Quantum Electronics in Silicon and Diamond
Scientists from the team of Associate Professor Martin Kozák at the Department of Chemical Physics and Optics, CUNI, have developed an optical method that allows information to be encoded and read in pure crystals of silicon and diamond within an extremely short period of time. The research results were published in the journal Nature Physics.
Current electronics is largely based on silicon chips, where information is transmitted and processed in the form of electric charge carried by electrons conducting electric current. Recently, however, a new idea has emerged: to utilize not only the charge of electrons but also their quantum state, determined by the energy minimum (or valley) in the conduction band in which they reside.
Martin Kozák’s team has developed an optical method that enables the encoding and reading of information in pure crystals of silicon and diamond by manipulating the population of electrons within individual valleys.
“Quantum theory tells us that microscopic particles can behave like waves. Our new method is based on manipulating the quantum state of electrons in crystals using infrared light in the form of short pulses. It turns out that if we oscillate the electrons with the electric field of the pulse in a certain direction, they rearrange in what's known as reciprocal space, and we are able to control the direction of their wave vector, which can then be used as a bit of information,” explains Associate Professor Kozák.
The method enables manipulation of the quantum state of electrons in silicon and diamond crystals using illumination with infrared light
Silicon is the most important semiconductor in the technology industry, used in everything from computer microprocessors to solar cells. Despite decades of research, it had not been possible until now to harness the quantum state of electrons in silicon, because there was no effective way to control or detect it. This is exactly what the new method, developed by Associate Professor Kozák's team, now enables. Moreover, the method can switch the state of electrons within just tens of femtoseconds and at room temperature.
The study is part of the eWaveShaper project, for which Associate Professor Kozák received the prestigious ERC Starting Grant in 2022. The goal of this research is to develop new methods for ultrafast control and imaging of electron motion in solids using light and pulsed electron beams.
“Unfortunately, electrons don’t remain in a state with a specific wave vector for very long. Our current goal is to identify materials and conditions under which the so-called valley polarization of electrons lasts as long as possible, so that this state can be used for information transfer and processing,” outlines Associate Professor Kozák the direction of future research.
Link to the
study:
Gindl, A., Čmel, M., Trojánek, F. et al. Ultrafast room-temperature valley manipulation in silicon and diamond. Nat. Phys. (2025). DOI: https://doi.org/10.1038/s41567-025-02862-4
OPMK, cover photo by Hynek Glos
