The new assistant professor at ISTA combines ultrafast physics with quantum mechanics

The Institute of Science and Technology Austria (ISTA) has appointed a new assistant professor Denitsa Bykusheva, who specializes in ultrafast laser spectroscopy. By developing technology to study the interaction between light and matter from the perspective of quantum physics, Pykusheva seeks to bridge the gap between high-speed physics and quantum mechanics. This linking of disciplines could lead to the development of new materials and ultrafast electronics.

As one of the newest assistant professors at the Institute of Science and Technology of Austria (ISTA), Denitsa Bykusheva talks about her ideas and plans over coffee on a busy Friday morning. In fulfillment of ISTA's interdisciplinary mission, it conducts research between physics, physical chemistry and materials science. During her PhD at ETH Zurich and her research residencies at the Stanford PULSE Institute for Ultrafast Energy Sciences and Harvard University, she specialized in studying the interaction between light and matter mediated by intense and ultrashort laser fields. “My research group is at ISTA “It aims to bring the fields of ultrafast physics and quantum mechanics closer together,” says Bykusheva.

Light and matter: quantum mechanics on both sides of the interaction

Often referred to as the “glue of matter,” electrons are actually quantum entities at the microscopic level. In some solids, the quantum properties of electrons exceed the small scales of the quantum world. On a large scale, they lead to interesting collective behaviors, such as superconductivity or quantum magnetism. Such materials, known for their strong electronic correlations, are often referred to as “quantum materials.” Their exotic physical properties make quantum materials particularly useful for research, but also for electronics, photonics, energy storage and information technology.

In the last century, physicists have mostly used external stimuli such as pressure or electric and magnetic fields to create and change new states of matter. “In recent years, ultrashort laser fields have made it possible to discover new properties of quantum materials by stabilizing transient nonequilibrium states of matter,” says Bykusheva. However, until now, ultrafast interactions between light and matter have not been fully studied from the perspective of quantum physics. Instead, the principles of quantum mechanics were applied to only one aspect of the interaction – the matter part – while light was still viewed as a classical electromagnetic field. This perspective is therefore called “semi-classical”.

New materials for ultrafast electronics

The semiclassical perspective focuses primarily on the average intensity of light. However, the number of photons can exhibit characteristic fluctuations, even in a vacuum, explains Bykusheva. By analyzing light fluctuations during interactions between light and matter, she wanted to learn more about intrinsic fluctuations in the properties of materials. This information is essential for understanding thermal and quantum phase transitions in materials. “How the strong correlations between electrons in systems such as superconductors affect the quantum properties of light – and vice versa – remains largely unexplored,” Baykusheva adds.

Baykusheva's work will help develop new materials with new properties: “The overarching goal of my research team is to fully integrate ultrafast spectroscopy into the field of quantum physics. By better understanding this gap, we gain deeper insight into the macroscopic structured stages of learning and can thus create new stages of Subject.” In addition, the research of Baykusheva's group can further advance the development of ultrafast electronics, one of the most promising technologies of the digital future.

High-tech laser

To achieve her goals, Baykusheva is currently equipping two dedicated laboratory spaces with advanced technologies to study two complementary aspects of her research: temporal resolution and spatial resolution. “For our work as an experimental research group, which is based on small measurements using ultrafast optics, stable environmental conditions such as temperature and humidity must be ensured,” says Baykusheva. This is necessary to control matter on very short time scales and over small distances. “One of our laboratories will be equipped with a laser system that emits photons at 800 nanometers, on the border between visible and near-infrared light,” explains Baykusheva.

“However, to study the collective excitation that underlies the complex behaviors of matter at the macro level, we need to upconvert the light pulses into the mid-infrared region to the terahertz region of the spectrum. At these frequencies, laser beams are invisible to the naked eye. That is why” we will build “Our own devices generate and detect these frequencies and manipulate their photon states.” This technology will allow Bykusheva to disturb materials and then investigate their atomic and subatomic properties on their natural time scales. “The ultimate goal is to explore states of matter that cannot be achieved under equilibrium conditions.”

These experiments study the properties of matter on a scale of tens to hundreds of micrometres, which is comparable to the size of a typical fog droplet. However, such an optical focal point is too large to be able to study local quantum properties with high spatial resolution. “In the second laboratory space, we will develop tools to overcome the diffraction limit and study long-range quantum properties in solid materials, including quantum entanglement, directly in real space,” explains Bykusheva.

Research the limits of what is possible

The opportunity to conduct independent research at the intersection of several disciplines brought the Bulgarian-born woman to ISTA. “The level of independence and technical support I receive at ISTA, as well as the representation of quantum physics in the campus community, is such that there are very few places like ISTA,” she says. “Quite apart from the 2022 Nobel Prize in Physics, which was awarded to quantum physicist Anton Zeilinger, there is a lively quantum community in Austria, from ISTA to various universities.” In addition to establishing research cooperation in Austria, Baykusheva is currently focusing on building a team. “I hope that the students and postdocs will be highly motivated and willing to take risks and do very challenging research within the limits of what is possible.”

Medienkontakt:
Andreas Rothe
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