WTCP: A reliable transport protocol for wireless wide-area networks

  • Bharghavan V.
  • Nandagopal T.
  • Sinha P.
  • Sivakumar R.
  • Venkitaraman N.

Wireless wide-area networks (WWANs) are characterized by very low and variable bandwidths, very high and variable delays, significant non-congestion related losses, asymmetric uplink and downlink channels, and occasional blackouts. Additionally, the majority of the latency in a WWAN connection is incurred over the wireless link. Under such operating conditions, most ...

Synthesis and characterization of porous silica thin films deposited from MCM-41 evaporation

  • Barbeyto R.
  • Burgos L.
  • Garrido O.
  • Martinez-Duart J.
  • Poza M.
  • Ruiz-Hitzky E.
  • Shmytko I.
  • Velez M.

Silica thin films have been deposited on silicon substrates by electron beam evaporation using MCM-41 pressed powders as targets. Through X-ray diffraction, FT-IR (Fourier transform infrared) spectroscopy, SEM (scanning electron microscopy) and AFM (atomic force microscopy) techniques, the structure, composition and morphology of resulting films have been established. Transparent and ...

Observation of large many-body Coulomb interaction effects in a doped quantum wire

  • Akiyama H.
  • Pfeiffer L.
  • Pinczuk A.
  • West K.
  • Yoshita M.

We demonstrate strong one-dimensional (1D) many-body interaction effects in photoluminescence (PL) in a GaAs single quantum wire of unprecedented optical quality, where ID electron plasma densities are controlled via electrical gating. We observed PL of 1D charged excitons with large binding energy of 2.3 meV relative to the neutral excitons, ...

Evidence for 2k(F) electron-electron scattering processes in Coulomb drag

  • Eisenstein J.
  • Kellogg M.
  • Pfeiffer L.
  • West K.

Measurements and calculations, of Coulomb drag between two low density closely spaced. two-dimensional electron systems are reported. The experimentally measured drag exceeds that calculated in the random phase approximation by a significant, and density dependent, factor. Studies of the dependence of the measured drag on the difference in density between ...

The crossover between lasing and polariton condensation in optical microcavities

  • Littlewood P.
  • Szymanska M.

We study a model of a photon mode dipole-coupled to a medium of two-level oscillators in a microcavity in the presence of dephasing processes introduced by coupling to external baths. Decoherence processes can be classified as pair-breaking or non-pair-breaking in analogy with magnetic or non-magnetic impurities in superconductors. In the ...

Evaluation of two novel lead-free surface finishes

  • Fan C.
  • Lee N.
  • Ludwig R.
  • Zhang Y.

Two new electrolytically plated lead-free surface finishes are evaluated for their wettability, bond strength, and voiding performance, and are compared with electrolytic nickel gold and an OSP. The results indicate that Ni-Sn achieve the highest wettability, one of the highest lap shear strengths, and the lowest levels of voiding. It ...

On some polynomials related to weight enumerators of linear codes

  • Barg A.

A linear code can be thought of as a vector matroid represented by the columns of the code's generator matrix; a well-known result in this context is Greene's theorem on a connection of the weight polynomial of the code and the Tutte polynomial of the matroid. W examine this connection ...

Safe zones for shock-protection of fragile components during impact-induced clatter

  • Goyal S.
  • Papadopoulos J.

Clattering motion that occurs when flat objects strike the ground at an oblique angle is studied through a simple, tractable, model of a rigid bar with arbitrary, but symmetric, mass distribution and coefficient of restitution. The maximum velocity changes, or velocity shocks, that occur at various locations of the bar ...

An all-cryogenic THz transmission spectrometer

  • Burke P.
  • Eisenstein J.
  • Pfeiffer L.
  • West K.

This article describes a THz transmission spectrometer for the spectral range of 2-65 cm(-1) (100 GHz to 2 THz) with a spectral resolution of at least 1.8 cm(-1) (50 GHz) where the source, sample, and detector are all fully contained in a cryogenic environment. Cyclotron emission from a two-dimensional electron ...

On the classical character of control fields in quantum information processing

  • Kimble H.
  • Van Enk S.

Control fields in quantum information processing are almost by definition assumed to be classical. In reality, however, when such a field is used to manipulate the quantum state of qubits, the qubits always become slightly entangled with the field. For quantum information processing this is an undesirable property, as it ...

Lead-free component finishes - A market & technical analysis

  • Swanson J.
  • Zhang Y.

In this edited version of a paper given at SUR/FIN(R) 2001-Nashville, a marketing perspective of the change and transition to leadfree alternatives for component finishes is presented. What drives the change? Legislation, the corporate ``environmental conscience,{''} market needs, or a combination of these factors? The authors report on the status ...

