Article Abstract:
A small voltage can be used to change the properties of a newly-developed cascade laser. The gain of traditional lasers is determined by material properties, but the gain of the new device is determined by the transition probability created by the spatial overlap of the low-energy and excited states. The photon wavelength and energy difference can be tuned and the likelihood of decay can be altered, while different voltages can be applied to independently operate two or more parts of the unit at different wavelengths. Potential uses for the versatile laser include communications and spectroscopy.
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Article Abstract:
Two new experiments have succeeded in creating smaller loops of superconducting material than the superconducting quantum interference devices (SQUIDS). These loops are used to measure the slight quantum-mechanical interaction between current and magnetic fields through current oscillations that are created in response to the interaction. However, the difficulty in manufacturing these new, more sensitive circuits and their lower temperature requirements still make SQUIDS the preferable option.
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Article Abstract:
A quantum well has been designed that can entrap electrons even when they pass completely over it. Federico Capasso and colleagues relied on advances in materials science to construct a quantum well based on a semiconductor heterostructure; the well uses mirrors to produce a bound state above the well. The electrons' trapped state was observed by optically exciting electrons from a lower, bound state of the wide well. New forms of semiconductors could result from this finding.
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