79 research outputs found
Dynamical Casimir effect for magnons in a spinor Bose-Einstein condensate
Magnon excitation in a spinor Bose-Einstein condensate by a driven magnetic
field is shown to have a close analogy with the dynamical Casimir effect. A
time-dependent external magnetic field amplifies quantum fluctuations in the
magnetic ground state of the condensate, leading to magnetization of the
system. The magnetization occurs in a direction perpendicular to the magnetic
field breaking the rotation symmetry. This phenomenon is numerically
demonstrated and the excited quantum field is shown to be squeezed.Comment: 8 pages, 3 figure
Optical Aharonov-Bohm Effect on Wigner Molecules in Type-II Semiconductor Quantum Dots
We theoretically examine the magnetoluminescence from a trion and a biexciton
in a type-II semiconductor quantum dot, in which holes are confined inside the
quantum dot and electrons are in a ring-shaped region surrounding the quantum
dot. First, we show that two electrons in the trion and biexciton are strongly
correlated to each other, forming a Wigner molecule: Since the relative motion
of electrons is frozen, they behave as a composite particle whose mass and
charge are twice those of a single electron. As a result, the energy of the
trion and biexciton oscillates as a function of magnetic field with half the
period of the single-electron Aharonov-Bohm oscillation. Next, we evaluate the
photoluminescence. Both the peak position and peak height change
discontinuously at the transition of the many-body ground state, implying a
possible observation of the Wigner molecule by the optical experiment.Comment: 10 pages, 10 figures, accepted for publication in Phys. Rev.
Local gauge invariance implies Siegert's hypothesis
The nonrelativistic Ward-Takahashi identity, a consequence of local gauge
invariance in quantum mechanics, shows the necessity of exchange current
contributions in case of nonlocal and/or isospin-dependent potentials. It also
implies Siegert's hypothesis: in the nonrelativistic limit, two-body charge
densities identically vanish. Neither current conservation, which follows from
global gauge invariance, nor the constraints of (lowest order) relativity are
sufficient to arrive at this result. Furthermore, a low-energy theorem for
exchange contributions is established.Comment: 5 pages, REVTE
Dynamical Casimir effect without boundary conditions
The moving-mirror problem is microscopically formulated without invoking the
external boundary conditions. The moving mirrors are described by the quantized
matter field interacting with the photon field, forming dynamical cavity
polaritons: photons in the cavity are dressed by electrons in the moving
mirrors. The effective Hamiltonian for the polariton is derived, and
corrections to the results based on the external boundary conditions are
discussed.Comment: 12 pages, 2 figure
Space‐ and time‐resolved photoluminescence of In‐alloyed GaAs using photoluminescence excitation correlation spectroscopy
Ring Expansion of Cyclobutylmethylcarbenium Ions to Cyclopentane or Cyclopentene Derivatives and Metal-Promoted Analogous Rearrangements
Eppikajutsuto (a Japanese herbal medicine) regulates mTOR and induces apoptosis in oral cancer cells
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