An international effort to quantify wave-particle duality in photons that originated with a Texas A&M University scientist in 2020 has been honored as a Physics World Top 10 Breakthrough of 2021.
The Institute for Basic Science in South Korea’s Tai Hyun Yoon and Minhaeng Cho and the Stevens Institute of Technology’s Xiaofeng Qian were cited by the internationally renowned IOP Publishing journal along with Texas A&M physicist Girish S. Agarwal for an intriguing combination of experimental and theoretical work that quantified the “wave-ness” and “particle-ness” of a photon and also demonstrated that both properties are related to the purity of the photon source.
According to a Physics World press release, Yoon and Cho were able to tightly control the quantum state of pairs of photons — a “signal” and an “idler” — emitted by two crystals of lithium niobate. By independently altering the chances that each crystal would emit photons, they showed that this so-called source purity is related to the visibility of interference fringes (a wave-like property) and path distinguishability (a particle-like property) by a simple mathematical expression that was first articulated by Qian and Agarwal in 2020. The result has applications in quantum information and puts a new twist on interpretations of complementarity — an idea first articulated by 20th century quantum pioneer Niels Bohr positing that quantum objects sometimes behave like waves and at other times like particles.
“This was a great achievement, that they could produce a single photon state where all the parameters were at their control,” Agarwal said about Yoon and Cho’s experiments, which were first published in Science Advances last August.
The team’s pioneering work earned selection as one of the top 10 finalists for the Physics World 2021 Breakthrough of the Year, unveiled in a December 14 announcement issued by the journal as quantum entanglement of two macroscopic objects. The 10 research projects were chosen by five Physics World editors from a list of nearly 600 research updates published on the website this year.
“Girish Agarwal and his associates apply quantum science to improve microscopy and spectroscopy, ushering in a life-science resolution revolution,” said Texas A&M Distinguished Professor of Physics Dr. Marlan O. Scully, a longtime colleague of Agarwal’s who helped to recruit him to Texas A&M five years ago.
Agarwal joined the Texas A&M faculty in September 2016 as a professor in the Department of Biological and Agricultural Engineering and the Department of Physics and Astronomy and a member of the Institute for Quantum Science and Engineering. He was one of the 10 initial faculty — including five at Texas A&M — recruited to the state of Texas through the Governor’s University Research Initiative. Prior to coming to Texas A&M, Agarwal served as the Noble Foundation Chair and a Regents Professor at Oklahoma State University, where he was recognized with the Eminent Faculty Award in 2012. His research spans both the theoretical and experimental realms of quantum optics, in particular, the interaction of laser light with atoms and development of bio-photonics technologies and applications to identify and detect chemical compounds and pathogens at a distance.
In addition to being a globally recognized leader in quantum optics, Agarwal also has made major contributions to the fields of nonlinear optics, nanophotonics and plasmonics. His 2013 textbook “Quantum Optics” covers a wide range of recent developments in the field and has been well received by the community.
Agarwal is a fellow of the Royal Society (2008), World Academy of Sciences (1997), Optical Society of America (1986) and American Physical Society (1981) as well as the National Academy of Sciences, India, Allahabad (1988), Indian National Science Academy, New Delhi (1985) and Indian Academy of Sciences, Bangalore (1981). In addition, he is an honorary fellow of the Indian Association for Cultivation of Science, Kolkata (2008). His many career awards include the Humboldt Research Award (1997), the Optical and Quantum Electronics Society’s Einstein Medal (1994), the Third World Academy of Sciences Prize in Physics (1994), the OSA’s Max-Born Award (1988) and the Government of India’s Shanti Swaroop Bhatnagar Award in Physical Sciences (1982).
Learn more about the Physics World 2021 Breakthrough of the Year as well as the 10 finalists, all of which are discussed in the December 9 edition of the Physics World Weekly podcast.
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