Physicists have discovered new states of matter by investigating the behavior of electrons in a two-dimensional flatland under extreme conditions. This research may have significant implications for advancements in quantum computing and innovative materials.
Picture a two-dimensional flatland where the rules of physics are entirely different from our three-dimensional environment, allowing particles like electrons to behave unexpectedly and reveal new secrets. This is precisely what a group of researchers led by Ramesh G. Mani, a Professor of Physics at Georgia State University, along with recent Ph.D. graduate U. Kushan Wijewardena, have been exploring in their laboratory at Georgia State.
Their groundbreaking work was recently published in the journal Communications Physics. The researchers focused on the intriguing fractional quantum Hall effects (FQHE), uncovering new and surprising phenomena when these systems are examined in innovative ways and pushed past conventional limits.
“The study of fractional quantum Hall effects has captivated condensed matter physics researchers for decades since particles in flatland can exhibit multiple behaviors depending on the context,” Mani explained. “Our latest discoveries expand the horizons of this field, providing fresh insights into these intricate systems.”
The quantum Hall effect has been an essential area in condensed matter physics since its discovery in 1980 by Klaus von Klitzing, who found that simple electrical measurements could yield highly accurate values for fundamental constants related to the universe’s behavior. This remarkable achievement earned him a Nobel Prize in 1985.
In 1998, the Nobel Prize was awarded for the discovery and understanding of the fractional quantum Hall effect, which indicated that particles in flatland could possess fractional charges. The research continued with the advent of graphene, a material that indicated the presence of massless electrons in flatland, resulting in yet another Nobel Prize in 2010.
Most recently, theories surrounding new phases of matter linked to the quantum Hall effect were awarded a Nobel Prize in 2016.
Condensed matter physics has led to significant discoveries, paving the way for modern electronics such as cellphones, computers, GPS, LED lights, solar panels, and even autonomous vehicles. Research into flatland science and materials in condensed matter physics aims to develop more energy-efficient, flexible, rapid, and lightweight electronics, including innovative sensors, higher efficiency solar panels, and advanced quantum computers.
Through a series of experiments conducted at extremely low temperatures, near -459°F (-273°C), and under an intense magnetic field nearly 100,000 times stronger than Earth’s, Mani, Wijewardena, and their team began their work. They applied an additional current to high-mobility semiconductor devices created from a layered structure of gallium arsenide (GaAs) and aluminum gallium arsenide (AlGaAs). This setup enabled them to observe electrons in a flatland context. They found that all FQHE states split unexpectedly, leading to crossings of these split branches, which allowed them to investigate new non-equilibrium states within these quantum systems and discover completely new states of matter. The success of this research was significantly aided by the production of high-quality crystals at the Swiss Federal Institute of Technology Zurich, led by Professors Werner Wegscheider and Christian Reichl.
“Consider traditional studies of fractional quantum Hall effects as exploring the ground level of a building,” Mani said. “Our research involves searching for and discovering the higher levels—those thrilling, uncharted territories—and understanding what they entail. Remarkably, we could access these upper levels with a straightforward technique, unveiling complex signatures of the excited states.”
Wijewardena, who received his Ph.D. in physics from Georgia State last year and is currently a faculty member at Georgia College and State University in Milledgeville, shared his enthusiasm about their findings.
“We’ve invested years researching these phenomena, but this is the first time we’ve reported experimental results confirming the excitation of fractional quantum Hall states through the application of a direct current bias,” Wijewardena said. “The outcomes are compelling, and it took considerable time to develop a plausible explanation for our observations.”
With support from the National Science Foundation and the Army Research Office, the study challenges existing theories and proposes a hybrid origin for the observed non-equilibrium excited-state FQHEs. This innovative approach and the unexpected findings underscore the potential for new breakthroughs in condensed matter physics, encouraging future research and technological innovations.
The implications of the team’s discoveries extend well beyond the laboratory, offering crucial insights that could enhance quantum computing and materials science. By probing these uncharted domains, the researchers are laying the foundation—and mentoring new generations of students—for future technologies that could transform everything from data processing to energy efficiency, fueling the high-tech economy.
Mani, Wijewardena, and their team are now expanding their research into even more extreme conditions, pursuing new techniques to measure complex flatland parameters. As they advance, they expect to uncover even more complexities in these quantum systems, contributing essential insights to the field. With each experiment, the team draws closer to deciphering the intricate behaviors at play, remaining open to the potential of new discoveries along the way.
