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QUROPE - aggregated feeds in category PhysicsenarXiv.org: Quantum Physics: Possibilities for Probabilities. (arXiv:1711.05740v1 [hep-th])
http://arxiv.org/abs/1711.05740
<p>In ordinary situations involving a small part of the universe, Born's rule
seems to work well for calculating probabilities of observations in quantum
theory. However, there are a number of reasons for believing that it is not
adequate for many cosmological purposes. Here a number of possible
generalizations of Born's rule are discussed, explaining why they are
consistent with the present statistical support for Born's rule in ordinary
situations but can help solve various cosmological problems.
</p>Fri, 17 Nov 2017 23:45:13 +0100arXiv.org: Quantum Physics: Approximations for the Lowest Energy Eigenstates in a Double Square Well Potential. (arXiv:1711.05745v1 [quant-ph])
http://arxiv.org/abs/1711.05745
<p>Highly accurate closed-form approximations are given for the ground state and
first excited state wavefunctions and energies for a nonrelativistic particle
in a one-dimensional double square well potential with a square barrier in
between (so that the potential is a sequence of five constant pieces that
alternate in value from being above and below the ground state and first
excited state energies), under the assumption that the barrier is sufficiently
wide that the tunneling across it is very small.
</p>Fri, 17 Nov 2017 23:45:13 +0100arXiv.org: Quantum Physics: Quantum Origami: Applying Transversal Gates and Measuring Topological Order. (arXiv:1711.05752v1 [quant-ph])
http://arxiv.org/abs/1711.05752
<p>In topology, a torus remains invariant under certain non-trivial
transformations known as modular transformations. In the context of
topologically ordered quantum states of matter, these transformations encode
the braiding statistics and fusion rules of emergent anyonic excitations and
thus serve as a diagnostic of topological order. Moreover, modular
transformations of higher genus surfaces, e.g.<p><a href="http://arxiv.org/abs/1711.05752">read more</a></p>
Fri, 17 Nov 2017 23:45:13 +0100arXiv.org: Quantum Physics: Thomas Precession for Dressed Particles. (arXiv:1711.05753v1 [hep-th])
http://arxiv.org/abs/1711.05753
<p>We consider a particle dressed with boundary gravitons in three-dimensional
Minkowski space. The existence of BMS transformations implies that the
particle's wavefunction picks up a Berry phase when subjected to changes of
reference frames that trace a closed path in the asymptotic symmetry group. We
evaluate this phase and show that, for BMS superrotations, it provides a
gravitational generalization of Thomas precession. In principle, such phases
are observable signatures of asymptotic symmetries.
</p>Fri, 17 Nov 2017 23:45:13 +0100arXiv.org: Quantum Physics: Solutions of the D-dimensional Schrodinger equation with the hyperbolic Poschl Teller potential plus modified ring shaped term. (arXiv:1711.05774v1 [quant-ph])
http://arxiv.org/abs/1711.05774
<p>In this paper, we solve the D-dimensional Schr\"odinger equation with
hyperbolic Poschl-Teller potential plus a generalized ring-shaped potential.
After the separation of variable in the hyperspherical coordinate. We used
Nikiforov-Uvarov (NU) method to solve the resulting radial equation and obtain
explicitly the energy level and the corresponding wave function in closed form.
The solutions to the angular part are solved using the NU approach as well.
</p>Fri, 17 Nov 2017 23:45:13 +0100arXiv.org: Quantum Physics: High-harmonic generation in solids with and without topological edge states. (arXiv:1711.05783v1 [physics.optics])
http://arxiv.org/abs/1711.05783
<p>High-harmonic generation (HHG) in the two topological phases of a finite,
one-dimensional, periodic structure is investigated using a self-consistent
time-dependent density functional theory (TDDFT) approach. For harmonic photon
energies smaller than the band gap, the harmonic yield is found to differ up to
fourteen orders of magnitude for the two topological phases. This giant
topological effect is explained by the degree of destructive interference in
the harmonic emission of all valence-band electrons, which strongly depends on
whether topological edge states are present or not.
</p>Fri, 17 Nov 2017 23:45:13 +0100arXiv.org: Quantum Physics: Scaling Trapped Ion Quantum Computers Using Fast Gates and Microtraps. (arXiv:1711.05875v1 [quant-ph])
http://arxiv.org/abs/1711.05875
<p>Most attempts to produce a scalable quantum information processing platform
based on ion traps have focused on the shuttling of ions in segmented traps. We
show that an architecture based on an array of microtraps with fast gates will
outperform architectures based on ion shuttling. This system requires higher
power lasers, but does not require the manipulation of potentials or shuttling
of ions. This improves optical access, reduces the complexity of the trap, and
reduces the number of conductive surfaces close to the ions. The use of fast
gates also removes limitations on gate time.<p><a href="http://arxiv.org/abs/1711.05875">read more</a></p>
Fri, 17 Nov 2017 23:45:13 +0100arXiv.org: Quantum Physics: Faster Methods for Contracting Infinite 2D Tensor Networks. (arXiv:1711.05881v1 [cond-mat.str-el])
http://arxiv.org/abs/1711.05881
<p>We revisit the Corner Transfer Matrix Renormalization Group (CTMRG) method of
Nishino and Okunishi for contracting 2-dimensional tensor networks, and
demonstrate that its performance can be substantially improved by determining
the tensors using an eigenvalue solver as opposed to the power method used in
CTMRG. We also generalize the variational uniform Matrix Product State (VUMPS)
ansatz for diagonalizing 1D quantum Hamiltonians to the case of 2D transfer
matrices, and discuss similarities with the corner methods.<p><a href="http://arxiv.org/abs/1711.05881">read more</a></p>
Fri, 17 Nov 2017 23:45:13 +0100arXiv.org: Quantum Physics: Quantum backflow of the relativistic spin-$1/2$ free particle. (arXiv:1711.05891v1 [quant-ph])
http://arxiv.org/abs/1711.05891
<p>It is shown that the free Dirac particle in a superposition of positive
momenta can in certain cases bear a negative probability current --- i.e., the
so-called quantum backflow --- as is in analogy with that in the
nonrelativistic limit. Further, more variations are brought about and
investigated when the negative-energy solutions are taken into account.<p><a href="http://arxiv.org/abs/1711.05891">read more</a></p>
Fri, 17 Nov 2017 23:45:13 +0100arXiv.org: Quantum Physics: What $g^{(2)}(0)<1/2$ tells you - and what it does not. (arXiv:1711.05897v1 [quant-ph])
http://arxiv.org/abs/1711.05897
<p>Quantum-optical research on semiconductor quantum dots puts special emphasis
on the measurement of the second-order correlation function $g^{(2)}(\tau)$,
arguing that $g^{(2)}(0)<1/2$ implies the source field represents a good
single-photon light source. We analyze this claim theoretically. A quantum
state of light having no projection on the single-photon Fock state can not
give a value of $g^{(2)}(0)<1/2$. However, with solely the value of
$g^{(2)}(0)$, the amplitude of this single-photon projection can be arbitrarily
small, owing to vacuum contributions.<p><a href="http://arxiv.org/abs/1711.05897">read more</a></p>
Fri, 17 Nov 2017 23:45:13 +0100