38,209 research outputs found
Entanglement between two fermionic atoms inside a cylindrical harmonic trap
We investigate quantum entanglement between two (spin-1/2) fermions inside a
cylindrical harmonic trap, making use of the von Neumann entropy for the
reduced single particle density matrix as the pure state entanglement measure.
We explore the dependence of pair entanglement on the geometry and strength of
the trap and on the strength of the pairing interaction over the complete range
of the effective BCS to BEC crossover. Our result elucidates an interesting
connection between our model system of two fermions and that of two interacting
bosons.Comment: to appear in PR
Calculation of compressible turbulent boundary layers with pressure gradients and heat transfer
Calculation of compressible turbulent boundary layers with pressure gradients and heat transfe
Dressed Qubits
Inherent gate errors can arise in quantum computation when the actual system
Hamiltonian or Hilbert space deviates from the desired one. Two important
examples we address are spin-coupled quantum dots in the presence of spin-orbit
perturbations to the Heisenberg exchange interaction, and off-resonant
transitions of a qubit embedded in a multilevel Hilbert space. We propose a
``dressed qubit'' transformation for dealing with such inherent errors. Unlike
quantum error correction, the dressed qubits method does not require additional
operations or encoding redundancy, is insenstitive to error magnitude, and
imposes no new experimental constraints.Comment: Replaced with published versio
The Fundamental-Weak Scale Hierarchy in the Standard Model
The multiple point principle, according to which several vacuum states with
the same energy density exist, is put forward as a fine-tuning mechanism
predicting the ratio between the fundamental and electroweak scales in the
Standard Model (SM). It is shown that this ratio is exponentially huge: . Using renormalisation group equations for the SM, we obtain the
effective potential in the 2-loop approximation and investigate the existence
of its postulated second minimum at the fundamental scale. The investigation of
the evolution of the top quark Yukawa coupling constant in the 2-loop
approximation shows that, with initial values of the top Yukawa coupling in the
interval (here is the top quark pole mass), a
second minimum of the SM effective potential can exist in the region
GeV. A prediction is made of the existence
of a new bound state of 6 top quarks and 6 anti-top quarks, formed due to Higgs
boson exchanges between pairs of quarks/anti-quarks. This bound state is
supposed to condense in a new phase of the SM vacuum. This gives rise to the
possibility of having a phase transition between vacua with and without such a
condensate. The existence of three vacuum states (new, electroweak and
fundamental) solves the hierarchy problem in the SM.Comment: 30 pages, 7 figures; to be published in Phys. Atom. Nuc
The Initial Value Problem For Maximally Non-Local Actions
We study the initial value problem for actions which contain non-trivial
functions of integrals of local functions of the dynamical variable. In
contrast to many other non-local actions, the classical solution set of these
systems is at most discretely enlarged, and may even be restricted, with
respect to that of a local theory. We show that the solutions are those of a
local theory whose (spacetime constant) parameters vary with the initial value
data according to algebraic equations. The various roots of these algebraic
equations can be plausibly interpreted in quantum mechanics as different
components of a multi-component wave function. It is also possible that the
consistency of these algebraic equations imposes constraints upon the initial
value data which appear miraculous from the context of a local theory.Comment: 8 pages, LaTeX 2 epsilo
F(750), We Miss You as a Bound State of 6 Top and 6 Antitop Quarks, Multiple Point Principle
We review our speculation, that in the pure Standard Model the exchange of
Higgses, including also the ones "eaten by and Z", and of gluons
together make a bound state of 6 top plus 6 anti top quarks bind so strongly
that its mass gets down to about 1/3 of the mass of the collective mass 12
of the 12 constituent quarks. The true importance of this speculated
bound state is that it makes it possible to uphold, even inside the Standard
Mode, our proposal for what is really a new law of nature saying that there are
several phases of empty space, vacua, all having very small energy densities
(of the order of the present energy density in the universe). The reason
suggested for believing in this new law called the "Multiple (Criticality)
Point Principle" is, that estimating the mass of the speculated bound state
using the "Multiple Point Principle" leads to two consistent mass-values; and
they even agree with a crude bag-model like estimate of the mass of this bound
state. Very, unfortunately, the statistical fluctuation so popular last year,
when interpreted as the digamma resonance F(750), turned out not to be a real
resonance, because our estimated bound state mass is just around the mass of
750 GeV.Comment: 25 pages, 11 figures, Corfu Summer Institute 2016 "School and
Workshops on Elementary Particle Physics and Gravity", 31 August - 23
September, 2016, Corfu, Greec
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