The fate of quantum Hall extended states as B -> 0 and the possibility of a 2D metal

  • Clark R.
  • Hamilton A.
  • Lumpkin N.
  • Pfeiffer L.
  • Simmons M.
  • West K.
  • Yasin C.

We report the study of two-dimensional `metallic' behaviour at B = 0 in ultra-high-quality n-GaAs (mu(peak) > 10(7) cm(2) V-1 s(-1)). and in particular address the question of what happens to the quantum Hall extended states at the centre of Landau levels as B --> 0. In these high-quality electron ...

Metal-insulator transition of spatially separated electrons and holes in mixed type I-type II GaAs/AlAs quantum wells

  • Ashkinadze B.
  • Mccombe B.
  • Pfeiffer L.
  • Yeo T.

Low temperature photo-induced far-infrared and microwave absorption studies of mixed type I-type II GaAs/AlAs multiple quantum wells have revealed features related to a metal-insulator transition. The far infrared experiments show an absorption feature at fields below electron cyclotron resonance (eCR) that shifts up with increasing electron-hole density and eventually pins ...

Optical investigation of high-mobility dilute two-dimensional hole gases in GaAs (3 1 1)A quantum structures

  • Dennis B.
  • Hirjibehedin C.
  • Pfeiffer L.
  • Pinczuk A.
  • Plaut A.
  • West K.

We have investigated the photoluminescence (PL) and inelastic light-scattering spectra of dilute two-dimensional (2D) hole gases of ultra-high mobility. The samples were GaAs-AlxGa1-xAs (311)A quantum structures, modulation-doped with Si. We find these samples not to deplete fully on illumination. The PL displays both excitonic and 2D hole gas transitions. We ...

Magnetic field effect on the free electron-exciton scattering in GaAs/AlGaAs bare quantum wells and in microcavities

  • Cohen E.
  • Maan A.
  • Pfeiffer L.
  • Qarry A.
  • Ramon G.
  • Rapaport R.
  • Ron A.

We report on a detailed study of the free electron scattering effects on the (e1: hh1)1S and (e1: 1h1)1S excitons in a GaAs quantum well with a variable density two-dimensional electron gas, that is either bare or embedded in a GaAs/AlGaAs microcavity. These effects are studied by measuring the reflection ...

The lever-arm model: describing resonant tunneling under bias at a fractional quantum Hall edge

  • Chang A.
  • Grayson M.
  • Pfeiffer L.
  • Tsui D.
  • West K.

New tunnel current measurements of resonant tunneling at a voltage-biased quantum Hall effect edge are reported and explained with an in-depth discussion of the lever-arm model proposed previously by the authors. The results support the power-law description of the density of states at a sharp fractional quantum Hall edge. (C) ...

Relaxation of silica above and below T-g: light scattering studies

  • Champagnon B.
  • Guenot P.
  • Le Parc R.

In a pure silica glass, different fictive temperatures are achieved between 1500 and 1100degreesC. These temperatures are checked by the position of the Si-O-Si Raman band. Light scattering for the different samples due to density fluctuations is determined by the Landau-Placzek ratio which decreases when T-f decreases. Further relaxation occurs ...

64-QAM hybrid DWDM/SCM bidirectional interleaved fiber transmission systems

  • Bethea C.
  • Delavaux J.
  • Hullin C.
  • Neyret B.
  • Radic S.
  • Wilson G.

We report bidirectional interleaved 8 wavelength DWDM/SCM transmission over 212 and 238 km of standard single-mode fiber in repeaterless and repeated system configurations. We demonstrate error-free transmission using electroabsorption modulated laser transmitters with 1.04 Gbps payload each in 35 6-MHz 64-QAM channels. (C) 2002 Elsevier Science (USA).

Investigation of cross-phase modulation-induced transmission penalties using the pump-probe technique

  • Bayvel P.
  • Killey R.
  • Thiele H.

The cross-phase modulation effect and the resulting induced distortion in single-mode optical fiber are investigated in multichannel systems. A simple technique is described to estimate the impact of cross-phase modulation on WDM transmission penalties. The induced distortion build-up is characterized as a function of channel spacing and distance in pump-probe ...

Evanescent-wave gas sensing using microstructure fiber

  • Ho H.
  • Hoo Y.
  • Jin W.
  • Wang D.
  • Windeler R.

We report the experimental demonstration of evanescent-wave gas detection with a silica-air microstructure fiber. Detection sensitivity of similar to6% of that of direction absorption spectroscopy per equal length has been achieved. (C) 2002 Society of Photo-Optical Instrumentation Engineers.