7,431 research outputs found
Unified Formalism for calculating Polarization, Magnetization, and more in a Periodic Insulator
In this paper, we propose a unified formalism, using Green's functions, to
integrate out the electrons in an insulator under uniform electromagnetic
fields. We derive a perturbative formula for the Green's function in the
presence of uniform magnetic or electric fields. Applying the formula, we
derive the formula for the polarization, the orbital magnetization, and the
orbital magneto-polarizability, without assuming time reversal symmetry.
Specifically, we realize that the terms linear in the electric field can only
be expressed in terms of the Green's functions in one extra dimension. This
observation directly leads to the result that the coefficient of the
term in any dimensions is given by a Wess-Zumino-Witten-type term, integrated
in the extended space, interpolating between the original physical Brillouin
zone and a trivial system, with the group element replaced by the Green's
function. This generalizes an earlier result for the case of time reversal
invariance [see Z. Wang, X.-L. Qi, and S.-C. Zhang, Phys. Rev. Lett. {\bf 105},
256803 (2010)].Comment: 16 pages, 1 figure. The version accepted by PR
Peak shifts due to rescattering in dipion transitions
We study the energy distributions of dipion transitions to
in the final state rescattering model. Since the
is well above the open bottom thresholds, the dipion transitions
are expected to mainly proceed through the real processes and . We find that the energy distributions of
markedly differ from that of . In particular, the resonance peak will be pushed up by
about 7-20 MeV for these dipion transitions relative to the main hadronic decay
modes. These predictions can be used to test the final state rescattering
mechanism in hadronic transitions for heavy quarkonia above the open flavor
thresholds.Comment: Version published in PRD, energy dependence of the total width in
Eq.(12) restored and corresponding figure changed, more discussion and
clarification adde
Non-separated states from squeezed dark-state polaritons in electromagnetically-induced-transparency media
Within the frame of quantized dark-state polaritons in
electromagnetically-induced-transparency media, noise fluctuations in the
quadrature components are studied. Squeezed state transfer, quantum
correlation, and noise entanglement between probe field and atomic polarization
are demonstrated in single- and double- configurations, respectively.
Even though a larger degree of squeezing parameter in the continuous variable
helps to establish stronger quantum correlations, inseparability criterion is
satisfied only within a finite range of squeezing parameter. The results
obtained in the present study may be useful for guiding experimental
realization of quantum memory devices for possible applications in quantum
information and computation.Comment: 12 pages, 7 figure
Squeezing and entanglement of matter-wave gap solitons
We study quantum squeezing and entanglement of gap solitons in a
Bose-Einstein condensate loaded into a one-dimensional optical lattice. By
employing a linearized quantum theory we find that quantum noise squeezing of
gap solitons, produced during their evolution, is enhanced compared with the
atomic solitons in a lattice-free case due to intra-soliton structure of
quantum correlations induced by the Bragg scattering in the periodic potential.
We also show that nonlinear interaction of gap solitons in dynamically stable
bound states can produce strong soliton entanglement.Comment: 4 pages, 5 figure
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