Project Details
Projekt
T2 Ultracold atoms as quantum simulators for open systems
Applicant
Professor Dr. André Eckardt
Subject Area
Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 521530974
Ultracold atoms are highly tunable and clean engineered quantum systems. They permit to experimentally study interesting many- and few-body states of matter in and out of equilibrium. A rather unique feature is their exceptional high degree of isolation from the environment. In this project, we will investigate, how this absence of uncontrolled dissipation can actually be exploited to engineer systems with fully controlled dissipation. In close collaboration with the other experimental and theoretical projects of the Research Unit, we will explore and extend the capability of atomic quantum gases to serve as quantum simulators for open many-body systems. Beyond ultra-weak system-bath coupling and away from equilibrium, the state of the system will depend on the details of the environment (and not only on its temperature, chemical potential etc.). Therefore, an accurate theoretical description of the open system is crucial. We plan to microscopically derive master/stochastic equations of motion for open quantum-gas systems with engineered fully characterized reservoirs, using different standard and advanced approaches (like, inter alia, Born-Markov theory or our canonically consistent quantum master equation). By comparing their predictions for three relevant scenarios (strong system-bath coupling, non-equilibrium steady states of an open driven system, and transient relaxation dynamics) to experiments in Hamburg and Munich, we will benchmark them and explore their range of validity. We will also design and investigate strategies of reservoir engineering for in-situ cooling optical lattice systems. Our focus will lie on bosonic Mott-insulator states, but in principle the methods to be developed will generalize to the preparation of other gapped many-body states, like fractional Chern insulators. Using standard techniques it is already possible to prepare a Mott insulator, contaminated by a small fraction of thermal particle-hole excitations only. To remove also these, we will design (an array of) one-way reservoirs, each of which is capable of removing one excitation via an energy-selective golden-rule type transition in the system. We will closely collaborate with the Munich team, who will work on the implementation. Finally, we plan to design a scheme for a proof-of-principle experiment demonstrating quantum feedback control in the cavity experiment in Zurich. Heterodyn detection of photons scattered by the atoms from a structured probe beam into a cavity mode shall be combined with measurement conditioned forcing via light-shift potentials. In particular, we will aim for the control of non-equilibrium Bose condensates, where we anticipate that the expected measurement efficiencies of about 10 percent only can be compensated by increased boson densities.
DFG Programme
Research Units
Co-Investigator
Dr. Alexander Schnell
