84,678 research outputs found
Measurement of surface potential decay of corona-charged polymer films using the pulsed electroacoustic method
In this paper, the pulsed electroacoustic (PEA) technique that allows the determination of space charge in a dielectric material has been used to monitor the electrical potential decay of corona-charged polyethylene films of different thicknesses. To prevent possible disturbance on the surface charge during the PEA measurements, two thin polyethylene films were placed on both sides of the corona-charged sample. Charge profiles measured at different times were used to calculate the potential across the sample. The obtained potential decay was compared with the potential measured using the conventional method. A good agreement has been obtained. More importantly, the charge profile obtained using the PEA technique indicates that bipolar charge injection has taken place
A binary mixture of spinor atomic Bose-Einstein condensates
We study the ground state and classify its phase diagram for a mixture of two
spin-1 condensates in the absence of external magnetic (B-) field according to
atomic parameters for intra- and inter-species spin exchange coupling and
singlet pairing interaction. Ignoring the inter-species singlet pairing
interaction, the ground state phases are found analytically. Numerical approach
of simulated annealing is adopted when the singlet pairing interaction is
present. Our results on the phase diagram and the boundaries between phases
allow for easy identifications of quantum phase transitions, that can be
induced through the tuning of optical traps and atom numbers. They provide the
first insight and guidance for several ongoing experiments on mixtures of
spinor condensates.Comment: 5 pages, 4 figure
Quantum entangled ground states of two spinor Bose-Einstein condensates
We revisit in detail the non-mean-field ground-state phase diagram for a
binary mixture of spin-1 Bose-Einstein condensates including quantum
fluctuations. The non-commuting terms in the spin-dependent Hamiltonian under
single spatial mode approximation make it difficult to obtain exact
eigenstates. Utilizing the spin z-component conservation and the total spin
angular momentum conservation, we numerically derive the information of the
building blocks and evaluate von Neumann entropy to quantify the ground states.
The mean-field phase boundaries are found to remain largely intact, yet the
ground states show fragmented and entangled behaviors within large parameter
spaces of interspecies spin-exchange and singlet-pairing interactions.Comment: 7 pages, 5 figure
Quantum spin mixing in a binary mixture of spin-1 atomic condensates
We study quantum spin mixing in a binary mixture of spin-1 condensates
including coherent interspecies mixing process, using the familiar spinor
condensates of Rb and Na atoms in the ground lower hyperfine F=1
manifolds as prototype examples. Within the single spatial mode approximation
for each of the two spinor condensates, the mixing dynamics reduce to that of
three coupled nonlinear pendulums with clear physical interpretations. Using
suitably prepared initial states, it is possible to determine the interspecies
singlet-pairing as well as spin-exchange interactions from the subsequent
mixing dynamics.Comment: 6 pages, 3 figure
- ā¦