178 research outputs found
Rummukainen-Gottlieb's formula on two-particle system with different mass
L\"uscher established a non-perturbative formula to extract the elastic
scattering phases from two-particle energy spectrum in a torus using lattice
simulations. Rummukainen and Gottlieb further extend it to the moving frame,
which is devoted to the system of two identical particles. In this work, we
generalize Rummukainen-Gottlieb's formula to the generic two-particle system
where two particles are explicitly distinguishable, namely, the masses of the
two particles are different. The finite size formula are achieved for both
and symmetries. Our analytical results will be very helpful
for the study of some resonances, such as kappa, vector kaon, and so on.Comment: matching its published paper and make it concise, and to remove text
overlap with arXiv:hep-lat/9503028, arXiv:hep-lat/0404001 by other author
Excited electron-bubble states in superfluid helium-4: a time-dependent density functional approach
We present a systematic study on the excited electron-bubble states in
superfluid helium-4 using a time-dependent density functional approach. For the
evolution of the 1P bubble state, two different functionals accompanied with
two different time-development schemes are used, namely an accurate
finite-range functional for helium with an adiabatic approximation for electron
versus an efficient zero-range functional for helium with a real-time evolution
for electron. We make a detailed comparison between the quantitative results
obtained from the two methods, which allows us to employ with confidence the
optimal method for suitable problems. Based on this knowledge, we use the
finite-range functional to calculate the time-resolved absorption spectrum of
the 1P bubble, which in principle can be experimentally determined, and we use
the zero-range functional to real-time evolve the 2P bubble for several
hundreds of picoseconds, which is theoretically interesting due to the break
down of adiabaticity for this state. Our results discard the physical
realization of relaxed, metastable 2P electron-bubblesComment: 16 pages, 12 figure
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Production Cross-Sections for p+-and p--Mesons By 340 Mev Protons on Carbon and Lead At 90° to The Beam
Entanglement-induced electron coherence in a mesoscopic ring with two magnetic impurities
We investigate the Aharonov-Bohm (AB) interference pattern in the electron
transmission through a mesoscopic ring in which two identical non-interacting
magnetic impurities are embedded. Adopting a quantum waveguide theory, we
derive the exact transmission probability amplitudes and study the influence of
maximally entangled states of the impurity spins on the electron transmittivity
interference pattern. For suitable electron wave vectors, we show that the
amplitude of AB oscillations in the absence of impurities is in fact not
reduced within a wide range of the electron-impurity coupling constant when the
maximally entangled singlet state is prepared. Such state is thus able to
inhibit the usual electron decoherence due to scattering by magnetic
impurities. We also show how this maximally entangled state of the impurity
spins can be generated via electron scattering.Comment: 8 page
Non-Local Quantum Gates: a Cavity-Quantum-Electro-Dynamics implementation
The problems related to the management of large quantum registers could be
handled in the context of distributed quantum computation: unitary non-local
transformations among spatially separated local processors are realized
performing local unitary transformations and exchanging classical
communication. In this paper, we propose a scheme for the implementation of
universal non-local quantum gates such as a controlled-\gate{NOT} (\cnot)
and a controlled-quantum phase gate (\gate{CQPG}). The system we have chosen
for their physical implementation is a Cavity-Quantum-Electro-Dynamics (CQED)
system formed by two spatially separated microwave cavities and two trapped
Rydberg atoms. We describe the procedures to follow for the realization of each
step necessary to perform a specific non-local operation.Comment: 12 pages, 5 figures, RevTeX; extensively revised versio
Long-range forces between two excited mercury atoms and associative ionization
The long-range quadrupole-quadrupole () and leading dispersion
() interactions between all pairs of excited Hg() ,
, , and atoms are determined. The quadrupole moments are
calculated using the {\it ab initio} relativistic configuration-interaction
method coupled with many-body perturbation theory. The van der Waals
coefficients are approximated using previously calculated static
polarizabilities and expressions for the dispersion energy that are validated
