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Double-quantum-well field-effect transistors with a grating gate exhibit a sharply resonant, voltage tuned terahertz photoconductivity. The voltage tuned resonance is determined by the plasma oscillations of the composite structure. The resonant photoconductivity requires a double-quantum well but the mechanism whereby plasma oscillations produce changes in(More)
Echolocating bats perceive objects as acoustic images derived from echoes of the ultrasonic sounds they emit. They can detect, track, identify, and intercept flying insects using sonar. Many species, such as the big brown bat, Eptesicus fuscus, emit frequency-modulated sonar sounds and perceive the distance to targets, or target range, from the delay of(More)
| Solid‐state lighting is a rapidly evolving technology, now virtually certain to someday displace traditional lighting in applications ranging from the lowest‐ power spot illuminator to the highest‐power area illuminator. Moreover, it has considerable headroom for continued evolution even after this initial displacement. In this article, we present a(More)
We report resistivity measurements from 0.03 to 10 K in a dilute high mobility 2D electron system. Using an undoped GaAs/AlGaAs heterojunction in a gated field-effect transistor geometry, a wide range of densities, 0.16 x 10(10) to 7.5 x 10(10) cm(-2), are explored. For high densities, the results are quantitatively shown to be due to scattering by acoustic(More)
Negative differential conductance has been observed in grid-shaped surface superlattices, realized in a high mobility two-dimensional electron system. The current-voltage characteristics vary with the modulation strength, indicating that the two-dimensional electronic transport properties can be manipulated in a controllable way. Theoretical modeling yields(More)
Nuclear magnetic resonance is detected via the in-plane conductivity of a two-dimensional electron system at unity Landau level filling factor in the regime of the quantum Hall effect in narrow and wide quantum wells. The NMR is spatially selective to nuclei with a coupling to electrons in the current carrying edge states at the perimeter of the 2DES.(More)
An experimental investigation is carried out into the attachment of a single particle to a liquid drop. High-speed videography is used to directly visualize the so-called 'snap-in' effect which occurs rapidly over sub-millisecond timescales. Using high-magnification, the evolution of the contact line around the particle is tracked and dynamic features such(More)