Dr. Imke Schneider

Department of Physics
RPTU Kaiserslautern-Landau
Erwin Schrödinger Straße
67663 Kaiserslautern, Germany

Office: Building 46, room 556
Phone: +49 631 205 2893
E-Mail: ischneider[at]physik.uni-kl[dot]de

Research Interest

My general area of research is theoretical quantum many-body physics. My specific interest is in strongly correlated materials where physical properties are dominated by interaction effects. These materials exhibit a number of intriguing collective phenomena of which superconductivity is the most prominent example. Strongly correlated matter has already found manifold technological applications. Yet, both realizing and understanding the collective elementary excitations and their dynamics remain major scientific challenges.
A possible route to understanding strong interaction effects is to study systems in low dimensions. Indeed, various notable features of strongly correlated electronic materials, such as high-temperature superconductivity in the cuprates, and the quantum Hall effect occur in systems where the effective spatial dimension is less than three. In one spatial dimension correlation effects are particularly strong, leading to qualitatively new physical features. To give one example the Fermi liquid paradigm of electron-like quasi-particles is known to break down in one dimension. Strong correlations lead to the remarkable fractionalization, in which the fundamental excitations of the low-energy many-electron state consist of separate spin and charge density waves.
Most of my research so far has focused on one-dimensional systems with a particular focus on effects of impurities and boundaries on dynamical response functions. The breaking of translational invariance causes local variations in the vicinity of the impurity from which characteristic properties of the bulk state of matter can be inferred. In a series of works I have studied such scattering effects on the local density of states and the dynamical structure factor by using a combination of analytical bosonization techniques and numerical DMRG methods.
A current research direction is to understand dynamical processes in systems that are out of equilibrium. The enormous progress in simulating condensed matter systems by ultracold gases on optical lattices has made it possible to experimentally address fundamental questions about non-equilibrium physics in isolated quantum many-body systems. I consider experimentally measurable observables and work on their real-time dynamics after the system is locally set out of equilibrium.
As well as one-dimensional systems, my research also addresses more general aspects of strongly correlated systems. For example, I am interested in quantum phase transitions and quantum criticality. Quantum phase transitions occur at zero temperature driven by quantum fluctuations as opposed to classical finite temperature phase transitions. Continuous (second order) quantum phase transitions are controlled by a quantum critical point. In the vicinity of this phase transition very unusual behaviour can be found and novel phases may be discovered. The quantum critical regime emerges in a wide temperature range making the exotic behaviour experimentally accessible. My specific interest is in nontrivial fixed points and associated phase transitions in quantum impurity problems with applications, e.g., for impurities in correlated electronic environments, quantum dot systems, and for strongly correlated lattice models where effective impurity models appear in dynamical mean-field approximations.