12,662 research outputs found
Tipping time of a quantum rod
The behaviour of a quantum rod, pivoted at its lower end on an impenetrable
floor and restricted to moving in the vertical plane under the gravitational
potential is studied analytically under the approximation that the rod is
initially localised to a small-enough neighbourhood around the point of
classical unstable equilibrium. It is shown that the rod evolves out of this
neighbourhood. The time required for this to happen, i.e., the tipping time is
calculated using the semi-classical path integral. It is shown that equilibrium
is recovered in the classical limit, and that our calculations are consistent
with the uncertainty principle.Comment: 10 pages, 1 figure, To appear in Euro. J. Phy
Characterization in bi-parameter space of a non-ideal oscillator
The authors thank scientific agencies CAPES, CNPq (112952/2015-1), and FAPESP (2011/ 19269-11). M. S. Baptista also thanks EPSRC (EP/I03 2606/1).Peer reviewedPostprin
Quantum Phase Diagram of the t-Jz Chain Model
We present the quantum phase diagram of the one-dimensional - model
for arbitrary spin (integer or half-integer) and sign of the spin-spin
interaction , using an {\it exact} mapping to a spinless fermion model
that can be solved {\it exactly} using the Bethe ansatz. We discuss its
superconducting phase as a function of hole doping . Motivated by the new
paradigm of high temperature superconductivity, the stripe phase, we also
consider the effect the antiferromagnetic background has on the - chain
intended to mimic the stripe segments.Comment: 4 pages, 2 figure
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