Tuning Quantum States of Matter Using Ultrafast Photonics

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AMES, Iowa, Aug. 23, 2019 — Researchers at Iowa State University, led by professor Jigang Wang, are using quantum terahertz spectroscopy to explore and control quantum states of matter. The researchers have announced three discoveries based on their studies.

The first, reported in Nature Materials, describes how ultrafast pulses of photons — pulsed at trillions of cycles per second — can switch on a state of matter hidden by the superconductive flow of electricity at ultracold temperatures. The researchers demonstrated a tuning knob for switching on exotic, hidden states without changing the temperature. Such a tuning knob, called a quantum quench, could further the research and discovery of nonequilibrium materials.

The second finding, reported in Physical Review Letters, describes how the group’s terahertz instrumentation traced electron pairings in materials, revealing a new, light-induced, long-lived state of matter.

The third discovery, reported in Nature Photonics, describes how ultrafast pulses of photons can be used like a tuning knob to control and accelerate supercurrents. The ultrafast light pulses break equilibrium symmetry, triggering quantum oscillations that, according to the researchers, cannot be achieved by any other means.

Jigang Wang and his research group use quantum terahertz spectroscopy to access, study, and control quantum states of matter. Courtesy of Christopher Gannon/Iowa State University.

Jigang Wang and his research group use quantum terahertz spectroscopy to access, study, and control quantum states of matter. The research group, (l) to (r): Zhaoyu Liu, Liang Luo, Chirag Vaswani, Di Cheng, Jigang Wang, Dinusha Mudiyanselage, Richard H. Kim, and Chuankun Huang. Courtesy of Christopher Gannon/Iowa State University. 

Wang said that the team would like to use these ultrafast pulses and high frequencies of light to probe smaller scales, in the 1 to 10 nm range. “We’d also like to develop controls using terahertz light for the quantum computation community,” he said.

Wang believes that the intense terahertz flashes produced by his laboratory instruments can be a control knob for finding, stabilizing, probing, and potentially controlling exotic states and their unique properties. “We have established a new approach to access and potentially control exotic states of matter,” he said.

The research was published in Nature Materials (, Physical Review Letters (, and Nature Photonics (


Published: August 2019
The term quantum refers to the fundamental unit or discrete amount of a physical quantity involved in interactions at the atomic and subatomic scales. It originates from quantum theory, a branch of physics that emerged in the early 20th century to explain phenomena observed on very small scales, where classical physics fails to provide accurate explanations. In the context of quantum theory, several key concepts are associated with the term quantum: Quantum mechanics: This is the branch of...
Terahertz (THz) refers to a unit of frequency in the electromagnetic spectrum, denoting waves with frequencies between 0.1 and 10 terahertz. One terahertz is equivalent to one trillion hertz, or cycles per second. The terahertz frequency range falls between the microwave and infrared regions of the electromagnetic spectrum. Key points about terahertz include: Frequency range: The terahertz range spans from approximately 0.1 terahertz (100 gigahertz) to 10 terahertz. This corresponds to...
Research & TechnologyeducationAmericasIowa State UniversityThe Ames LaboratoryLight SourcesMaterialsOpticsspectroscopyLaserspulses lasersultrafast lasersquantumterahertzexotic states of matterultrafast photonics

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