Research

Strongly correlated quantum systems

Strong interactions in quantum systems can trigger exotic phenomena that are not described by perturbation theory of a non-interacting model. A precise description of the states and dynamics of these correlated quantum systems often invokes advanced theoretical or numerical methods, such as quantum field theory, tensor-network-based algorithms, or quantum Monte Carlo simulations. Using such tools, we study strongly correlated systems, e.g., the Wigner crystal of electrons in a carbon nanotube (see figure and the reference below), and non-equilibrium dynamics of one-dimensional quantum magnets.
 

Figure reference: I. Shapir, A. Hamo, S. Pecker, C. P. Moca, Ö. Legeza, G. Zaránd, S. Ilani,  Science 364,  870-875 (2019).

Topology in quantum physics

Topology is an efficient toolkit that enhances our understanding of condensed matter and quantum information. One topology-related research direction in our group is the study of quantum systems where the interplay of disorder, time-dependent control and topology leads to unexpected features. Furthermore, topological properties of certain condensed-matter systems are planned to be exploited to do quantum computing in a noise-resistant fashion, often referred to as topological quantum computing. We evaluate the potential in condensed-matter systems that could be used toward this goal, by studying the physical principles of quantum control, qubit readout, and the correction of errors. 

 

Figure reference: János K. Asbóth, László Oroszlány, András Pályi, "A Short Course on Topological Insulators",  (Springer Verlag, Berlin, 2016).

Physics of quantum computing

We theoretically study the physical principles of quantum computing in condensed-matter systems: electron and nuclear spins in semiconductors (see figure), and superconducting nanodevices. How to control these qubits with magnetic or electric fields, as efficiently as possible? How does the environment - electric noise, phonons, photons - lead to qubit decoherence, and how to protect the qubit against that? What are mechanisms that allow for qubit readout, why is readout imperfect, and how to make it perfect? How to organize an architecture where multiple physical qubits form a single logical qubit, as required for quantum error correction?

 

Figure reference: Bence Hetényi, Péter Boross, András Pályi, Phys. Rev. B 100, 115435 (2019).