4,770 research outputs found
Quantum Interpretations
Difficulties and discomfort with the interpretation of quantum mechanics are
due to differences in language between it and classical physics. Analogies to
The Special Theory of Relativity, which also required changes in the basic
worldview and language of non-relativistic classical mechanics, may help in
absorbing the changes called for by quantum physics. There is no need to invoke
extravagances such as the many worlds interpretation or specify a central role
for consciousness or neural microstructures. The simple, but basic, acceptance
that what is meant by the state of a physical system is different in quantum
physics from what it is in classical physics goes a long way in explaining its
seeming peculiarities.Comment: 13 page
1, 2, and 6 qubits, and the Ramanujan-Nagell theorem
A conjecture of Ramanujan that was later proved by Nagell is used to show on
the basis of matching dimensions that only three -qubit systems, for , can share an isomorphism of their symmetry groups with the rotation
group of corresponding dimensions . Topological analysis, however,
rules out the last possibility
Complete time-dependent treatment of a three-level system
Both unitary evolution and the effects of dissipation and decoherence for a
general three-level system are of widespread interest in quantum optics,
molecular physics, and elsewhere. A previous paper presented a technique for
solving the time-dependent operator equations involved but under certain
restrictive conditions. We now extend our results to a general three-level
system with arbitrary time-dependent Hamiltonians and Lindblad operators.
Analytical handling of the SU(3) algebra of the eight operators involved leaves
behind a set of coupled first-order differential equations for classical
functions. Solution of this set gives a complete solution of the quantum
problem, without having to invoke rotating-wave or other approximations.
Numerical illustrations are given.Comment: 1 tar.gz file containing a Tex and four eps figure files; unzip with
command gunzip RZPRA05.tar.g
Sudden change in dynamics of genuine multipartite entanglement of cavity-reservoir qubits
We study the dynamics of genuine multipartite entanglement for a system of
four qubits. Using a computable entanglement monotone for multipartite systems,
we investigate the as yet unexplored aspects of a cavity-reservoir system of
qubits. For one specific initial state, we observe a sudden transition in the
dynamics of genuine entanglement for the four qubits. This sudden change occurs
only during a time window where neither cavity-cavity qubits nor
reservoir-reservoir qubits are entangled. We show that this sudden change in
dynamics of this specific state is extremely sensitive to white noise.Comment: 18 pages, 11 figure
Generalized X states of N qubits and their symmetries
Several families of states such as Werner states, Bell-diagonal states and
Dicke states are useful to understand multipartite entanglement. Here we
present a [2^(N+1)-1]-parameter family of N-qubit "X states" that embrace all
those families, generalizing previously defined states for two qubits. We also
present the algebra of the operators that characterize the states and an
iterative construction for this algebra, a sub-algebra of su(2^(N)). We show
how a variety of entanglement witnesses can detect entanglement in such states.
Connections are also made to structures in projective geometry.Comment: 4 pages, 2 figure
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