HOUSTON (Nov. 25, 2013) Spontaneous bursts of light from a solid block illuminate the unusual way interacting quantum particles behave when they are driven far from equilibrium. The discovery by Rice University scientists of a way to trigger these flashes may lead to new telecommunications equipment and other devices that transmit signals at picosecond speeds.
The Rice University lab of Junichiro Kono found the flashes, which last trillionths of a second, change color as they pulse from within a solid-state block. The researchers said the phenomenon can be understood as a combination of two previously known many-body concepts: superfluorescence, as seen in atomic and molecular systems, and Fermi-edge singularities, a process known to occur in metals.
The team previously reported the first observation of superfluorescence in a solid-state system by strongly exciting semiconductor quantum wells in high magnetic fields. The new process Fermi-edge superfluorescence does not require them to use powerful magnets. That opens up the possibility of making compact semiconductor devices to produce picosecond pulses of light.
The results by Rice, Florida State University and Texas A&M University researchers were reported this month in Nature's online journal, Scientific Reports.
The semiconducting quantum wells at the center of the experiment contain particles in this case, a dense collection of electrons and holes and confine them to wiggle only within the two dimensions allowed by the tiny, stacked wells, where they are subject to strong Coulomb interactions.
Previous experiments by Rice and Florida State showed the ability to create superfluorescent bursts from a stack of quantum wells excited by a laser in extreme cold and under the influence of a strong magnetic field, both of which further quenched the electrons' motions and made an atom-like system. The basic features were essentially the same as th
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