共查询到20条相似文献,搜索用时 31 毫秒
1.
Qiao-Yun Tan Lin Wang Jin-Xiang Li Jiao-Wen Tang Xin-Wen Wang 《International Journal of Theoretical Physics》2013,52(2):612-619
Taming decoherence is a critical issue in quantum information science. We here investigate amplitude-damping decoherence suppression of two-qubit entangled states by weak quantum measurements. It is shown that the weak measurements can effectively suppress the decoherence for different initial entangled states. More interestingly, we show that the weak measurements have different effects on the entanglement protection for two entangled states which are equivalent under a local unitary operation. This result implies that the entanglement protection effect could be modulated according to different demands. 相似文献
2.
Xi-Wen Hou Ming-Fang Wan Zhong-Qi Ma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,62(2):279-288
Various measures of entanglement have triggered considerable interest in the
relationship between entanglement measures and other
well-known quantities. As a demonstration, the dynamical
correlation of negativity and entropy is studied in two
coupled quartic oscillators for initial pure and mixed states that
are respectively taken to be the products and mixed density
matrices of coherent states and squeezed states on each
oscillator. The correlation with energy is also considered.
It is shown that for the initial pure states with a
small magnitude, two negativities are
positively correlated with the von Neumann entropy while they are anti-correlated with
the energy of each oscillator in the weak coupling regime. For mixed states
with a small magnitude the two negativities and the mutual entropy exhibit dominantly
positive correlation, whereas those three quantities are
dominantly anti-correlated with the sum of energies of two
oscillators in the case of weak interactions. Such correlation behaviors in the mixed
state with small magnitudes are most striking at the same step in
maximal and minimal values and in oscillation. The differences in
entropies and negativities between coherent states and squeezed
states are discussed. These are useful for quantum
entanglement and quantum information processing. 相似文献
3.
N. Gisin 《Foundations of Physics》1983,13(7):643-654
A model of dissipative quantum dynamics (with a nonlinear friction term) is applied to systems periodic in time. The model is compared with the standard approaches based on the Floquet theorem. It is shown that for weak frictions the asymptotic states of the dynamics we propose are the periodic steady states which are usually postulated to be the states relevant for the statistical mechanics of time-periodic systems. A solution to the problem of nonuniqueness of the “quasienergies” is proposed. The implication of a nonlinear evolution for Ludwig's axiomatization is briefly outlined. 相似文献
4.
The ground states of the ultracold spin-1 atoms trapped in a deep one-dimensional double-well optical superlattice in a weak magnetic field are obtained. It is shown that the ground-state diagrams of the reduced double- well model are remarkably different for the antiferromagnetic and ferromagnetic condensates. The transition between the singlet state and nematic state is observed for the antiferromagnetic interaction atoms, which can be realized by modulating the tunneling parameter or the quadratic Zeeman energy. An experiment to distinguish the different spin states is suggested. 相似文献
5.
It is shown that left-handed weak doublets with mixed states of charmed and ordinary quarks are important for overall explantions of recent weak phenomena, especially, ξvis distribution in dilepton production. 相似文献
6.
Grigoris Panotopoulos 《General Relativity and Gravitation》2010,42(7):1755-1764
Bound states of two weakly interactive massive particles are studied. It is assumed that the WIMPonium is formed due to the
gravitational interaction, since the weak interaction can sometimes be repulsive. The lifetimes of the spontaneous emission
of gravitational radiation and of the WIMPs annihilation into a pair of gravitons are computed, and are shown to be many orders
of magnitude larger than the age of the universe. 相似文献
7.
A simplified derivation of the macroscopic electrodynamic equations of Umezawa, Hancini et al. for superconductors is given in the framework of the closed time path Green's functions (CTPGF)using generalized Ward-Takahashi identities. It is shown that the forms of the equations obtained are the same for both thermoe quilibrium and nonequilibrium stationary states provided the electromagnetic field is weak and its effect on the modulus of the order parameter can be neglected. The statistical behavior of the states is completely specified in the equations by parameters which can be calculated by the method of CTPGF. 相似文献
8.
Dr. A. B. Govorkov 《International Journal of Theoretical Physics》1973,7(1):49-66
All irreducible separable representations of the non-relativistic para-Fermi field of order 3 in the configuration space are
considered. The existence of many different irreducible representations of the parafield permits us to interpret the excited
states of this field as the states of particles with internal degrees of freedom. These states can be labelled by the Young
patterns and the eigenvalues of internal quantum number like baryonic and hypercharges. The parafield theory is shown to be
equivalent to the theory of three kinds of ordinary ferminons, like quarks, and one of them, ‘strange’, can be distinguished
from the other two by means of its interaction, not only statistically but also dynamically. Thus the parafield theory is
shown to be equivalent to some model of the physicalSU (3) symmetry of hadrons when the strong and medium-strong interactions could be switched on but the electromagnetic and weak
interactions should be switched off. 相似文献
9.
10.
The Navier-Stokes systems for compressible fluids with density-dependent viscosities are considered in the present paper.
