7,248 research outputs found
Gauge Invariance in Chern-Simons Systems
We show explicitly that the question of gauge invariance of the effective
potential in standard scalar electrodynamics remains unchanged despite the
introduction of the Chern-Simons term. The result does not depend on the
presence of the Maxwell term in the Chern-Simons territory.Comment: 10 pages, Plain Tex, DF/UFPB-14/9
The Peierls substitution in an engineered lattice potential
Artificial gauge fields open new possibilities to realize quantum many-body
systems with ultracold atoms, by engineering Hamiltonians usually associated
with electronic systems. In the presence of a periodic potential, artificial
gauge fields may bring ultracold atoms closer to the quantum Hall regime. Here,
we describe a one-dimensional lattice derived purely from effective
Zeeman-shifts resulting from a combination of Raman coupling and radiofrequency
magnetic fields. In this lattice, the tunneling matrix element is generally
complex. We control both the amplitude and the phase of this tunneling
parameter, experimentally realizing the Peierls substitution for ultracold
neutral atoms.Comment: 6 pages, 5 figure
Monolithic InP-Based Grating Spectrometer for Wavelength-Division Multiplexed Systems at 1.5 ÎŒm
A monolithic InP-based grating spectrometer for use in wavelength-division multiplexed systems at 1.5 ÎŒm is reported.
The spectrometer uses a single etched reflective focusing diffraction grating and resolves >50 channels at 1 nm spacing with a ~0.3nm channel width and at least 19dB channel isolation. Operation is essentially of the state of the input polarisation
Gauge Formulation of the Spinning Black Hole in (2+1)-Dimensional Anti-de Sitter Space
We compute the group element of SO(2,2) associated with the spinning black
hole found by Ba\~nados, Teitelboim and Zanelli in (2+1)-dimensional anti-de
Sitter space-time. We show that their metric is built with SO(2,2) gauge
invariant quantities and satisfies Einstein's equations with negative
cosmological constant everywhere except at . Moreover, although the metric
is singular on the horizons, the group element is continuous and possesses a
kink there.Comment: 10 page
Wavelength-selectable laser emission from a multistripe array grating integrated cavity laser
We report laser operation of a multistripe array grating integrated cavity (MAGIC) laser in which the wavelength of the emission from a single output stripe is chosen by selectively injection pumping a second stripe. We demonstrate a device that lases in the 1.5 ”m fiber band at 15 wavelengths, evenly spaced by ~2 nm. The single-output/wavelength-selectable operation, together with the accurate predefinition of the lasing wavelengths, makes the MAGIC laser a very attractive candidate for use in multiwavelength networks
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