8,117 research outputs found
Quantum Disentangled Liquids
We propose and explore a new finite temperature phase of translationally
invariant multi-component liquids which we call a "Quantum Disentangled Liquid"
(QDL) phase. We contemplate the possibility that in fluids consisting of two
(or more) species of indistinguishable quantum particles with a large mass
ratio, the light particles might "localize" on the heavy particles. We give a
precise, formal definition of this Quantum Disentangled Liquid phase in terms
of the finite energy density many-particle wavefunctions. While the heavy
particles are fully thermalized, for a typical fixed configuration of the heavy
particles, the entanglement entropy of the light particles satisfies an area
law; this implies that the light particles have not thermalized. Thus, in a QDL
phase, thermal equilibration is incomplete, and the canonical assumptions of
statistical mechanics are not fully operative. We explore the possibility of
QDL in water, with the light proton degrees of freedom becoming "localized" on
the oxygen ions. We do not presently know whether a local, generic Hamiltonian
can have eigenstates of the QDL form, and if it can not, then the non-thermal
behavior discussed here will exist as an interesting crossover phenomena at
time scales that diverge as the ratio of the mass of the heavy to the light
species also diverges.Comment: 14 page
Quantum search algorithms on a regular lattice
Quantum algorithms for searching one or more marked items on a d-dimensional
lattice provide an extension of Grover's search algorithm including a spatial
component. We demonstrate that these lattice search algorithms can be viewed in
terms of the level dynamics near an avoided crossing of a one-parameter family
of quantum random walks. We give approximations for both the level-splitting at
the avoided crossing and the effectively two-dimensional subspace of the full
Hilbert space spanning the level crossing. This makes it possible to give the
leading order behaviour for the search time and the localisation probability in
the limit of large lattice size including the leading order coefficients. For
d=2 and d=3, these coefficients are calculated explicitly. Closed form
expressions are given for higher dimensions
Quantum Mechanics helps in searching for a needle in a haystack
Quantum mechanics can speed up a range of search applications over unsorted
data. For example imagine a phone directory containing N names arranged in
completely random order. To find someone's phone number with a probability of
50%, any classical algorithm (whether deterministic or probabilistic) will need
to access the database a minimum of O(N) times. Quantum mechanical systems can
be in a superposition of states and simultaneously examine multiple names. By
properly adjusting the phases of various operations, successful computations
reinforce each other while others interfere randomly. As a result, the desired
phone number can be obtained in only O(sqrt(N)) accesses to the database.Comment: Postscript, 4 pages. This is a modified version of the STOC paper
(quant-ph/9605043) and is modified to make it more comprehensible to
physicists. It appeared in Phys. Rev. Letters on July 14, 1997. (This paper
was originally put out on quant-ph on June 13, 1997, the present version has
some minor typographical changes
Circular 99
We initiated this study to develop a single small
scale boiling tank and test a drying technique on samples of velvet antler
Observation of tunable exchange bias in SrYbRuO
The double perovskite compound, SrYbRuO, displays reversal in the
orientation of magnetic moments along with negative magnetization due to an
underlying magnetic compensation phenomenon. The exchange bias (EB) field below
the compensation temperature could be the usual negative or the positive
depending on the initial cooling field. This EB attribute has the potential of
getting tuned in a preselected manner, as the positive EB field is seen to
crossover from positive to negative value above .Comment: 4 Pages, 4 Figure
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