MIT physicists propose a method to create fractionalized electrons known as non-Abelian anyons in two-dimensional materials, potentially advancing quantum computing by enabling more reliable quantum bits without using magnetic fields.
Their research highlights the potential of molybdenum ditelluride in forming these anyons, promising significant advancements in robust quantum computation.
MIT Physicists Predict Exotic Matter for Quantum Computing
MIT physicists have shown that it should be possible to create an exotic form of matter that could serve as the building blocks for future quantum computers. These quantum bits, or qubits, could make quantum computers even more powerful than those in development today.
Their research builds on a recent discovery of materials where electrons can split into fractional parts — a phenomenon known as electron fractionalization. Crucially, this splitting happens without the need for a magnetic field, making the process more practical for real-world applications.
Advances in Electron Fractionalization
Electron fractionalization was first discovered in 1982, earning a Nobel Prize, but the original process required applying a magnetic field. The ability to create fractionalized electrons without this requirement opens the door to new research possibilities and practical technological uses.
When electrons split into fractions of themselves, those fractions are known as anyons. Anyons come in variety of flavors, or classes. The anyons discovered in the 2023 materials are known as Abelian anyons. Now, in a paper published recently in the journal Physical Review Letters, the MIT team notes that it should be possible to create the most exotic class of anyons, non-Abelian anyons.
Exploring Non-Abelian Anyons
“Non-Abelian anyons have the bewildering capacity of ‘remembering’ their spacetime trajectories; this memory effect can be useful for quantum computing,” says Liang Fu, a professor in MIT’s Department of Physics and leader of the work.
Fu further notes that “the 2023 experiments on electron fractionalization greatly exceeded theoretical expectations. My takeaway is that we theorists should be bolder.”
Fu is also affiliated with the MIT Materials Research Laboratory. His colleagues on the current work are graduate students Aidan P. Reddy and Nisarga Paul, and postdoc Ahmed Abouelkomsan, all of the MIT Department of Phsyics. Reddy and Paul are co-first authors of the Physical Review Letters paper.
Implications for Quantum Computing
The MIT work and two related studies were also featured in an recent story in Physics Magazine. “If this prediction is confirmed experimentally, it could lead to more reliable quantum computers that can execute a wider range of tasks … Theorists have already devised ways to harness non-Abelian states as workable qubits and manipulate the excitations of these states to enable robust quantum computation,” writes Ryan Wilkinson.
The current work was guided by recent advances in 2D materials, or those consisting of only one or a few layers of atoms. “The whole world of two-dimensional materials is very interesting because you can stack them and twist them, and sort of play Legos with them to get all sorts of cool sandwich structures with unusual properties,” says Paul. Those sandwich structures, in turn, are called moiré materials.
Moiré Materials and Quantum Potential
Anyons can only form in two-dimensional materials. Could they form in moiré materials? The 2023 experiments were the first to show that they can. Soon afterward, a group led by Long Ju, an MIT assistant professor of physics, reported evidence of anyons in another moiré material. (Fu and Reddy were also involved in the Ju work.)
In the current work, the physicists showed that it should be possible to create non-Abelian anyons in a moiré material composed of atomically thin layers of molybdenum ditelluride. Says Paul, “moiré materials have already revealed fascinating phases of matter in recent years, and our work shows that non-Abelian phases could be added to the list.”
Adds Reddy, “Our work shows that when electrons are added at a density of 3/2 or 5/2 per unit cell, they can organize into an intriguing quantum state that hosts non-Abelian anyons.”
Connecting Theory and Practice
The work was exciting, says Reddy, in part because “oftentimes there’s subtlety in interpreting your results and what they are actually telling you. So it was fun to think through our arguments” in support of non-Abelian anyons.
Says Paul, “This project ranged from really concrete numerical calculations to pretty abstract theory and connected the two. I learned a lot from my collaborators about some very interesting topics.”
Reference: “Non-Abelian Fractionalization in Topological Minibands” by Aidan P. Reddy, Nisarga Paul, Ahmed Abouelkomsan and Liang Fu, 17 October 2024, Physical Review Letters.
DOI: 10.1103/PhysRevLett.133.166503
This work was supported by the U.S. Air Force Office of Scientific Research. The authors also acknowledge the MIT SuperCloud and Lincoln Laboratory Supercomputing Center, the Kavli Institute for Theoretical Physics, the Knut and Alice Wallenberg Foundation, and the Simons Foundation.
