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Terahertz Field Stabilizes Surface State of Topological Materials

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AMES, Iowa, March 4, 2020 — Some topological materials are insulators in their bulk form but possess electron-conducting behavior on their surfaces. The contrast in the behavior of these surface electrons is promising for future applications but challenging to control. Uncontrolled interactions between surface electrons and the bulk material states can cause electrons to scatter out of order, leading to “topological breakdown.”

Scientists at the U.S. Department of Energy’s Ames Laboratory found that applying vibrational motion in a periodic manner could help prevent dissipation of the surface electron states.

Using an approach called dynamic stabilization the researchers demonstrated that coherent lattice vibrations periodically driven by a single-cycle terahertz (THz) pulse could significantly suppress dissipation in topological materials. They applied a THz electric field to drive periodic atomic vibrations, that is, vibrational coherence, in a bismuth-selenium (Bi2Se3) topological insulator model. The additional vibrations actually enhanced protected topological states, prolonging the lifetime of the electronic excitations.

Ames Laboratory scientists used dynamic stabilization, applying a terahertz electric field to drive periodic lattice oscillations in a model topological insulator. These additional fluctuations actually enhanced protected topological states. Courtesy of U.S. Department of Energy, Ames Laboratory.
Ames Laboratory scientists used dynamic stabilization, applying a terahertz electric field to drive periodic lattice oscillations in a model topological insulator. These additional fluctuations actually enhanced protected topological states. Courtesy of U.S. Department of Energy, Ames Laboratory.


The researchers believe that imposing vibrational quantum coherence into topological states of matter could become a universal light control principle for reinforcing symmetry-protected helical transport.

“Topological insulators that can sustain a persistent spin-locked current on their surfaces which does not decay are termed ‘symmetry protected,’ and that state is compelling for multiple revolutionary device concepts in quantum computing and spintronics,”said Jigang Wang, Ames Laboratory physicist and Iowa State University professor. “We demonstrate the dynamic stabilization in topological matter as a new universal tuning knob that can be used to reinforce protected quantum transport.”

The discovery could influence the use of topological materials for many scientific and technological disciplines, such as disorder-tolerant quantum information and communications applications and spin-based, lightwave quantum electronics.

The research was published in npj Quantum Materials (www.doi.org/10.1038/s41535-020-0215-7). 

Published: March 2020
Glossary
quantum
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...
optoelectronics
Optoelectronics is a branch of electronics that focuses on the study and application of devices and systems that use light and its interactions with different materials. The term "optoelectronics" is a combination of "optics" and "electronics," reflecting the interdisciplinary nature of this field. Optoelectronic devices convert electrical signals into optical signals or vice versa, making them crucial in various technologies. Some key components and applications of optoelectronics include: ...
terahertz
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...
quantum optics
The area of optics in which quantum theory is used to describe light in discrete units or "quanta" of energy known as photons. First observed by Albert Einstein's photoelectric effect, this particle description of light is the foundation for describing the transfer of energy (i.e. absorption and emission) in light matter interaction.
Research & TechnologyeducationAmericasIowa State UniversityAmes LaboratoryLight SourcesMaterialstopological materialsquantumQuantum Materialsoptoelectronicstopological insulatorsCommunicationsterahertzultrafast photonicsquantum opticstopological breakdownspintronics

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