense quark matter. It is pointed out that, depending on the value of μs, both K^0 and K^-0 may condense in the CFL matter. As a function of quark chemical potential, other phases may intervene between the nuclear-matter and CFL phase. The simplest possibility, however, is a transition between nuclear and CFL matter. Such a transition could occur either at a single sharp interface or through a mixed phase region. The effect of discontinuous K^- meson condensation on the phase transition is also discussed. [ 相似文献
10.
11.
R. J. Rivers 《International Journal of Theoretical Physics》2000,39(7):1779-1802
Kibble and Zurek have provided a unifying causal picture for the appearance ofclassical defects like cosmic strings or vortices at the onset of phase transitionsin relativistic QFT and condensed matter systems, respectively. In condensedmatter the predictions are partially supported by agreement with experiments insuperfluid helium. We provide an alternative picture for the initial appearanceof defects that supports the experimental evidence. When the original predictionsfail, this is understood, in part, as a consequence of thermal fluctuations (noise),which play a comparable role in both condensed matter and QFT. 相似文献
12.
For 1D continuous Schödinger operators with large analytic quasi-periodic potentials of two frequencies, one knows that the spectral measure is singular at the bottom of the spectrum and purely absolutely continuous in the upper part of the spectrum, so there is a phase transition when energy increases. In this paper, we obtain the exact power-law for the phase transition in energy by the semi-global reducibility theory of analytic quasi-periodic linear systems. 相似文献
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14.
Using the crystal structure prediction method based on particle swarm optimization algorithm, three phases(P nnm, C2/m and Pm-3 m) for InS are predicted. The new phase Pm-3m of InS under high pressure is firstly reported in the work. The structural features and electronic structure under high pressure of InS are fully investigated. We predicted the stable ground-state structure of InS was the P nnm phase and phase transformation of InS from P nnm phase to P m-3 m phase is firstly found at the pressure of about 29.5 GPa. According to the calculated enthalpies of InS with four structures in the pressure range from 20 GPa to 45 GPa, we find the C2/m phase is a metastable phase. The calculated band gap value of about 2.08 eV for InS with P nnm structure at 0 GPa agrees well with the experimental value. Moreover, the electronic structure suggests that the C2/m and P m-3m phase are metallic phases. 相似文献
15.
The main purpose of this paper is to introduce and establish basic results of a natural extension of the classical Boolean percolation model (also known as the Gilbert disc model). We replace the balls of that model by a positive non-increasing attenuation function \(l:(0,\infty ) \rightarrow [0,\infty )\) to create the random field \(\Psi (y)=\sum _{x\in \eta }l(|x-y|),\) where \(\eta \) is a homogeneous Poisson process in \({\mathbb {R}}^d.\) The field \(\Psi \) is then a random potential field with infinite range dependencies whenever the support of the function l is unbounded. In particular, we study the level sets \(\Psi _{\ge h}(y)\) containing the points \(y\in {\mathbb {R}}^d\) such that \(\Psi (y)\ge h.\) In the case where l has unbounded support, we give, for any \(d\ge 2,\) a necessary and sufficient condition on l for \(\Psi _{\ge h}(y)\) to have a percolative phase transition as a function of h. We also prove that when l is continuous then so is \(\Psi \) almost surely. Moreover, in this case and for \(d=2,\) we prove uniqueness of the infinite component of \(\Psi _{\ge h}\) when such exists, and we also show that the so-called percolation function is continuous below the critical value \(h_c\). 相似文献
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17.
Structural behaviour of cyclo-octane under high pressure is studied by using a synchrotron x-ray source in a diamond anvil cell (DAC) up to 40.2 GPa at room temperature. The cyclo-octane firstly solidifies to the triclinic phase at 0.87 GPa. With the increasing pressure, the phase of cyclo-octane changes to the tetragonal phase at about 6.0 GPa and then transforms to amorphous phase above 18.2 GPa, which is kept till to 40.2 GPa. All the phase transitions of cyclo-octane are irreversible. 相似文献
18.
We analyze the Farey spin chain, a one-dimensional spin system with long-range multibody interactions. Using a polymer model technique, we show that when the temperature is decreased below the (single) critical temperature T
c=1/2, the magnetization jumps from zero to one. 相似文献
19.
Based on the first-principles calculations, we firstly predict that RuB2 undergoes a phase transition from the orthorhombic phase to the hexagonal phase with a volume collapse of 1% when the applied pressure is 15. 7 GPa. The values of calculated elastic moduli indicate that RuB2 and RuN2 are low compressibility materials. Based on the calculated electronic density of states and valence charge density distribution, the bonding nature of RuB2 is examined to obtain a deeper insight into the physical origin of the mechanical properties. The metallieity and high elastic moduli of RuB2 and FuN2 suggest that they axe potential hard conductors. 相似文献
20.
S. Abdel-Khalek K. Berrada Y. S. El-Saman M. Abdel-Aty 《Journal of Russian Laser Research》2012,33(5):437-447
We study the time evolution of the total and Pancharatnam phase of four-level atoms in the presence of a one-dimensional photonic-band-gap material. We obtain analytical and numerical results under certain parametric conditions and analyze the effect of a Kerr-like medium and the detuning parameter on the dynamics of the Pancharatnam phase for the initial atomic position. We observe an interesting feature of the Pancharatnam phase for the one-dimensional photonic-band-gap material. 相似文献