with similar systems. The long-range interactions are critical for associative
ionization in thermal and cold collisions, and are found to be quite different
for different pairs of interacting states. Based on this knowledge and the
short-range parts of previously calculated potential curves, improved estimates
of the chemi-ionization cross sections are obtained.Comment: accepted in Phys Rev
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An approach for parameterizing mesoscale precipitating systems
A cumulus parameterization laboratory has been described which uses a reference numerical model to fabricate, calibrate and verify a cumulus parameterization scheme suitable for use in mesoscale models. Key features of this scheme include resolution independence and the ability to provide hydrometeor source functions to the host model. Thus far, only convective scale drafts have been parameterized, limiting the use of the scheme to those models which can resolve the mesoscale circulations. As it stands, the scheme could probably be incorporated into models having a grid resolution greater than 50 km with results comparable to the existing schemes for the large-scale models. We propose, however, to quantify the mesoscale circulations through the use of the cumulus parameterization laboratory. The inclusion of these mesoscale drafts in the existing scheme will hopefully allow the correct parameterization of the organized mesoscale precipitating systems
Upper Limit on the Magnetic Dipole Contribution to the 5p-8p Transition in Rb by Use of Ultracold Atom Spectroscopy
We report on hyperfine-resolved spectroscopic measurements of the
electric-dipole forbidden 5 transition in a sample of
ultracold Rb atoms. The hyperfine selection rules enable the weak
magnetic-dipole (M1) contribution to the transition strength to be
distinguished from the much stronger electric-quadrupole (E2) contribution. An
upper limit on the M1 transition strength is determined that is about 50 times
smaller than an earlier experimental determination. We also calculate the
expected value of the M1 matrix element and find that it is less than the upper
limit extracted from the experiment.Comment: 7 pages, 4 figures, 3 table
Optical angular momentum: Multipole transitions and photonics
The premise that multipolar decay should produce photons uniquely imprinted with a measurably corresponding angular momentum is shown in general to be untrue. To assume a one-to-one correlation between the transition multipoles involved in source decay and detector excitation is to impose a generally unsupportable one-to-one correlation between the multipolar form of emission transition and a multipolar character for the detected field. It is specifically proven impossible to determine without ambiguity, by use of any conventional detector, and for any photon emitted through the nondipolar decay of an atomic excited state, a unique multipolar character for the transition associated with its generation. Consistent with the angular quantum uncertainty principle, removal of a detector from the immediate vicinity of the source produces a decreasing angular uncertainty in photon propagation direction, reflected in an increasing range of integer values for the measured angular momentum. In such a context it follows that when the decay of an electronic excited state occurs by an electric quadrupolar transition, for example, any assumption that the radiation so produced is conveyed in the form of “quadrupole photons” is experimentally unverifiable. The results of the general proof based on irreducible tensor analysis invite experimental verification, and they signify certain limitations on quantum optical data transmission
Infrared electron modes in light deformed clusters
Infrared quadrupole modes (IRQM) of the valence electrons in light deformed
sodium clusters are studied by means of the time-dependent local-density
approximation (TDLDA). IRQM are classified by angular momentum components
20, 21 and 22 whose branches are separated by cluster
deformation. In light clusters with a low spectral density, IRQM are
unambiguously related to specific electron-hole excitations, thus giving access
to the single-electron spectrum near the Fermi surface (HOMO-LUMO region). Most
of IRQM are determined by cluster deformation and so can serve as a sensitive
probe of the deformation effects in the mean field. The IRQM branch 21 is coupled with the magnetic scissors mode, which gives a chance to detect
the latter. We discuss two-photon processes, Raman scattering (RS), stimulated
emission pumping (SEP), and stimulated adiabatic Raman passage (STIRAP), as the
relevant tools to observe IRQM. A new method to detect the IRQM population in
clusters is proposed.Comment: 22 pages, 6 figure
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