Laser System for Quantum Gas Microscopy of Topological Many-Body States with Cs Atoms

• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: Funded in 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 452143229

In the planned project, the concepts of quantum gas microscopy and artificial gauge fields in systems based on ultracold atoms will be combined in a new experiment. This will realize completely new systems that will allow probing of interacting topological many-body systems with a host of new and innovative diagnostic tools (e.g. single atom and spin resolution, local current operator measurements between lattice sites, etc.). At the same time, new ideas for the realization of artificial gauge fields will allow the individual control of tunnel matrix elements between lattice sites. Most of the fundamental concepts for this project have been demonstrated by the group of the applicant, but it has not yet been possible to combine them in a single experiment and thus benefit from both of these innovative concepts. This proposal aims at overcoming these imitations based on a new experimental setup and the laser system applied for in this proposal.The complete system consists of four units: 1) In order to achieve fast cycle times for quantum simulations, a fast and reliable transport will be realized by means of a moving optical standing wave. For this purpose, low-noise high-power lasers at 1064nm will be used, which can also be employed for an optical dipole trap. Fast cycle times are indispensable, especially when higher order correlation functions and many-body entanglement are to be measured, which place considerable demands on data acquisition in the system. At the same time, short cycle times of the experiments also allow a significant reduction of unwanted drifts and fluctuations in the experiment and thus a much more stable data acquisition. 2) The experimental scheme for the local control of the tunnel couplings and the generation of artificial calibration fields is based on a special state-dependent lattice potential in the horizontal plane, which will later also be used as a lattice for the single-site resolved imaging. To achieve the required lattice depths and lattice configurations, Ti:Sapphire laser systems with tunability between 760-900 nm will be used. 3) In order to obtain maximum information about the density and internal spin state distribution of the cold bosons in the lattice, a vertical superlattice at 1064nm and 532nm will be employed, which allows to image both spin and density by topological spin pumping in a single experimental realization. 4) To control the frequency of and monitor the intensity fluctuations of the lasers, a linewidth analyzer with good absolute accuracy is needed.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Lasersystem zur Quantengasmikroskopie für Cs Atome, rauscharme Hochleistungslaser und Diagnostik
• Instrumentation Group: 5700 Festkörper-Laser
• Applicant Institution: Ludwig-Maximilians-Universität München
• Leader: Professor Dr. Immanuel Bloch