Low energy excitations in bosonic quantum quasicrystals

by Alejandro Mendoza

Monday 9 Dec 2024, 14:30 → 15:30 Europe/Rome

324 (Dipartimento di Fisica )

In this work we present the first principles construction of the
low-energy effective action for bosonic self-organized quantum quasicrystals. Our generalized elasticity approach retains the appropriate number of phase- and corresponding conjugate density degrees-of freedom
required for a proper description of the Goldstone modes of the system. For the dodecagonal and decagonal quasicrystal structures we obtain
collective longitudinal and transverse excitations with an isotropic
speed of sound. Meanwhile, for the octagonal structure, the coupling between phononic and phasonic
degrees of freedom leads in
turn to hybridization of the latter with the condensate sound mode,
producing collective excitations with a longitudinal and transverse component, and an anisotropic
speed of sound. Finally, we discuss the fate of each excitation mode at the low and high density phase transitions limiting the
quantum quasicrystal phase.