331 research outputs found
Supercurrent survival under Rosen-Zener quench of hard core bosons
We study the survival of super-currents in a system of impenetrable bosons
subject to a quantum quench from its critical superfluid phase to an insulating
phase. We show that the evolution of the current when the quench follows a
Rosen-Zener profile is exactly solvable. This allows us to analyze a quench of
arbitrary rate, from a sudden destruction of the superfluid to a slow opening
of a gap. The decay and oscillations of the current are analytically derived,
and studied numerically along with the momentum distribution after the quench.
In the case of small supercurrent boosts , we find that the current
surviving at long times is proportional to
The Perpetuation of Graffiti Art Subculture
Graffiti art and the subculture that supports it is a form of graffiti that differs from gang graffiti, immediate graffiti, and street art. This research is a qualitative analysis using partial participant observation of a graffiti art subculture in a Midwestern city. Six themes which characterize this subculture were individual identity, communication, competition, criminality, aesthetic criteria, and changing forms of communication. The implications of the findings for labeling theory and differential association theories are discussed
Dramatikus gyakorlatok az idegennyelv-tanĂtásban
A szerepjátĂ©k, dramatikus gyakorlat, drámajátĂ©k az idegen nyelv tanĂtásában is jĂłl ismert fogalmak Az alábbiakban csak a dramatikus gyakorlatot mutatjuk be
Physics of hollow Bose-Einstein condensates
Bose-Einstein condensate shells, while occurring in ultracold systems of
coexisting phases and potentially within neutron stars, have yet to be realized
in isolation on Earth due to the experimental challenge of overcoming
gravitational sag. Motivated by the expected realization of hollow condensates
by the space-based Cold Atomic Laboratory in microgravity conditions, we study
a spherical condensate undergoing a topological change from a filled sphere to
a hollow shell. We argue that the collective modes of the system show marked
and robust signatures of this hollowing transition accompanied by the
appearance of a new boundary. In particular, we demonstrate that the frequency
spectrum of the breathing modes shows a pronounced depression as it evolves
from the filled sphere limit to the hollowing transition. Furthermore, when the
center of the system becomes hollow surface modes show a global restructuring
of their spectrum due to the availability of a new, inner, surface for
supporting density distortions. We pinpoint universal features of this
topological transition as well as analyse the spectral evolution of collective
modes in the experimentally relevant case of a bubble-trap.Comment: 8 pages, 4 figure
Inelastic neutron scattering signal from deconfined spinons in a fractionalized antiferromagnet
We calculate the contribution of deconfined spinons to inelastic neutron
scattering (INS) in the fractionalized antiferromagnet (AF*), introduced
elsewhere. We find that the presence of free spin-1/2 charge-less excitations
leads to a continuum INS signal above the Neel gap. This signal is found above
and in addition to the usual spin-1 magnon signal, which to lowest order is the
same as in the more conventional confined antiferromagnet. We calculate the
relative weights of these two signals and find that the spinons contribute to
the longitudinal response, where the magnon signal is absent to lowest order.
Possible higher-order effects of interactions between magnons and spinons in
the AF* phase are also discussed.Comment: 9 page
Static and dynamic properties of shell-shaped condensates
Static, dynamic, and topological properties of hollow systems differ from
those that are fully filled as a result of the presence of a boundary
associated with an inner surface. Hollow Bose-Einstein condensates (BECs)
naturally occur in various ultracold atomic systems and possibly within neutron
stars but have hitherto not been experimentally realized in isolation on Earth
because of gravitational sag. Motivated by the expected first realization of
fully closed BEC shells in the microgravity conditions of the Cold Atomic
Laboratory aboard the International Space Station, we present a comprehensive
study of spherically symmetric hollow BECs as well as the hollowing transition
from a filled sphere BEC into a thin shell through central density depletion.
We employ complementary analytic and numerical techniques in order to study
equilibrium density profiles and the collective mode structures of condensate
shells hosted by a range of trapping potentials. We identify concrete and
robust signatures of the evolution from filled to hollow structures and the
effects of the emergence of an inner boundary, inclusive of a dip in
breathing-mode-type collective mode frequencies and a restructuring of surface
mode structure across the transition. By extending our analysis to a
two-dimensional transition of a disk to a ring, we show that the collective
mode signatures are an essential feature of hollowing, independent of the
specific geometry. Finally, we relate our work to past and ongoing experimental
efforts and consider the influence of gravity on thin condensate shells. We
identify the conditions under which gravitational sag is highly destructive and
study the mode-mixing effects of microgravity on the collective modes of these
shells.Comment: 26 pages, 13 figure
Miért nem érti egymást szülő és pedagógus?
Tanulmányunkban a szĂĽlĹ‘k Ă©s pedagĂłgusok közötti kommunikáciĂł gyakoriságárĂłl Ă©s minĹ‘sĂ©gĂ©rĹ‘l lesz szĂł. Ideális esetben a kĂ©t fĂ©l egymás partnere abban, hogy a gyermek minĂ©l boldogabb Ă©s sikeresebb felnĹ‘ttĂ© váljon. S bár a cĂ©lban egyetĂ©rtenek, az odavezetĹ‘ eszközökben már gyakran nincs egyetĂ©rtĂ©s. A szĂĽlĹ‘k Ă©s gyerekek beleszĂłlási jogai a rendszerváltás után egy idĹ‘re kiszĂ©lesedtek, jelenleg viszont a pedagĂłgus szakma csökkenĹ‘ presztĂzsĂ©t rĂ©szben az Ăşn. laikusok helyrerakásával igyekeznek növelni. De bárhogyan is szűkĂti vagy szĂ©lesĂti a szabályozás a szĂĽlĹ‘k jogait, igazán eredmĂ©nyes oktatás csak ott zajlik, ahol a pedagĂłgus Ă©s szĂĽlĹ‘ tandemben támogatja a tanulĂłk fejlĹ‘dĂ©sĂ©t. Ehhez pedig nĂ©lkĂĽlözhetetlen, hogy okos partneri viszonyt tudjanak egymással lĂ©tesĂteni. A tanulmány egy viszonylag friss online szĂĽlĹ‘i felmĂ©rĂ©s mellett bemutatja az ezen a tĂ©ren eddig szĂĽletett kutatási eredmĂ©nyeket Ă©s nemzetközi jĂł gyakorlatokat is
Inelastic Neutron Scattering Signal from Deconfined Spinons in a Fractionalized Antiferromagnet
We calculate the contribution of deconfined spinons to inelastic neutron scattering (INS) in the fractionalized antiferromagnet (AF*), introduced elsewhere. We find that the presence of free spin-1/2 charge-less excitations leads to a continuum INS signal above the NĂ©el gap. This signal is found above and in addition to the usual spin-1 magnon signal, which to lowest order is the same as in the more conventional confined antiferromagnet. We calculate the relative weights of these two signals and find that the spinons contribute to the longitudinal response, where the magnon signal is absent to lowest order. Possible higher-order effects of interactions between magnons and spinons in the AF* phase are also discussed
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