Speaker
Description
We will discuss our recent results on how quantum geometry affects various physical observables. For flat bands, we show that superfluidity [1,2] as well as stability of a Bose-Einstein condensate [3] is solely given by quantum geometric effects, such as finite quantum metric (Fubini-Study metric). Examples of prominent flat band systems are the Lieb lattice, the saw-tooth ladder, and moire materials. We find that, strikingly, quasiparticles do not move in flat band superconductors/superfluids even under non-equilibrium conditions [4], which can be important for quantum devices. Finally, we show that superfluidity and transport of interacting bosons in a one-dimensional flat band systems is governed by the many-body quantum metric [5], showing that also the many-body version of the quantum metric can have physical significance. We discuss various ultracold gas systems where these new quantum geometry effects could be observed.
[1] S. Peotta, P. Törmä, Nature Commun. 6, 8944 (2015); K.-E. Huhtinen, J. Herzog-Arbeitman, A. Chew, B.A. Bernevig, P. Törmä, Phys. Rev. B 106 , 014518 (2022)
[2] P. Törmä, S. Peotta, B.A. Bernevig, Nat. Rev. Phys. 4, 528 (2022)
[3] A. Julku, G.M. Bruun, P. Törmä, Phys. Rev. Lett., 127, 170404 (2021), ibid Phys. Rev. B 104, 144507 (2021)
[4] V.A.J. Pyykkönen, S. Peotta, P. Törmä, Phys. Rev. Lett. 130, 216003 (2023); V.A.J. Pyykkönen, S. Peotta, P. Fabritius, J. Mohan, T. Esslinger, P. Törmä, Phys. Rev. B 103, 44519 (2021)
[5] G. Salerno, T. Ozawa, P. Törmä, in preparation (2023)
