142,472 research outputs found
Tidal wave in 102Pd: Rotating condensate of up to seven d-bosons
The yrast states of even even vibrational and transitional nuclei are inter-
preted as a rotating condensate of interacting d-bosons and the corresponding
semi-classical tidal wave concept. A simple experimental manifestation of the
anharmonicity caused by the boson interaction is found. The interpretation is
substantiated by calculations based on the Collective Model and the Cranking
Model.Comment: Proceedings of CGS1
An quantum approach of measurement based on the Zurek's triple model
In a close form without referring the time-dependent Hamiltonian to the total
system, a consistent approach for quantum measurement is proposed based on
Zurek's triple model of quantum decoherence [W.Zurek, Phys. Rev. D 24, 1516
(1981)]. An exactly-solvable model based on the intracavity system is dealt
with in details to demonstrate the central idea in our approach: by peeling off
one collective variable of the measuring apparatus from its many degrees of
freedom, as the pointer of the apparatus, the collective variable de-couples
with the internal environment formed by the effective internal variables, but
still interacts with the measured system to form a triple entanglement among
the measured system, the pointer and the internal environment. As another
mechanism to cause decoherence, the uncertainty of relative phase and its
many-particle amplification can be summed up to an ideal entanglement or an
Shmidt decomposition with respect to the preferred basis.Comment: 22pages,3figure
Disentanglement in a quantum critical environment
We study the dynamical process of disentanglement of two qubits and two
qutrits coupled to an Ising spin chain in a transverse field, which exhibits a
quantum phase transition. We use the concurrence and negativity to quantify
entanglement of two qubits and two qutrits, respectively. Explicit connections
between the concurrence (negativity) and the decoherence factors are given for
two initial states, the pure maximally entangled state and the mixed Werner
state. We find that the concurrence and negativity decay exponentially with
fourth power of time in the vicinity of critical point of the environmental
system.Comment: 8 pages, 6 figure
High-Order Adiabatic Approximation for Non-Hermitian Quantum System and Complexization of Berry's Phase
In this paper the evolution of a quantum system drived by a non-Hermitian
Hamiltonian depending on slowly-changing parameters is studied by building an
universal high-order adiabatic approximation(HOAA) method with Berry's phase
,which is valid for either the Hermitian or the non-Hermitian cases. This
method can be regarded as a non-trivial generalization of the HOAA method for
closed quantum system presented by this author before. In a general situation,
the probabilities of adiabatic decay and non-adiabatic transitions are
explicitly obtained for the evolution of the non-Hermitian quantum system. It
is also shown that the non-Hermitian analog of the Berry's phase factor for the
non-Hermitian case just enjoys the holonomy structure of the dual linear bundle
over the parameter manifold. The non-Hermitian evolution of the generalized
forced harmonic oscillator is discussed as an illustrative examples.Comment: ITP.SB-93-22,17 page
Substrate effects on quasiparticles and excitons in graphene nanoflakes
The effects of substrate on electronic and optical properties of triangular
and hexagonal graphene nanoflakes with armchair edges are investigated by using
a configuration interaction approach beyond double excitation scheme. The
quasiparticle correction to the energy gap and exciton binding energy are found
to be dominated by the long-range Coulomb interactions and exhibit similar
dependence on the dielectric constant of the substrate, which leads to a
cancellation of their contributions to the optical gap. As a result, the
optical gaps are shown to be insensitive to the dielectric environment and
unexpectedly close to the single-particle gaps.Comment: 4 pages, 4 figure
Visual attributes of subliminal priming images impact conscious perception of facial expressions
We investigated, in young healthy participants, how the affective content of subliminally presented priming images and their specific visual attributes impacted conscious perception of facial expressions. The priming images were broadly categorized as aggressive, pleasant, or neutral and further subcategorized by the presence of a face and by the centricity (egocentric or allocentric vantage-point) of the image content. Participants responded to the emotion portrayed in a pixelated target-face by indicating via key-press if the expression was angry or neutral. Response time to the neutral target face was significantly slower when preceded by face primes, compared to non-face primes (p < 0.05, Bonferroni corrected). In contrast, faster RTs were observed when angry target faces were preceded by face compared to non-face primes. In addition, participants’ performance was worse when a priming image contained an egocentric face compared to when it contained either an allocentric face or an egocentric non-face. The results suggest a significant impact of the visual features of the priming image on conscious perception of face expression.Published versio
Quantum Dynamical Model for Wave Function Reduction in Classical and Macroscopic Limits
In this papper, a quantum dynamical model describing the quantum measurement
process is presented as an extensive generalization of the Coleman-Hepp model.
In both the classical limit with very large quantum number and macroscopic
limit with very large particle number in measuring instrument, this model
generally realizes the wave packet collapse in quantum measurement as a
consequence of the Schrodinger time evolution in either the exactly-solvable
case or the non-(exactly-)solvable case.
For the latter, its quasi-adiabatic case is explicitly analysed by making use
of the high-order adiabatic approximation method and then manifests the wave
packet collapse as well as the exactly-solvable case. By highlighting these
analysis, it is finally found that an essence of the dynamical model of wave
packet collapse is the factorization of the Schrodinger evolution other than
the exact solvability. So many dynamical models including the well-known ones
before, which are exactly-solvable or not, can be shown only to be the concrete
realizations of this factorizabilityComment: ITP.SB-93-14,19 page
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