New state of matter discovered that could lead to better quantum engineering

Using intense lasers with extremely short pulses in a way equivalent to strobe photography, theoretical and computational physicists at the University of Alabama at Birmingham collaborated with experimentalists at Ames National Lab and Iowa State University to catch and visualize electrons in a high-temperature iron-based superconducting material, which interact as a new state of matter not observed in equilibrium.

Switching on this state of matter with its unusual, quantum properties takes intense laser pulses, like a flash, hitting the cooled superconductor. Then, a second light pulse triggers an ultrafast camera to take images of this state and observe collective behaviors competing with superconductivity that, when fully understood and tuned, could one day have implications for faster, heat-free, quantum computing, information storage and communication — or what is called “quantum engineering.”

“The discovery of this new switching scheme and quantum state was full of challenges,” said Ilias Perakis, Ph.D., chair of the UAB College of Arts and Sciences Department of Physics. “To find new emergent electron matter beyond solids, liquids and gases, today’s condensed matter physicists can no longer fully rely on traditional, slow, thermodynamic tuning knobs such as changing temperatures, pressures, chemical compositions or magnetic fields.”

The UAB advanced computation team of postdoctoral research fellow Martin Mootz, Ph.D., and Perakis developed a model and simulations that made it possible for Jigang Wang’s laser spectroscopy group at Iowa State University and the United States Department of Energy’s Ames Laboratory to identify the experimental signatures of the new quantum state. The experimental signatures were driven by intense laser excitation and are not observed in equilibrium.

Conducting electricity without resistance

The new switching scheme developed by this collaboration uses short pulsed light particles to selectively bombard the superconductor energy gap for less than a trillionth of a second. This suddenly switches the superconductor, which at ultracold temperatures can conduct electricity without resistance, to a state of matter not observed under equilibrium conditions.

The scientific journal Physical Review Letters recently published a paper describing this discovery. This paper follows a recent publication in the journal Nature Materials and is part of an ongoing project funded by the U.S. Department of Energy. In most cases, exotic states of matter such as the one described in this research paper are unstable and short-lived. In this case, the state of matter is metastable, or without decay to a stable state for an order of magnitude longer than conventional equilibration pathways.

A remaining challenge for the researchers is to figure out how to control and further stabilize the hidden state, and whether this is suitable for the implementation, for example, of quantum logic operations. That could enable researchers to apply and even harness coherence and dynamics of the hidden state for practical functions — such as quantum computing — and for fundamental tests of bizarre quantum mechanics phenomena now used for “quantum engineering.”

“We aim to create a sustainable innovation and entrepreneurship ecosystem in Birmingham, powered by UAB research and education on advanced materials and computation, and necessary for enabling the ‘Silicon Valley of the South’ sometime in the near future,” Perakis said. “Today, almost all technologies that underpin the global economy and health care depend on advanced materials and computation, in one way or the other.”

Engine of progress

Perakis states that the discovery and understanding of new quantum materials with unique properties is an engine of progress for Birmingham and the nation as a whole. Demand for novel materials designed to respond in desired ways under extreme conditions and external stimuli is rapidly rising for applications in key technologies and industries.

For example, the very recent launch of a National Quantum Initiative by President Donald Trump and Congress recognizes that multifunctional devices based on “quantum phenomena” will be an engine for future economic growth. Quantum phenomena are already being incorporated into technologies for next-generation computers, sensors and detectors that demonstrate superior performance characteristics.

Quantum device capabilities envisioned include enhanced resolution in imaging, sensors and detectors; advanced cryptography for more secure communication; and significantly larger computational capabilities at speeds far greater than those possible at present. These and other advances require a more detailed interdisciplinary effort to understand how materials behave under extreme and non-equilibrium conditions. This is the focus of the UAB Department of Physics, supported by a grant from the U.S. Department of Energy and others.



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