1,452 research outputs found
Renormalized masses of heavy Kaluza-Klein states
Several ways of computing the radiative corrections to the heavy boson masses
in Kaluza-Klein theory are discussed. It is argued that only an intrinsically
higher dimensional approach embodies all the desired physical properties.Comment: LaTeX, 22 pages. Fully rewritten and streamlined. Five and six
dimensional cases treated separatelly. References adde
Operation speed of polariton condensate switches gated by excitons
We present a time-resolved photoluminescence (PL) study in real- and
momentum-space of a polariton condensate switch in a quasi-1D semiconductor
microcavity. The polariton flow across the ridge is gated by excitons inducing
a barrier potential due to repulsive interactions. A study of the device
operation dependence on the power of the pulsed gate beam obtains a
satisfactory compromise for the ON/OFF-signal ratio and -switching time of the
order of 0.3 and ps, respectively. The opposite transition is
governed by the long-lived gate excitons, consequently the OFF/ON-switching
time is ps, limiting the overall operation speed of the device
to GHz. The experimental results are compared to numerical
simulations based on a generalized Gross-Pitaevskii equation, taking into
account incoherent pumping, decay and energy relaxation within the condensate.Comment: 11 pages, 11 figure
Energy relaxation of exciton-polariton condensates in quasi-1D microcavities
We present a time-resolved study of energy relaxation and trapping dynamics
of polariton condensates in a semiconductor microcavity ridge. The combination
of two non-resonant, pulsed laser sources in a GaAs ridge-shaped microcavity
gives rise to profuse quantum phenomena where the repulsive potentials created
by the lasers allow the modulation and control of the polariton flow. We
analyze in detail the dependence of the dynamics on the power of both lasers
and determine the optimum conditions for realizing an all-optical polariton
condensate transistor switch. The experimental results are interpreted in the
light of simulations based on a generalized Gross-Pitaevskii equation,
including incoherent pumping, decay and energy relaxation within the
condensate.Comment: 15 pages, 20 figure
Dynamics of a polariton condensate transistor switch
We present a time-resolved study of the logical operation of a polariton
condensate transistor switch. Creating a polariton condensate (source) in a
GaAs ridge-shaped microcavity with a non-resonant pulsed laser beam, the
polariton propagation towards a collector, at the ridge edge, is controlled by
a second weak pulse (gate), located between the source and the collector. The
experimental results are interpreted in the light of simulations based on the
generalized Gross-Pitaevskii equation, including incoherent pumping, decay and
energy relaxation within the condensate.Comment: 4 pages, 2 figure
Experimental and predicted vapour-liquid equilibrium of the binary mixtures n-heptane + chlorobutane isomers
The study of the isothermal vapour-liquid equilibrium (VLE) of the binary mixtures n-heptane plus chlorobutane isomers (1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane or 2-chloro-2-methylpropane) at three different temperatures, T = 288.15, 298.15 and 308.15 K, is presented in this contribution. The experimental results were correlated using Wilson equation and the thermodynamic consistency of the data was checked by the van Ness method. Furthermore, two different methods have been used to predict the phase equilibrium in isothermal conditions: a pure group contribution method (modified-UNIFAC) and a group contribution equation of state (VTPR)
Spin Selective Filtering of Polariton Condensate Flow
Spin-selective spatial filtering of propagating polariton condensates, using
a controllable spin-dependent gating barrier, in a one-dimensional
semiconductor microcavity ridge waveguide is reported. A nonresonant laser beam
provides the source of propagating polaritons while a second circularly
polarized weak beam imprints a spin dependent potential barrier, which gates
the polariton flow and generates polariton spin currents. A complete spin-based
control over the blocked and transmitted polaritons is obtained by varying the
gate polarization.Comment: 5 pages, 4 figure
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