Physicists Discover New Semiconductor Quasiparticle Called Quantum Droplet

Posted on February 27, 2014

JILA physicists have discovered a new semiconductor quasiparticle called the quantum droplet. JILA is a joint institute of University of Colorado Boulder and the National Institute of Standards and Technology (NIST). The researchers used an ultrafast laser and help from German theorists to discover it. The new quasiparticle was created by exciting a gallium-arsenide semiconductor with an ultrafast red laser emitting about 100 million pulses per second. The quantum droplet has a lifetime of just 25 picoseconds (trillionths of a second). An artist's concept of the quantum droplet is pictured above.

The researchers say the new quasiparticle is a "microscopic complex of electrons and holes in a new, unpaired arrangement." They are calling it a quantum droplet because it has both quantum characteristics and liquid characteristics. It has well-ordered energy levels, a quantum characteristic, but it also has ripples like a liquid. The researchers say the quantum droplet also differs from a liquid because it "has a finite size, beyond which the association between electrons and holes disappears."

JILA physicist Steven Cundiff says in a statement, "Electron-hole droplets are known in semiconductors, but they usually contain thousands to millions of electrons and holes. Here we are talking about droplets with around five electrons and five holes. Regarding practical benefits, nobody is going to build a quantum droplet widget. But this does have indirect benefits in terms of improving our understanding of how electrons interact in various situations, including in optoelectronic devices."

A research paper on the new quasiparticle was published here in Nature.

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