Hochauflösende Quantengas-Mikroskopie von ultrakalten 23Na40K Molekülen in optischen Gittern
Zusammenfassung der Projektergebnisse
The goal of this research project was to build a novel multipurpose quantum hardware based on ultracold dipolar 23Na40K molecules trapped in an optical lattice. Ultracold molecules represent a radically new platform which borrows the techniques and scalability from ultracold atoms and combines it with the tunable long-range interactions of dipolar molecules. At MIT, we investigated one of the archetypal quasiparticles: the Bose polaron. This quasiparticle arises from the interaction between an impurity and a phonon bath. We probed for the first time strongly-coupled Bose polarons – in our case fermionic 40K impurities dressed by a 23Na Bose- Einstein condensate – in local thermal equilibrium as they approach quantum criticality. Our findings demonstrate that strongly interacting Bose-Fermi mixtures near a quantum critical point attain the same universal character as the strange metal phase of cuprate superconductors, where the resistivity is found to scale linearly with temperature. Our study of the Bose polaron quasiparticle revealed that the polaron’s wavefunction is sufficiently molecule like that it theoretically could allow for a coherent conversion of Bose polarons into ground state molecules without relying on Feshbach association. This many-body assisted pathway of creating ground state molecules represents a new paradigm for creating ultracold dipolar molecules as such an approach could overcome the shortcomings of magneto or RF association of free atoms into Feshbach molecules which is conventionally the first step in creating ultracold ground state molecules. I have confirmed the molecule-like character of Bose polaron quasiparticles by utilizing photo association spectroscopy to directly measure the coupling strengths to highly excited molecular states. My measurements reveal coupling strengths which are comparable to Feshbach molecules. These findings allowed me recently to create for the first-time ground state NaK molecules directly from Bose polarons using a two photon STIRAP pathway. This approach has a significantly enhanced conversion efficiency, which opens the path to creation of a degenerate gas of ultracold molecules without additional evaporative cooling. To deepen our understanding of the rich many-body phase diagram and dynamics of the Bose-Fermi mixture in the impurity limit I have additionally observed the dissipationless flow of fermionic 40K atoms immersed in a BEC of 23Na atoms and observed the fermion impurities emitting Bogoliubov-Cherenkov radiation when the relative velocity between the impurities and the BEC exceeds the BEC’s speed of sound.
Projektbezogene Publikationen (Auswahl)
- Demonstration of quantum brachistochrones between distant states of an atom, Phys. Rev. X 11, 011035 (2021)
M. R. Lam, N. Peter, T. Groh, W. Alt, C. Robens, D. Meschede, A. Negretti, S. Montangero, T. Calarco and A. Alberti
(Siehe online unter https://doi.org/10.1103/PhysRevX.11.011035) - Mosaic and non-mosaic pcdh19 mutation leads to neuronal hyperexcitability in zebrafish. Neurobiology of Disease
B. K. Robens, X. Yang, C. M. McGraw, L. H. Turner, C. Robens, S. Thyme, A. Rotenberg, A. Poduri
(Siehe online unter https://dx.doi.org/10.1016/j.nbd.2022.105738)
