TRR 185:  OSCAR - Open System Control of Atomic and Photonic Matter

• Subject Area: Physics
• Term: since 2016
• Website: Homepage
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 277625399

A common presumption in quantum physics is that for systems to be dominated by quantum effects they must be isolated from influences of the environment as good as possible. This isolation is considered to be a key requirement for many quantum technologies. The central paradigm of the CRC/TR 185 is the opposite approach. We consider the coupling to reservoirs as potentially useful tools rather than an unavoidable nuisance. The vision is to utilize external drive and properly tailored reservoirs to counteract the effects of generic, uncontrolled environments and to create a toolbox of open system control for few- and many-body quantum systems. This comprises the generation, control and stabilization of interesting and useful quantum states as well as the stimulation and manipulation of collective processes. It also includes the exploration of the interface between the field of topological systems with open system control. We aim to understand the underlying mechanisms of open systems and to exploit them as new tools going far beyond what is possible in closed systems. The research field of open-system control of quantum matter is a very recent one. During the first funding period the CRC/TR 185 has taken a key role in shaping this field. The experimental platforms underlying our research are atoms and photons, for which the technology of manipulation and detection are most advanced and a microscopic control as well as a detailed understanding of system and environment is possible. The systems reach from driven photon condensates over single atoms, which are coupled to quantum light, to ultracold atomic quantum gases. The research program is structured in three complementary areas. Research area A 'Few-body quantum systems and environments' follows a bottum up approach and explores the influence of tailored environments on individual or few-body quantum systems. Therefore, the experimental platforms are chosen with a maximum degree of control. Research area B 'Control of quantum many-body systems by environments' focuses on the generation, control and manipulation of collective states or processes of complex many-body systems. Due to the complexity of the system, typically not all degrees of freedom can be controlled and measured and the theoretical treatment is very challenging. Research area C 'Topological states in atomic and photonic systems' interfaces the directions of open-system control and topological protection, where the goal is to devise a general approach to protect quantum states by combining these two areas.

• DFG Programme: CRC/Transregios

Current projects

• A02 - Remote entanglement by environment control in optical cavity arrays (Project Heads Köhl, Michael ;  Meyer, Hendrik-Marten )
• A04 - Dynamical bath control with localized impurities in a quantum gas (Project Heads Schneider, Imke ;  Widera, Artur )
• A05 - Time-periodic driving: Floquet engineering beyond the high-frequency approximation (Project Head Eggert, Sebastian )
• A06 - Open-System Control of Dynamical Transitions (Project Head Anglin, James )
• A07 - Precision control of a single impurity in a fermionic bath (Project Head Stellmer, Simon )
• A08 - Strongly correlated few-body states of Rydberg polaritons (Project Head Hofferberth, Sebastian )
• B01 - Dynamics of an open photon Bose-Einstein condensate system (Project Heads Kroha, Johann ;  Schmitt, Julian ;  Vewinger, Frank ;  Weitz, Martin )
• B02 - Dissipative dynamics of strongly interacting, optically driven Rydberg gases (Project Heads Fleischhauer, Michael ;  Niederprüm, Thomas ;  Ott, Herwig )
• B03 - Ultracold quantum gases in spatially and temporally engineered environments (Project Heads Kollath, Corinna ;  Ott, Herwig )
• B04 - Dynamical and dissipative control of ultracold atomic Fermi gases (Project Heads Kollath, Corinna ;  Köhl, Michael ;  Sheikhan, Ameneh )
• B05 - The BEC-BCS crossover in a gas with controlled disorder (Project Head Widera, Artur )
• B06 - Dimensional crossover in trapped photon gases (Project Heads von Freymann, Georg ;  Pelster, Axel ;  Vewinger, Frank )
• C01 - Topological phases in open systems (Project Head Fleischhauer, Michael )
• C04 - Periodically driven many-body and dissipative systems: Topological stabilization of transport (Project Heads Kroha, Johann ;  Linden, Stefan )
• C05 - Gauge fields and topological states with cold atoms (Project Head Weitz, Martin )
• C06 - Topological lattice models at finite temperature (Project Heads Fleischhauer, Michael ;  Köhl, Michael ;  Ott, Herwig )
• MGK - Integrated Research Training Program i-OSCAR (Project Heads Fleischhauer, Michael ;  Linden, Stefan )
• Z - Administration of OSCAR (Project Heads Fleischhauer, Michael ;  Meschede, Dieter )

Completed projects

• A01 - Controlled few-particle quantum states in an optical cavity QED system (Project Heads Meschede, Dieter ;  Ratschbacher, Lothar )
• A03 - Plasmon mediated interaction of quantum emitters (Project Head Linden, Stefan )
• C02 - Topological phases in discrete-time quantum walks (Project Heads Alberti, Ph.D., Andrea ;  Meschede, Dieter )

• Applicant Institution: Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau
• Co-Applicant Institution: Rheinische Friedrich-Wilhelms-Universität Bonn
• Spokespersons: Professor Dr. Michael Fleischhauer, since 7/2020; Professor Dr. Dieter Meschede, until 6/2020