5,102 research outputs found
Quark-Gluon Jet Differences at LEP
A new method to identify the gluon jet in 3-jet ``{\bf Y}'' decays of
is presented. The method is based on differences in particle multiplicity
between quark jets and gluon jets, and is more effective than tagging by
leptonic decay. An experimental test of the method and its application to a
study of the ``string effect'' are proposed. Various jet-finding schemes for
3-jet events are compared.Comment: 11 pages, LaTeX, 4 PostScript figures availble from the author
([email protected]), MSUTH-92-0
Dipolar particles in a double-trap confinement: Response to tilting the dipolar orientation
We analyze the microscopic few-body properties of dipolar particles confined
in two parallel quasi-one-dimensional harmonic traps. In particular, we show
that an adiabatic rotation of the dipole orientation about the trap axes can
drive an initially non-localized few-fermion state into a localized state with
strong inter-trap pairing. For an instant, non-adiabatic rotation, however,
localization is inhibited and a highly excited state is reached. This state may
be interpreted as the few-body analog of a super-Tonks-Girardeau state, known
from one-dimensional systems with contact interactions
Finite-size effects in the dynamics of few bosons in a ring potential
We study the temporal evolution of a small number of ultra-cold bosonic
atoms confined in a ring potential. Assuming that initially the system is in a
solitary-wave solution of the corresponding mean-field problem, we identify
significant differences in the time evolution of the density distribution of
the atoms when it instead is evaluated with the many-body Schr\"odinger
equation. Three characteristic timescales are derived: the first is the period
of rotation of the wave around the ring, the second is associated with a
"decay" of the density variation, and the third is associated with periodic
"collapses" and "revivals" of the density variations, with a factor of separating each of them. The last two timescales tend to infinity in the
appropriate limit of large , in agreement with the mean-field approximation.
These findings are based on the assumption of the initial state being a
mean-field state. We confirm this behavior by comparison to the exact solutions
for a few-body system stirred by an external potential. We find that the exact
solutions of the driven system exhibit similar dynamical features.Comment: To appear in Journal of Physics
A trick for passing degenerate points in Ashtekar formulation
We examine one of the advantages of Ashtekar's formulation of general
relativity: a tractability of degenerate points from the point of view of
following the dynamics of classical spacetime. Assuming that all dynamical
variables are finite, we conclude that an essential trick for such a continuous
evolution is in complexifying variables. In order to restrict the complex
region locally, we propose some `reality recovering' conditions on spacetime.
Using a degenerate solution derived by pull-back technique, and integrating the
dynamical equations numerically, we show that this idea works in an actual
dynamical problem. We also discuss some features of these applications.Comment: 9 pages by RevTeX or 16 pages by LaTeX, 3 eps figures and epsf-style
file are include
Candidate MKiD nucleus 106Rh in triaxial relativistic mean-field approach with time-odd fields
The configuration-fixed constrained triaxial relativistic mean-field approach
is extended by including time-odd fields and applied to study the candidate
multiple chiral doublets (MKiD) nucleus 106Rh. The energy contribution from
time-odd fields and microscopical evaluation of center-of-mass correction as
well as the modification of triaxial deformation parameters beta, gamma due to
the time-odd fields are investigated. The contributions of the time-odd fields
to the total energy are 0.1-0.3 MeV and they modify slightly the gamma values.
However, the previously predicted multiple chiral doublets still exist.Comment: 9 pages, 3 figures, accepted for publication as a Brief Report in
Physical Review
Understanding contextualised rational action - author's response
Understanding contextualised rational action - author's respons
Introduction to special issue. Distancing, disease and distress: The young and COVID-19: exploring young peopleâs experience of inequalities and their resourcefulness during the pandemic
The COVID-19 global pandemic has impacted everyoneâs livesâyoung and old. When the World Health Organization declared the COVID-19 outbreak a pandemic on 11 March 2020 and one country after another went into lockdown, we as editors of YOUNG and youth researchers living in five different countries naturally started to think about and reflect on what impact the pandemic would have on young peopleâs everyday lives, their well-being and futures across different national settings. In response to this uncertainty and in the interest of capturing young peopleâs experiences, we as editors called for this special issue to focus on young people and COVID-19, exploring their changed everyday lives and how they adapted to the global pandemic. To accommodate the immense interest and the high quality of many of the submissions, this special issue of YOUNG is a double issue with 11 articles
High fidelity readout scheme for rare-earth solid state quantum computing
We propose and analyze a high fidelity readout scheme for a single instance
approach to quantum computing in rare-earth-ion-doped crystals. The scheme is
based on using different species of qubit and readout ions, and it is shown
that by allowing the closest qubit ion to act as a readout buffer, the readout
error can be reduced by more than an order of magnitude. The scheme is shown to
be robust against certain experimental variations, such as varying detection
efficiencies, and we use the scheme to predict the expected quantum fidelity of
a CNOT gate in these solid state systems. In addition, we discuss the potential
scalability of the protocol to larger qubit systems. The results are based on
parameters which we believed are experimentally feasible with current
technology, and which can be simultaneously realized.Comment: 7 pages, 5 figure
Direct measurement of general quantum states using weak measurement
Recent work [J.S. Lundeen et al. Nature, 474, 188 (2011)] directly measured
the wavefunction by weakly measuring a variable followed by a normal (i.e.
`strong') measurement of the complementary variable. We generalize this method
to mixed states by considering the weak measurement of various products of
these observables, thereby providing the density matrix an operational
definition in terms of a procedure for its direct measurement. The method only
requires measurements in two bases and can be performed `in situ', determining
the quantum state without destroying it.Comment: This is a later and very different version of arXiv:1110.0727v3
[quant-ph]. New content: a method to directly measure each element of the
density matrix, specific Hamiltonians to weakly measure the product of
non-commuting observables, and references to recent related wor
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