202 research outputs found
Model Independent Framework for Searches of Top Partners
We propose a model-independent and general framework to study the LHC
phenomenology of top partners, i.e. Vector-Like quarks including particles with
different electro-magnetic charge. We consider Vector-Like quarks embedded in
general representations of the weak SU(2)L, coupling to all Standard Model
quarks via Yukawa mixing focusing on the case of a single multiplet. We show
that, with very minimal and quite general assumptions, top partners may be
studied in terms of few parameters in an effective Lagrangian description with
a clear and simple connection with experimental observables. We also
demonstrate that the parametrisation can be applied as well to cases with many
Vector-like multiplets, thus covering most realistic models of New Physics. We
perform a numerical study to understand the conclusions which can be drawn
within such a description and the expected potential for discovery or exclusion
at the LHC. Our main results are a clear connection between branching ratios
and single production channels, and the identification of novel interesting
channels to be studied at the LHC.Comment: 42 pages, 2 figures, 20 tables, added an appendix with a discussion
of coupling chirality in general scenarios; added a comparison of collider
and flavour bounds; added details about the range of validity of the
framework. References adde
Microoptical Realization of Arrays of Selectively Addressable Dipole Traps: A Scalable Configuration for Quantum Computation with Atomic Qubits
We experimentally demonstrate novel structures for the realisation of
registers of atomic qubits: We trap neutral atoms in one and two-dimensional
arrays of far-detuned dipole traps obtained by focusing a red-detuned laser
beam with a microfabricated array of microlenses. We are able to selectively
address individual trap sites due to their large lateral separation of 125 mu
m. We initialize and read out different internal states for the individual
sites. We also create two interleaved sets of trap arrays with adjustable
separation, as required for many proposed implementations of quantum gate
operations
Framework for Model Independent Analyses of Multiple Extra Quark Scenarios
In this paper we present an analysis strategy and a dedicated tool to
determine the exclusion confidence level for any scenario involving multiple
heavy extra quarks with generic decay channels, as predicted in several
extensions of the Standard Model. We have created, validated and used a
software package, called XQCAT (eXtra Quark Combined Analysis Tool), which is
based on publicly available experimental data from direct searches for top
partners and from Supersymmetry inspired searches. By means of this code, we
recast the limits from CMS on new heavy extra quarks considering a complete set
of decay channels. The resulting exclusion confidence levels are presented for
some simple scenarios with multiple states and general coupling assumptions.
Highlighting the importance of combining multiple topology searches to obtain
accurate re-interpretations of the existing searches, we discuss the reach of
the SUSY analyses so as to set bounds on new quark resonances. In particular,
we report on the re-interpretation of the existing limits on benchmark
scenarios with one and multiple pair-produced top partners having non-exclusive
couplings to the third Standard Model generation of quarks.Comment: 31 pages, 6 figures, 3 tables, version accepted for publication in
JHE
Atom Optics with Microfabricated Optical Elements
We introduce a new direction in the field of atom optics, atom interferometry, and neutral-atom quantum information processing. It is based on the use of microfabricated optical elements. With these elements versatile and integrated atom optical devices can be created in a compact fashion. This approach opens the possibility to scale, parallelize, and miniaturize atom optics for new investigations in fundamental research and application. It will lead to new, compact sources of ultracold atoms, compact sensors based on matter wave interference and new approaches towards quantum computing with neutral atoms. The exploitation of the unique features of the quantum mechanical behavior of matter waves and the capabilities of powerful state-of-the-art micro- and nanofabrication techniques lend this approach a special attraction
Coherent Patterning of Matter Waves with Subwavelength Localization
We propose the Subwavelength Localization via Adiabatic Passage (SLAP)
technique to coherently achieve state-selective patterning of matter waves well
beyond the diffraction limit. The SLAP technique consists in coupling two
partially overlapping and spatially structured laser fields to three internal
levels of the matter wave yielding state-selective localization at those
positions where the adiabatic passage process does not occur. We show that by
means of this technique matter wave localization down to the single nanometer
scale can be achieved. We analyze in detail the potential implementation of the
SLAP technique for nano-lithography with an atomic beam of metastable Ne* and
for coherent patterning of a two-component 87Rb Bose-Einstein condensate.Comment: 6 pages, 5 figure
Atomtronics with holes: Coherent transport of an empty site in a triple well potential
We investigate arrays of three traps with two fermionic or bosonic atoms. The
tunneling interaction between neighboring sites is used to prepare multi-site
dark states for the empty site, i.e., the hole, allowing for the coherent
manipulation of its external degrees of freedom. By means of an ab initio
integration of the Schr\"odinger equation, we investigate the adiabatic
transport of a hole between the two extreme traps of a triple-well potential.
Furthermore, a quantum-trajectory approach based on the de Broglie-Bohm
formulation of quantum mechanics is used to get physical insight into the
transport process. Finally, we discuss the use of the hole for the construction
of a coherent single hole diode and a coherent single hole transistor.Comment: 9 pages, 6 figure
Coherent manipulation of atomic qubits in optical micropotentials
We experimentally demonstrate the coherent manipulation of atomic states in
far-detuned dipole traps and registers of dipole traps based on two-dimensional
arrays of microlenses. By applying Rabi, Ramsey, and spin-echo techniques, we
systematically investigate the dephasing mechanisms and determine the coherence
time. Simultaneous Ramsey measurements in up to 16 dipole traps are performed
and proves the scalability of our approach. This represents an important step
in the application of scalable registers of atomic qubits for quantum
information processing. In addition, this system can serve as the basis for
novel atomic clocks making use of the parallel operation of a large number of
individual clocks each remaining separately addressable.Comment: to be published in Appl. Phys.
Multiple micro-optical atom traps with a spherically aberrated laser beam
We report on the loading of atoms contained in a magneto-optic trap into
multiple optical traps formed within the focused beam of a CO_{2} laser. We
show that under certain circumstances it is possible to create a linear array
of dipole traps with well separated maxima. This is achieved by focusing the
laser beam through lenses uncorrected for spherical aberration. We demonstrate
that the separation between the micro-traps can be varied, a property which may
be useful in experiments which require the creation of entanglement between
atoms in different micro-traps. We suggest other experiments where an array of
these traps could be useful.Comment: 10 pages, 3 figure
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