Engineering 101

Controlling Quantum Matter: Is It Possible?

By Dawn Allcot


Jigang Wang’s goal is not to “seek out new life and new civilizations,” as the starship crew in a classic science fiction show once aimed to accomplish.

Instead, the professor at Iowa State University and physicist at the U.S. Department of Energy’s Ames Laboratory has set his sights on discoveries much larger – and at the same time, quantifiably smaller.

Wang wants to “discover and control quantum states of matter.”

Jigang Wang and his research group use quantum terahertz spectroscopy to access, study and control quantum states of matter.

Why does this matter? Harnessing quantum physics – the particles and energy at atomic scales – could lead to better computing, sensing, communications, and data storage technologies.

Through a 3-year, $465,000 grant from the U.S. Army Research Office, Wang is using quantum terahertz spectroscopy that can visualize and steer electrons to learn more than anyone has ever known about quantum physics.

Several collaborators have contributed to Wang’s discoveries, including the Ilias E. Perakis group at the University of Alabama at Birmingham contributed theoretical simulations; the Chang-Beom Eom group at the University of Wisconsin-Madison and the Paul Canfield group at Iowa State, which contributed high-quality superconducting materials and their characterizations.

In the journal Nature Materials, Wang and his team describe how ultrafast pulses of photons – laser flashes at trillions of cycles per second – can switch on a state of matter hidden by superconductivity, the flow of electricity without resistance, usually at super-cold temperatures. The discovery demonstrates a new tuning knob – called “quantum quench” by the physicists – for non-equilibrium materials discovery such as switching on exotic, hidden states without temperature change.

In Physical Review Letters, the physicists share how the terahertz instrumentation can trace electron pairings in materials, revealing a new, light-induced, long-lived state of matter.

Finally, a report in Nature Photonics describes how the ultrafast flashes of light Wang and his collaborators work with can be used like a knob to control and accelerate supercurrents. The flashes break equilibrium symmetry, triggering forbidden quantum oscillations that can’t be achieved by other means.

Through his research, Wang aims to develop and apply precise and powerful laboratory tools in a controlled, rational way to find new states of matter hidden within superconducting and other complex materials.

Wang has learned that the intense terahertz flashes produced by his laboratory instruments can act as a control knob for finding, stabilizing, probing — and potentially controlling — these exotic states and their unique properties.

“We have established a new approach,” Wang said, “to access and potentially control exotic states of matter.”

Source: Iowa State University

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