Welcome Nicolas Ubrig
Please meet Nicolas Ubrig, new Assistant Professor at POLIMA
What is your background?
I am an experimental physicist whose research lies at the intersection of optical spectroscopy and quantum transport.
What is your research interests?
I am interested in the electronic properties of matter and how we can control these properties. The class of materials in which this is possible is atomically thin two-dimensional materials. These materials—just a single atom thick—continue to surprise and inspire. Just when you think the story is over, they reveal something new. Now we are able to take two distinct crystals, each with the thickness of a single atom, and stack them. If we introduce an angle between these two layers, we create a new material with a myriad of novel properties.
I discovered and learned to work with these materials during my PhD at the High Field Magnet Laboratory in Toulouse and later as a researcher at the University of Geneva. There, we uncovered fascinating new phenomena related to optical excitations in these materials. After laser excitation, semiconductors like the ones we studied form quasiparticles known as excitons. These are essentially pairs of oppositely charged carriers—electrons and their counterparts, which we call holes. We demonstrated that in these 2D semiconductors, optical excitations can replace a magnetic field in influencing the motion of charge carriers—an effect known as the valley Hall effect. We also created excitons at semiconducting interfaces, where electrons and holes reside in different layers, giving these excitons significantly longer lifetimes than those in the individual materials.
Now we can begin to combine these effects and start controlling the particles in solids to create what we call phases. These are states—like solid and liquid—but more complex, as the system's properties are dominated by correlations between excitons and electrons within the material. Through optical and electrical experiments, we aim to control these phases and investigate their quantum mechanical properties.
Why did you choose to join POLIMA?
The position at the DNRF Centre POLIMA is ideal as it offers a dynamic environment where theorists and experimentalists using complementary techniques collaborate to explore these materials at the nanometer scale. One of the key challenges is observing individual excitons, which is not possible with conventional optical microscopes or standard optical detection techniques.
I am an experimental physicist whose research lies at the intersection of optical spectroscopy and quantum transport.
What is your research interests?
I am interested in the electronic properties of matter and how we can control these properties. The class of materials in which this is possible is atomically thin two-dimensional materials. These materials—just a single atom thick—continue to surprise and inspire. Just when you think the story is over, they reveal something new. Now we are able to take two distinct crystals, each with the thickness of a single atom, and stack them. If we introduce an angle between these two layers, we create a new material with a myriad of novel properties.
I discovered and learned to work with these materials during my PhD at the High Field Magnet Laboratory in Toulouse and later as a researcher at the University of Geneva. There, we uncovered fascinating new phenomena related to optical excitations in these materials. After laser excitation, semiconductors like the ones we studied form quasiparticles known as excitons. These are essentially pairs of oppositely charged carriers—electrons and their counterparts, which we call holes. We demonstrated that in these 2D semiconductors, optical excitations can replace a magnetic field in influencing the motion of charge carriers—an effect known as the valley Hall effect. We also created excitons at semiconducting interfaces, where electrons and holes reside in different layers, giving these excitons significantly longer lifetimes than those in the individual materials.
Now we can begin to combine these effects and start controlling the particles in solids to create what we call phases. These are states—like solid and liquid—but more complex, as the system's properties are dominated by correlations between excitons and electrons within the material. Through optical and electrical experiments, we aim to control these phases and investigate their quantum mechanical properties.
Why did you choose to join POLIMA?
The position at the DNRF Centre POLIMA is ideal as it offers a dynamic environment where theorists and experimentalists using complementary techniques collaborate to explore these materials at the nanometer scale. One of the key challenges is observing individual excitons, which is not possible with conventional optical microscopes or standard optical detection techniques.
