11,727 research outputs found
Dynamical quantum phase transition of a two-component Bose-Einstein condensate in an optical lattice
We study dynamics of a two-component Bose-Einstein condensate where the two
components are coupled via an optical lattice. In particular, we focus on the
dynamics as one drives the system through a critical point of a first order
phase transition characterized by a jump in the internal populations. Solving
the time-dependent Gross-Pitaevskii equation, we analyze; breakdown of
adiabaticity, impact of non-linear atom-atom scattering, and the role of a
harmonic trapping potential. Our findings demonstrate that the phase transition
is resilient to both contact interaction between atoms and external trapping
confinement.Comment: 8 pages, 8 figure
Quantum phase transitions in disordered dimerized quantum spin models and the Harris criterion
We use quantum Monte Carlo simulations to study effects of disorder on the
quantum phase transition occurring versus the ratio g=J/J' in square-lattice
dimerized S=1/2 Heisenberg antiferromagnets with intra- and inter-dimer
couplings J and J'. The dimers are either randomly distributed (as in the
classical dimer model), or come in parallel pairs with horizontal or vertical
orientation. In both cases the transition violates the Harris criterion,
according to which the correlation-length exponent should satisfy nu >= 1. We
do not detect any deviations from the three-dimensional O(3) universality class
obtaining in the absence of disorder (where nu = 0.71). We discuss special
circumstances which allow nu<1 for the type of disorder considered here.Comment: 4+ pages, 3 figure
Magnetic inversion symmetry breaking and ferroelectricity in TbMnO3
TbMnO3 is an orthorhombic insulator where incommensurate spin order for
temperature T_N < 41K is accompanied by ferroelectric order for T < 28K. To
understand this, we establish the magnetic structure above and below the
ferroelectric transition using neutron diffraction. In the paraelectric phase,
the spin structure is incommensurate and longitudinally-modulated. In the
ferroelectric phase, however, there is a transverse incommensurate spiral. We
show that the spiral breaks spatial inversion symmetry and can account for
magnetoelectricity in TbMnO3.Comment: 4 pages revtex, accepted by Phys. Rev. Lett. on June 21, 200
Informal Deference: A Historical, Empirical, and Normative Analysis of Patent Claim Construction
Informal Deference: A Historical, Empirical, and Normative Analysis of Patent Claim Construction
Robust entanglement generation by reservoir engineering
Following a recent proposal [C. Muschik et. al., Phys. Rev. A 83, 052312
(2011)], engineered dissipative processes have been used for the generation of
stable entanglement between two macroscopic atomic ensembles at room
temperature [H. Krauter et. al., Phys. Rev. Lett. 107, 080503 (2011)]. This
experiment included the preparation of entangled states which are continuously
available during a time interval of one hour. Here, we present additional
material, further-reaching data and an extension of the theory developed in [C.
Muschik et. al., Phys. Rev. A 83, 052312 (2011)]. In particular, we show how
the combination of the entangling dissipative mechanism with measurements can
give rise to a substantial improvement of the generated entanglement in the
presence of noise.Comment: Submitted to Journal of Physics B, special issue on "Quantum Memory
Restoring the Fact/Law Distinction in Patent Claim Construction
Two decades ago, the Supreme Court sought to promote more effective, transparent patent litigation in Markman v. Westview Instruments by ruling that “the construction of a patent, including terms of art within its claim, is exclusively within the province of the court.” In so doing, the Court removed interpretation of patent claims from the black box of jury deliberations by holding that the Seventh Amendment right to a jury trial did not extend to patent claim construction. Failing to find clear historical evidence of how claim construction was handled in 1791, the Court turned to “the relative interpretive skills of judges and juries and the statutory policies that ought to be furthered by the allocation.” It concluded that federal district court judges were better equipped than juries to resolve the mixed fact/law controversies inherent in construing disputed patent claim terms, thereby leading to more effective and transparent patent litigation. Fully achieving the Court’s goal of more effective and transparent patent litigation, however, depends on district judges having the flexibility to learn pertinent facts, build a reviewable record, and explain the basis for their claim constructions
Detecting Vanishing Dimensions Via Primordial Gravitational Wave Astronomy
Lower-dimensionality at higher energies has manifold theoretical advantages
as recently pointed out. Moreover, it appears that experimental evidence may
already exists for it - a statistically significant planar alignment of events
with energies higher than TeV has been observed in some earlier cosmic ray
experiments. We propose a robust and independent test for this new paradigm.
Since (2+1)-dimensional spacetimes have no gravitational degrees of freedom,
gravity waves cannot be produced in that epoch. This places a universal maximum
frequency at which primordial waves can propagate, marked by the transition
between dimensions. We show that this cut-off frequency may be accessible to
future gravitational wave detectors such as LISA.Comment: Somewhat expanded version with discussions that could not fit into
the PRL version; references adde
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