13 research outputs found
Protecting Quantum Information with Entanglement and Noisy Optical Modes
We incorporate active and passive quantum error-correcting techniques to
protect a set of optical information modes of a continuous-variable quantum
information system. Our method uses ancilla modes, entangled modes, and gauge
modes (modes in a mixed state) to help correct errors on a set of information
modes. A linear-optical encoding circuit consisting of offline squeezers,
passive optical devices, feedforward control, conditional modulation, and
homodyne measurements performs the encoding. The result is that we extend the
entanglement-assisted operator stabilizer formalism for discrete variables to
continuous-variable quantum information processing.Comment: 7 pages, 1 figur
A quantization procedure based on completely positive maps and Markov operators
We describe -limit sets of completely positive (CP) maps over
finite-dimensional spaces. In such sets and in its corresponding convex hulls,
CP maps present isometric behavior and the states contained in it commute with
each other. Motivated by these facts, we describe a quantization procedure
based on CP maps which are induced by Markov (transfer) operators. Classical
dynamics are described by an action over essentially bounded functions. A
non-expansive linear map, which depends on a choice of a probability measure,
is the centerpiece connecting phenomena over function and matrix spaces
Wavelet representations and Fock space on positive matrices
We show that every biorthogonal wavelet determines a representation by
operators on Hilbert space satisfying simple identities, which captures the
established relationship between orthogonal wavelets and Cuntz-algebra
representations in that special case. Each of these representations is shown to
have tractable finite-dimensional co-invariant doubly-cyclic subspaces.
Further, motivated by these representations, we introduce a general Fock-space
Hilbert space construction which yields creation operators containing the
Cuntz--Toeplitz isometries as a special case.Comment: 32 pages, LaTeX ("amsart" document class), one EPS graphic file used
for shading, accepted March 2002 for J. Funct. Ana
Wavelets and graph -algebras
Here we give an overview on the connection between wavelet theory and
representation theory for graph -algebras, including the higher-rank
graph -algebras of A. Kumjian and D. Pask. Many authors have studied
different aspects of this connection over the last 20 years, and we begin this
paper with a survey of the known results. We then discuss several new ways to
generalize these results and obtain wavelets associated to representations of
higher-rank graphs. In \cite{FGKP}, we introduced the "cubical wavelets"
associated to a higher-rank graph. Here, we generalize this construction to
build wavelets of arbitrary shapes. We also present a different but related
construction of wavelets associated to a higher-rank graph, which we anticipate
will have applications to traffic analysis on networks. Finally, we generalize
the spectral graph wavelets of \cite{hammond} to higher-rank graphs, giving a
third family of wavelets associated to higher-rank graphs
Search for a heavy bottom-like quark in pp collisions at âs =7 TeV
This is the Pre-Print version of the Article. The official published version of the paper can be accessed from the link below - Copyright @ 2011 Elsevier.A search for pair-produced bottom-like quarks in pp collisions at sqrt(s) = 7 TeV is conducted with the CMS experiment at the LHC. The decay b' to tW is considered in this search. The b' b'-bar to tW^- t-bar W^+ process can be identified by the distinctive signature of trileptons and same-sign dileptons. With a data sample corresponding to an integrated luminosity of 34 inverse picobarns, no excess above the standard model background predictions is observed and a b' quark with a mass between 255 and 361 GeV/c^2 is excluded at the 95% confidence level.This work is supported by the FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences
and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3
(France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR
(Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)
The forward physics facility at the high-luminosity LHC
High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential
Protected subspaces in quantum information
Contains fulltext :
84157.pdf (preprint version ) (Open Access