4,836 research outputs found
What is an elementary particle?
Schrödinger discusses what an elementary particle is. This essay originally appeared in the journal Endeavour
Entanglement in a first order quantum phase transition
The phase diagram of spins 1/2 embedded in a magnetic field mutually
interacting antiferromagnetically is determined. Contrary to the ferromagnetic
case where a second order quantum phase transition occurs, a first order
transition is obtained at zero field. The spectrum is computed for a large
number of spins and allows one to study the ground state entanglement
properties which displays a jump of its concurrence at the critical point.Comment: 4 pages, 3 EPS figure
Universal Measure of Entanglement
A general framework is developed for separating classical and quantum
correlations in a multipartite system. Entanglement is defined as the
difference in the correlation information encoded by the state of a system and
a suitably defined separable state with the same marginals. A generalization of
the Schmidt decomposition is developed to implement the separation of
correlations for any pure, multipartite state. The measure based on this
decomposition is a generalization of the entanglement of formation to
multipartite systems, provides an upper bound for the relative entropy of
entanglement, and is directly computable on pure states. The example of pure
three-qubit states is analyzed in detail, and a classification based on
minimal, four-term decompositions is developed.Comment: 4 page
Role of Bell Singlet State in the Suppression of Disentanglement
The stability of entanglement of two atoms in a cavity is analyzed in this
work. By studying the general Werner states we clarify the role of Bell-singlet
state in the problem of suppression of disentanglement due to spontaneous
emission. It is also shown explicitly that the final amount of entanglement
depends on the initial ingredients of the Bell-singlet state.Comment: 5 pages, 2 figures, accepted by Phys. Rev.
On the Asserted Clash between the Freud and the Bianchi Identities
Through a constructive method it is shown that the claim advanced in recent
times about a clash that should occur between the Freud and the Bianchi
identities in Einstein's general theory of relativity is based on a faulty
argument.Comment: 4 pages, plain Te
Uncertainty rescued: Bohr's complementarity for composite systems
Generalized uncertainty relations may depend not only on the commutator
relation of two observables considered, but also on mutual correlations, in
particular, on entanglement. The equivalence between the uncertainty relation
and Bohr's complementarity thus holds in a much broader sense than anticipated.Comment: Accepted for publication in Phys. Lett.
Exact solutions of a particle in a box with a delta function potential: The factorization method
We use the factorization method to find the exact eigenvalues and
eigenfunctions for a particle in a box with the delta function potential
. We show that the presence of the potential
results in the discontinuity of the corresponding ladder operators. The
presence of the delta function potential allows us to obtain the full spectrum
in the first step of the factorization procedure even in the weak coupling
limit .Comment: 8 pages, 2 figures, to appear in American Journal of Physic
Schr\"odinger uncertainty relation with Wigner-Yanase skew information
We shall give a new Schr\"odinger type uncertainty relation for a quantity
representing a quantum uncertainty, introduced by S.Luo in \cite{Luo1}. Our
result improves the Heisenberg uncertainty relation shown in \cite{Luo1} for a
mixed state.Comment: to appear in Phys.Rev.
- …