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Alumni - Doctoral projects
© Joannis Koepsell

Fermi­onic Quantum Gas Microscope

Joannis Koepsell – Hector Fellow Immanuel Bloch

The micro­scopic descrip­tion of a multi­tude of exotic phenom­ena such as magnet­ism or high-temper­a­ture super­con­duc­tiv­ity still raises questions. This project deals with the simula­tion of these phenom­ena using a quantum gas micro­scope. In this project, ultra­cold fermi­onic lithium atoms are made to behave identi­cally to electrons in a solid state by controlled optical light fields. By using a high-resolu­tion fluores­cence image, the behav­iour of each individ­ual atom can be observed.

A rich variety of phenom­ena in solid state systems such as quantum magnet­ism or high temper­a­ture super­con­duc­tiv­ity still pose open questions on parts of their micro­scopic expla­na­tion. Due to the complex­ity of these systems, the under­ly­ing quantum many-body dynam­ics is often not acces­si­ble to compu­ta­tional simula­tion. Fermi­onic Quantum Gas Micro­scopes resolve the spin and density of single lattice sites in quantum gas exper­i­ments and repre­sent an novel platform to simulate condensed matter phenom­ena. In these exper­i­ments, atoms cooled to the quantum regime are manip­u­lated by light fields to gener­ate optical lattices and finally mimic solid state systems in which the inter­act­ing fermi­onic atoms replace the electrons.

This project is carried out in the Lithium Quantum Gas Micro­scope exper­i­ment of Hector Fellow Immanuel Bloch. It aims at moving towards quantum simula­tion of the Fermi Hubbard model, topolog­i­cal edge states in super­lat­tices and the Fulde-Ferrell-Larkin-Ovchin­nikov phase in spin imbal­anced systems. Our setup has the unique feature to simul­ta­ne­ously resolve spins, doubly occupied sites and holes at the same time. Recently, one of the first single site resolved images of fermi­onic atoms in optical lattices was realized. A new super­lat­tice gener­a­tion will be imple­mented to reach lower entropies, increase the system size and to reach higher energy scales.

RR Lyrae stars as tracers of substructure and Galactic archaeology

Single site resolved image of Lithium atoms in an optical lattice shown with an artis­tic view of the microscope

Joannis Koepsell

Ludwig Maxim­il­ian Univer­sity of Munich

Super­vised by

Prof. Dr.

Immanuel Bloch


Hector Fellow since 2012