Illustration of sketched serpentine nanowires created from lanthanum aluminate and strontium titanate. The side-to-side motion of the electrons as they travel gives them additional properties that can be used to make quantum devices. Image: Jeremy Levy.A research team led by professors from the Department of Physics and Astronomy at the University of Pittsburgh have created a serpentine path for electrons in nanowires made from a metal oxide, imbuing the electrons with new properties that could be useful in future quantum devices. Jeremy Levy, a distinguished professor of condensed matter physics, and Patrick Irvin, a research professor, are co-authors of a paper on this work in Science Advances.
"We already know how to shoot electrons ballistically through one-dimensional nanowires made from these oxide materials," explains Levy. "What is different here is that we have changed the environment for the electrons, forcing them to weave left and right as they travel. This motion changes the properties of the electrons, giving rise to new behavior."
The work is led by a recent PhD recipient, Megan Briggeman, whose thesis was devoted to the development of a platform for 'quantum simulation' in one dimension. Briggeman is also the lead author on a related paper published earlier this year in Science, where a new family of electronic phases was discovered in which electrons travel in packets of two, three and more at a time.
Electrons behave very differently when forced to travel along a straight line (i.e. in one dimension). It is known, for example, that the spin and charge components of electrons can split apart and travel at different speeds through a 1D wire. These bizarre effects are fascinating and also important for the development of advanced quantum technologies such as quantum computers.
Motion along a straight line is just one of a multitude of possibilities that can be created using this quantum simulation approach. This latest paper explores the consequences of making electrons weave side to side while they are racing down an otherwise linear path.
One recent proposal for topologically protected quantum computation takes advantage of so-called 'Majorana fermions', particles that can exist in 1D nanowires when certain interactions are present. Nanowires made of lanthanum aluminate and strontium titanate (LaAlO3/SrTiO3) possess most but not all of the required interactions. Missing is a sufficiently strong 'spin-orbit interaction' that can produce the conditions for Majorana fermions. One of the main findings of this latest work from Levy is that spin-orbit interactions can in fact be engineered by fabricating nanowires with a slalom path, thereby forcing the electrons to adopt a serpentine motion as they travel along them.
In addition to identifying new engineered spin-orbit couplings, the periodic repetition of the serpentine path creates new ways for electrons to interact with one another. The experimental result of this is the existence of fractional conductances that deviate from those expected for single electrons.
These slalom paths are created using a nanoscale sketching technique analogous to an Etch A Sketch toy, but with a point size that is a trillion times smaller in area. These paths can be sketched and erased over and over, each time creating a new type of path for electrons to traverse. This approach can be thought of as a way of creating quantum materials with re-programmable properties.
Materials scientists synthesize materials in a similar fashion, drawing atoms from the periodic table and forcing them to arrange in periodic arrays. Here the array is artificial – one zig-zag of the motion takes place in a 10nm space rather than a sub-nanometer atomic distance.
Levy, who is also director of the Pittsburgh Quantum Institute, stated that this work contributes to one of the main goals of the second quantum revolution, which is to explore, understand and exploit the full nature of quantum matter. An improved understanding, and the ability to simulate the behavior of a wide range of quantum materials, will have wide-ranging consequences.
"This research falls within a larger effort here in Pittsburgh to develop new science and technologies related to the second quantum revolution," he said.
This story is adapted from material from the University of Pittsburgh, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.