Regensburg 2025 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 20: Many-body Quantum Dynamics II (joint session DY/TT)

DY 20.8: Talk

Wednesday, March 19, 2025, 11:30–11:45, H37

Chiral basis for qubits and decay of spin-helix states — •Frank Göhmann — Fakultät für Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, 42097 Wuppertal, Germany

In a recent cold-atom experiment by the Ketterle group at MIT one-dimensional spin-helix states could be prepared and their time evolution induced by the XXZ Hamiltonian could be observed. The experiment allows to adjust the anisotropy parameter of the latter. For the special case of the XX model we describe the spatio-temporal decay of a transversal spin helix explicitly. The helix pattern stays stable in space, but has a non-trivial time-dependent decay amplitude which is of scaling form and is governed by a universal function that can be represented as a semi-infinite determinant related to the discrete Bessel kernel. This representation is valid for all times, is numerically utterly efficient and allows us to obtain the long-time asymptotics of the function. Our work is a rare example of a quench that has been experimentally realized and for which the full time dependence could be calculated exactly.

V. Popkov, X. Zhang, F. Göhmann and A. Klümper, Chiral basis for qubits and spin helix decay, Phys. Rev. Lett. 132 (2024) 220404 (5pp)

Keywords: quench; dynamics of quantum spin chain; cold atom experiment; exact result for one-point correlation function