{"id":296512,"date":"2026-01-21T22:11:14","date_gmt":"2026-01-21T22:11:14","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/296512\/"},"modified":"2026-01-21T22:11:14","modified_gmt":"2026-01-21T22:11:14","slug":"physicists-have-achieved-quantum-alchemy-by-exciting-electrons-to-high-energy-states","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/296512\/","title":{"rendered":"Physicists Have Achieved Quantum \u201cAlchemy\u201d by Exciting Electrons to High-Energy States"},"content":{"rendered":"

A promising\u2014and powerful\u2014new engineering breakthrough could soon enable researchers to alter the properties of materials by exciting electrons to higher-than-normal energy<\/a> levels.<\/p>\n

In physics, Floquet engineering involves changes in the properties of a quantum material<\/a> induced by a driving force, such as high-powered light. The resulting effect causes the material\u2019s behavior to change, introducing novel quantum states with properties that do not occur under normal conditions.<\/p>\n

Given its promising applications, Floquet engineering has remained of interest to researchers for many years. Now, a team of scientists from the Okinawa Institute of Science and Technology (OIST) and Stanford University says they have developed a new method for achieving Floquet physics that is more efficient than past methods that rely on light<\/a>.<\/p>\n

21st Century Alchemy? <\/strong><\/p>\n

Professor Keshav Dani, a researcher with OIST\u2019s Femtosecond Spectroscopy Unit, said in a statement<\/a> announcing the breakthrough that the team\u2019s new approach leverages what are known as excitons<\/a>, which have proven far more powerful in coupling with quantum materials than existing methods \u201cdue to the strong Coulomb interaction, particularly in 2D materials.\u201d<\/p>\n

Because of this, Dani says, excitons \u201ccan thus achieve strong Floquet effects while avoiding the challenges posed by light.\u201d The team says this offers a novel means of exploring various applications, which include \u201cexotic future quantum devices and materials that Floquet engineering promises.\u201d<\/p>\n

Such unique phenomena could enable material science<\/a> applications that are almost akin to alchemy, in that the concept of creating new materials simply by shining light on them sounds more like science fiction<\/a> than even the most advanced 21st-century engineering.<\/p>\n

Floquet Engineering<\/strong><\/p>\n

In the past, Floquet effects have remained elusive in the lab, although investigations over the years have demonstrated their promise, provided they can be achieved under practical conditions. However, a major limiting factor has been reliance on intense light as the primary driving force, which can also lead to damage or even vaporization of the materials, thereby limiting useful results.<\/p>\n

Normally, Floquet engineering focuses on achieving such effects under quantum conditions that challenge our usual expectations of time and space. When researchers employ semiconductors or similar crystalline materials as a medium, electrons behave in accordance with what one of these dimensions\u2014space\u2014will allow. This is because of the distribution of atoms, which confines electron movement and thereby limits their energy levels.<\/p>\n

Such conditions represent just one \u201cperiodic\u201d condition that electrons are subjected to. However, if a powerful light is shone on the crystal at a certain frequency, it represents an additional periodic drive, albeit now in the dimension of time. The resulting rhythmic interaction between light (i.e., photons) and electrons leads to additional changes in their energy.<\/p>\n

By controlling the frequency and intensity of the light used as this secondary periodic force, electrons can be made to exhibit unique behaviors, which also cause changes in the material they inhabit for the time during which they remain excited.<\/p>\n

From Light to Excitons<\/strong><\/p>\n

\u201cUntil now, Floquet engineering has been synonymous with light drives,\u201d according to Xing Zhu, who is currently a PhD student at OIST. However, because light couples poorly with matter, researchers have been limited in the past to achieving such effects mostly at the femtosecond scale.<\/p>\n

\u201cSuch high energy levels tend to vaporize the material,\u201d Zhu says, adding that \u201cthe effects are very short-lived.\u201d<\/p>\n

\u201cBy contrast, excitonic Floquet engineering require much lower intensities,\u201d Zhu says.<\/p>\n

According to Professor Gianluca Stefanucci of the University of Rome Tor Vergata, one of the recent study\u2019s co-authors, excitons are an ideal alternative to photons because they carry self-oscillating energy that can affect the surrounding material at frequencies that can be controlled through proper tuning.<\/p>\n

\u201cBecause the excitons are created from the electrons of the material itself, they couple much more strongly with the material than light,\u201d Stefanucci said.<\/p>\n

\u201cAnd crucially, it takes significantly less light to create a population of excitons dense enough to serve as an effective periodic drive for hybridization\u2014which is what we have now observed,\u201d he adds.<\/p>\n

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In the past, the OIST team has conducted exciton research using a specially designed setup called TR-ARPES, which stands for \u201ctime- and angle-resolved photoemission spectroscopy.\u201d During experiments, the team excited a very thin, atomic-thickness semiconducting material with light, while recording the energy levels of the electrons within. This allowed the team to observe the manifestation of Floquet effects and, in addition, to measure electron signals at the femtosecond scale.<\/p>\n

Significantly, this enabled the researchers to independently gauge Floquet effects associated with optical phenomena from those related to excitonic behavior.<\/p>\n

\u201cIt took us tens of hours of data acquisition to observe Floquet replicas with light,\u201d said Dr. Vivek Pareek, a Presidential Postdoctoral Fellow at the California Institute of Technology. Despite the amount of data required, the team was able to achieve excitonic Floquet effects, he confirms, \u201cand with a much stronger effect.\u201d<\/p>\n

The team says their results prove that Floquet effects can be achieved under such conditions and that they can be reliably generated using a more formidable means (excitons, in this case) than light alone can provide. This opens the door to the potential use of such capabilities across a range of applications that could aid the development of useful quantum materials and devices.<\/p>\n

Dr. David Bacon, the recent study\u2019s co-first author, says he and his colleagues have \u201copened the gates to applied Floquet physics,\u201d an achievement that is \u201cvery exciting, given its strong potential for creating and directly manipulating quantum materials.\u201d<\/p>\n

\u201cWe don\u2019t have the recipe for this just yet,\u201d Bacon added, though adding that \u201cwe now have the spectral signature necessary for the first, practical steps.\u201d<\/p>\n

The team\u2019s research was recently detailed in the study, \u201cDriving Floquet physics with excitonic fields,<\/a>\u201d
published in Nature Physics.<\/p>\n

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at<\/strong>\u00a0<\/strong>micah@thedebrief.org<\/strong><\/a>. Follow him on X\u00a0<\/strong>@MicahHanks<\/strong><\/a>, and at\u00a0<\/strong>micahhanks.com<\/strong><\/a>.<\/strong><\/p>\n

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