Scientists Discover New Electronic State of Matter

A team of U.S. physicists and materials scientists has observed a new state of matter at the interface between two oxide materials: lanthanum aluminate (LaAlO₃) and strontium titanate (SrTiO₃). The discovery shows electrons can bind together in ways similar to how quarks combine to form neutrons and protons.

Electrons travel in cars with increasing numbers, giving rise to a conductance series that shows up in Pascal’s triangle. Image credit: Yun-Yi Pai.

“Normally, electrons in semiconductors or metals move and scatter, and eventually drift in one direction if you apply a voltage,” explained co-lead author Professor Jeremy Levy, a researcher in the Department of Physics and Astronomy at the University of Pittsburgh and the Pittsburgh Quantum Institute.

“But in ballistic conductors the electrons move more like cars on a highway.”

“The advantage of that is they don’t give off heat and may be used in ways that are quite different from ordinary electronics.”

“The discovery we made shows that when electrons can be made to attract one another, they can form bunches of two, three, four and five electrons that literally behave like new types of particles, new forms of electronic matter,” he said.

It’s similar to the way in which quarks bind together to form neutrons and protons.

An important clue to uncovering the new matter was recognizing that these ballistic conductors matched a sequence within Pascal’s triangle.

“If you look along different directions of Pascal’s triangle you can see different number patterns and one of the patterns was one, three, six, 10, 15, 21,” Professor Levy said.

“This is a sequence we noticed in our data, so it became a challenging clue as to what was actually going on.”

“The discovery took us some time to understand but it was because we initially did not realize we were looking at particles made up of one electron, two electrons, three electrons and so forth. If you combine all this together you get the sequence of 1, 3, 6, 10.”

“The new particles feature properties related to quantum entanglement, which can potentially be used for quantum computing and quantum redistribution,” he added.

“The discovery is an exciting advancement toward the next stage of quantum physics.”

The findings were published in the journal Science.

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Megan Briggeman et al. 2020. Pascal conductance series in ballistic one-dimensional LaAlO₃/SrTiO₃ channels. Science 367 (6479): 769-772; doi: 10.1126/science.aat6467