Dr. Jukka Vayrynen was a post-doctoral researcher looking at a theoretical model featuring emergent particles in a condensed matter environment before he became an assistant professor at the Purdue Department of Physics and Astronomy.
He planned to develop the model after he got to Purdue, anticipating it to be quite simple. He gave the seemingly straightforward calculations to Guangjie Li, a graduate student working with Vayrynen, but the calculations yielded an unexpected result.
Their findings were a startling hurdle that nearly put an end to their investigation. This obstacle has been used by Team Tenacity to create a potential path toward the creation of quantum computing.
At the Aspen Center for Physics in Colorado, Vayrynen discussed this issue with a colleague from the Weizmann Institute of Science in Israel, Dr. Yuval Oreg, who helped circumvent the obstacle.
The team constructed a quantum device that could be tested experimentally to quickly realize emergent particles like the Fibonacci anyon using this new understanding of their computations. They have published their findings, “Multichannel topological Kondo effect,” in Physical Review Letters on February 10, 2023.
Condensed matter theory is a branch of physics with applications to superconductors, transistors, and quantum computer devices. It analyzes, for instance, the characteristics of electronic quantum systems.
We evaluate the zero-temperature impurity entropy and conductance to obtain experimentally observable signatures of our results. In the large-N limit we evaluate the full cross-over function describing the temperature-dependent conductance.
Dr. Jukka Vayrynen
One of the challenges in this field is understanding the quantum mechanical behavior of many electrons, also known as the “many-body problem.” It is a problem because it can only be theoretically modeled in very limited cases.
Even in those rare instances, rich emergent phenomena have been observed, such as collective excitations or emerging “quasi”-particles that are fractionally charged. These occurrences, which are the outcome of intricate interactions between electrons, have the potential to result in the creation of novel materials and technology.
“In our paper, we propose a quantum device that is simple enough to be theoretically modeled and tested experimentally in the future, yet also complex enough to display non-trivial emergent particles,” says Vayrynen.
“Our results indicate that the proposed device can realize an emergent particle called a Fibonacci anyon that can be used as a building block of a quantum computer. The device is therefore a promising candidate for the development of quantum computing technology.”
This discovery could be used in future quantum computers in a way that allows one to make them more resistant to decoherence, a.k.a. noise.
According to their publication, the team introduced a physically motivated N-channel generalization of a topological Kondo model. Starting from the simplest case N = 2, they conjecture a stable intermediate coupling fixed point and evaluate the resulting low-temperature impurity entropy. The impurity entropy indicates that an emergent Fibonacci anyon can be realized in the N = 2 model.
According to Li, “a Fibonacci anyon is an emergent particle with the property that as you add more particles to the system, the number of quantum states grows like the Fibonacci sequence, 1, 2, 3, 5, 8, etc. In our system, a small quantum device is connected to conduction electron leads which will overly screen the device and can result in an emergent Fibonacci anyon.”
The group also makes a number of predictions that might be put to the test experimentally in upcoming quantum devices.
“We evaluate the zero-temperature impurity entropy and conductance to obtain experimentally observable signatures of our results. In the large-N limit we evaluate the full cross-over function describing the temperature-dependent conductance,” says Vayrynen.
This research is the first in a series that the Purdue team of Li and Vayrynen will work on. They collaborated with a senior scientist from Max Planck Institute for Solid State Research in Germany, Dr. Elio König, and posted a related work, “Topological Symplectic Kondo Effect,” in a preprint arXiv (2210.16614) on October 20, 2022.
This research was based on work supported by the Quantum Science Center, a U.S. Department of Energy National Quantum Information Science Research Center headquartered at DOE’s Oak Ridge National Laboratory.
Dr. Yong Chen, the Karl Lark-Horovitz Professor of Physics and Astronomy and Professor of Electrical and Computer Engineering, is on the QSC’s Governance Advisory Board, and Purdue is one of the center’s core partners.