These equations, in particular, include the ones which are rigorously derived recently as the Saint-Venant system for the
motion of shallow water, from the Navier-Stokes system for incompressible flows with a moving free surface [14]. These compressible
systems are degenerate when vacuum state appears. We study initial-boundary-value problems for such systems for both bounded
spatial domains or periodic domains. The dynamics of weak solutions and vacuum states are investigated rigorously.
First, it is proved that the entropy weak solutions for general large initial data satisfying finite initial entropy exist
globally in time. Next, for more regular initial data, there is a global entropy weak solution which is unique and regular
with well-defined velocity field for short time, and the interface of initial vacuum propagates along the particle path during
this time period. Then, it is shown that for any global entropy weak solution, any (possibly existing) vacuum state must vanish
within finite time. The velocity (even if regular enough and well-defined) blows up in finite time as the vacuum states vanish.
Furthermore, after the vanishing of vacuum states, the global entropy weak solution becomes a strong solution and tends to
the non-vacuum equilibrium state exponentially in time. 相似文献
11.
Richard H. Herman 《Communications in Mathematical Physics》1972,28(3):237-243
It is shown, under a necessary condition, that strong (pointwise) convergence of modular automorphism groups to a one parameter family of maps implies weak convergence of the respective states in the factor case. Moreover the limiting one parameter family of maps is the modular automorphism group for the limiting state. In the type I case weak convergence of the automorphism groups suffices. Norm convergence of the states is obtained in some cases. 相似文献
12.
The ground state contributions to the leading high momentum behavior of the breakup amplitude of a composite system by a weak probe are shown to be exactly cancelled by final state interactions. The cancellation is a manifestation of the orthogonality of the target and continuum final states. The remaining large momentum behavior falls more rapidly and is more difficult to interpret directly in terms of properties of the target. 相似文献
13.
We present anisotropic thermal expansion measurements on single crystalline ErNi2B2C. All three, superconducting, antiferromagnetic and weak ferromagnetic phase transitions are unambiguously distinguished in the data. Anisotropic uniaxial pressure dependencies of the transitions are estimated based on the Ehrenfest relation, leading to a conclusion, in particular, that weak ferromagnetic states may be suppressed by small, order of few kbar, hydrostatic pressure. Additionally, magnetostriction is shown to be a useful probe for rich and complex H-T diagram in this material. 相似文献
14.
J. Mašek 《Zeitschrift für Physik B Condensed Matter》1986,64(2):145-150
The electronic states in a weak, spatially correlated disordered potential are investigated using a translationally invariant formalism within a tight binding model. The effect of the disorder is mapped intok-space. The influence of the statistical correlation on the density of states and their localization properties is studied in the one-dimensional limit. It is shown that clustering supports tail states while the middle of the band is strongly affected by rapidly alternating configurations. 相似文献
15.
The low temperature dependence of hopping conductivity σ(T) in 2d-DS with weak localization of electron states is investigated. Hopping between neighbouring localized states is suggested and a power law for σ(T) is obtained. Coulomb effects are shown to be negligible for this process. The transition from the logarithmic T dependence and to the exponential Mott's law is discussed. The density distribution of localized electron states is proved to be exponential. The dielectric permeability ?′(ω) is found to be proportional to |ω|?1 in the field of validity of the logarithmic corrections. 相似文献
16.
Johansen LM 《Physical review letters》2004,93(12):120402
The exact conditions on valid probe states for weak measurements are derived. It is demonstrated that weak measurements can be performed with any probe state with vanishing probability current density. This condition is found both for weak measurements of noncommuting observables and for c-number observables. In addition, the interaction between object and probe must be sufficiently weak. Strange weak values can be observed also with mixed probe states, but not for c-number observables. 相似文献
17.
It is shown that the convex set of classical states of the quantum harmonic oscillator is a simplex generated as the closed convex hull of the coherent states in the weak topology of the Banach space of trace class operators. 相似文献
18.
19.
Thermodynamic and transport characteristics of a clean two-dimensional interacting electron gas are shown to be sensitive to the weak perpendicular magnetic field even at temperatures much higher than the cyclotron energy, when the quantum oscillations are completely washed out. We demonstrate this sensitivity for two interaction-related characteristics: electron lifetime and the tunnel density of states. The origin of the sensitivity is traced to the field-induced smearing of the Kohn anomaly; this smearing is the result of curving of the semiclassical electron trajectories in magnetic field. 相似文献
20.
Derek W. Robinson 《Communications in Mathematical Physics》1970,19(3):219-234
It is shown that if \(\mathfrak{A}\) is an irreducibleC* algebra on a Hilbert space ? andN is the set of normal states of \(\mathfrak{A}\) then the weak and uniform topologies onN coincide and are identical to the weak*- \(\mathfrak{A}\) topology for each \(\mathfrak{A} \supset \mathfrak{L}\mathfrak{C}\) (?). It is further shown that all weak* topologies coincide with the uniform topology on the set of normal states with finite energy or with finite conditional entropy. A number of continuity properties of the spectra of density matrices, the mean energy, and the conditional entropy are also derived. The extension of these results to locally normal states is indicated and it is established that locally normal factor states are characterized by a doubly uniform clustering property. 相似文献