Researchers Transform the Properties of Matter With Tunable Quantum Dots

Researchers at the University of Pennsylvania have turned lead and selenium nanocrystals into solids with remarkable physical properties.  The Penn physicists are among many researchers who have been experimenting with a different way of transforming matter through artificial solids, formed from closely packed nanoscale crystals, also called "quantum dots."    

Artificial solids, in general, are constructed by specifically assembling a number of nanocrystals, each composed of only a few thousand atoms, into a closely packed and well-ordered lattice.  Previous researchers have demonstrated that quantum dots can be manipulated to change their physical properties, particularly their optical properties.  In fact, the blue laser, which will soon be put into use into commercial products, was a result of early research in changing the colors of quantum dots.   

In their study, the researchers looked at the ability of artificial solids to transport electrons.  They demonstrated that, by controlling the coupling of artificial atoms within the crystal, they could increase the electrical conductivity of the entire crystal.

According to the researchers, this system promises the possibility of designing artificial solids that can be switched through a variety of electronic phase transitions, with little influence from the local environment. Their findings represent a key step towards the fabrication of functional nanocrystal-based devices and circuits.

Quantum dots are more than simply analogous to individual atoms; they also demonstrate quantum effects, like atoms, but on a larger scale.  As a tool for research, quantum dots make it possible for physicists to measure, firsthand, some things only described in theory.   

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