8,091 research outputs found
Crossover trimers connecting continuous and discrete scaling regimes
For a system of two identical fermions and one distinguishable particle
interacting via a short-range potential with a large s-wave scattering length,
the Efimov trimers and Kartavtsev-Malykh trimers exist in different regimes of
the mass ratio. The Efimov trimers are known to exhibit a discrete scaling
invariance, while the Kartavtsev-Malykh trimers feature a continuous scaling
invariance. We point out that a third type of trimers, "crossover trimers",
exist universally regardless of short-range details of the potential. These
crossover trimers have neither the discrete nor continuous scaling invariance.
We show that the crossover trimers continuously connect the discrete and
continuous scaling regimes as the mass ratio and the scattering length are
varied. We identify the regions for the Kartavtsev-Malykh trimers, Efimov
trimers, crossover trimers, and non-universal trimers as a function of the mass
ratio and the s-wave scattering length by investigating the scaling property
and model-independence of the trimers.Comment: 14 pages, 9 figure
Binary Patterns in Binary Cube-Free Words: Avoidability and Growth
The avoidability of binary patterns by binary cube-free words is investigated
and the exact bound between unavoidable and avoidable patterns is found. All
avoidable patterns are shown to be D0L-avoidable. For avoidable patterns, the
growth rates of the avoiding languages are studied. All such languages, except
for the overlap-free language, are proved to have exponential growth. The exact
growth rates of languages avoiding minimal avoidable patterns are approximated
through computer-assisted upper bounds. Finally, a new example of a
pattern-avoiding language of polynomial growth is given.Comment: 18 pages, 2 tables; submitted to RAIRO TIA (Special issue of Mons
Days 2012
Nurturing the young shoots of talent: Using action research for exploration and theory building
This is an Author's Accepted Manuscript of an article published in European Early Childhood Education Research Journal, 19(4), 433-450, 2011, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/1350293X.2011.623515.This paper reports the outcomes of a set of action research projects carried out by teacher researchers in 14 local education authorities in England, working collaboratively with university tutors, over a period of three years. The common aim of all the projects was to explore practical ways of nurturing the gifts and talents of children aged four–seven years. The project was funded by the Department of Education and Skills in England as part of the government's gifted and talented programme. The project teachers felt that their understanding of issues relating to nurturing the gifts and talents of younger children was enhanced through their engagement in the project. It was possible to map the findings of the projects to the English government's National Quality Standards for gifted and talented education which include: (1) identification; (2) effective provision in the classroom; (3) enabling curriculum entitlement and choice; (4) assessment for learning; (5) engaging with community, families and beyond. The findings are also analysed within the framework of good practice in educating children in the first years of schooling. Participating practitioners felt that action research offered them a suitable methodology to explore the complexity of the topic of giftedness through cycles of planning, action and reflection and personal theory building
Dispersive Response of a Disordered Superconducting Quantum Metamaterial
We consider a disordered quantum metamaterial formed by an array of
superconducting flux qubits coupled to microwave photons in a cavity. We map
the system on the Tavis-Cummings model accounting for the disorder in
frequencies of the qubits. The complex transmittance is calculated with the
parameters taken from state-of-the-art experiments. We demonstrate that photon
phase shift measurements allow to distinguish individual resonances in the
metamaterial with up to 100 qubits, in spite of the decoherence spectral width
being remarkably larger than the effective coupling constant. Our simulations
are in agreement with the results of the recently reported experiment.Comment: 10 pages, 4 figure
Non-universal Efimov Atom-Dimer Resonances in a Three-Component Mixture of 6Li
We observed an enhanced atom-dimer relaxation due to the existence of Efimov
states in a three-component mixture of 6Li atoms. We measured the
magnetic-field dependence of the atom-dimer loss coefficient in the mixture of
atoms in state |1> and dimers formed in states |2> and |3>, and found two peaks
corresponding to the degeneracy points of the |23> dimer energy level and
energy levels of Efimov trimers. We found that the locations of these peaks
disagree with universal theory predictions, in a way that cannot be explained
by non-universal two-body properties. We constructed theoretical models that
characterize the non-universal three-body physics of three-component 6Li atoms
in the low energy domain.Comment: 5 pages, 3 figure
Control of Andreev bound state population and related charge-imbalance effect
Motivated by recent experimental research, we study the processes in an ac
driven superconducting constriction whereby one quasiparticle is promoted to
the delocalized states outside the superconducting gap. We demonstrate that
with these processes one can control the population of the Andreev bound states
in the constriction. We stress an interesting charge asymmetry of these
processes that may produce a charge imbalance of accumulated quasiparticles,
which depends on the phase
A possible Efimov trimer state in a 3-component lithium-6 mixture
We consider the Efimov trimer theory as a possible framework to explain
recently observed losses by inelastic three-body collisions in a
three-hyperfine-component ultracold mixture of lithium 6. Within this
framework, these losses would arise chiefly from the existence of an Efimov
trimer bound state below the continuum of free triplets of atoms, and the loss
maxima (at certain values of an applied magnetic field) would correspond to
zero-energy resonances where the trimer dissociates into three free atoms. Our
results show that such a trimer state is indeed possible given the two-body
scattering lengths in the three-component lithium mixture, and gives rise to
two zero-energy resonances. The locations of these resonances appear to be
consistent with observed losses.Comment: 4 pages, 2 figures. Updated figures, equations and references as in
the published version. Note that there is a 1/2 factor missing in Eq. (6) of
the published versio
Frequency Division Multiplexing Readout and Simultaneous Manipulation of an Array of Flux Qubits
An important desired ingredient of superconducting quantum circuits is a
readout scheme whose complexity does not increase with the number of qubits
involved in the measurement. Here, we present a readout scheme employing a
single microwave line, which enables simultaneous readout of multiple qubits.
Consequently, scaling up superconducting qubit circuits is no longer limited by
the readout apparatus. Parallel readout of 6 flux qubits using a frequency
division multiplexing technique is demonstrated, as well as simultaneous
manipulation and time resolved measurement of 3 qubits. We discuss how this
technique can be scaled up to read out hundreds of qubits on a chip.Comment: 4 pages, 4 figure
Cross-correlations of coherent multiple Andreev reflections
We use the Landauer-B\"uttiker scattering theory for electronic transport to
calculate the current cross-correlations in a voltage-biased three-terminal
junction with all superconducting leads. At low bias voltage, when charge
transport is due to coherent multiple Andreev reflections, we find large
cross-correlations compared with their normal-state value. Furthermore,
depending on the parameters that characterize the properties of the scattering
region between the leads, the cross-correlations can reverse their sign with
respect to the case of non-interacting fermionic systems.Comment: 10 pages, 5 figures, Contribution for the special issue of Physica E
in memory of Markus B\"uttike
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