TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhysCore.6.1.003
TI  - Nonlocal field theory of quasiparticle scattering in dipolar Bose-Einstein condensates
PY  - 2023/01/23
UR  - https://scipost.org/SciPostPhysCore.6.1.003
JF  - SciPost Physics Core
JA  - SciPost Phys. Core
VL  - 6
IS  - 1
SP  - 003
A1  - Holanda Ribeiro, Caio C.
AU  - Fischer, Uwe R.
AB  - We consider the propagation of quasiparticle excitations in a dipolar Bose-Einstein condensate, 
and derive a nonlocal field theory of quasiparticle scattering 
at a stepwise inhomogeneity of the sound speed, obtained by tuning the contact coupling part of the interaction on one side of the barrier.  
To solve this problem ab initio, i.e., without prior assumptions on the form of the solutions, we reformulate the dipolar Bogoliubov-de Gennes equation as a singular integral equation. The latter is of a novel hypersingular type, in having a kernel which is hypersingular at only two isolated points. 
Deriving its solution, we show that the integral equation reveals  
a continuum of evanescent channels at the sound barrier which is absent for a purely contact-interaction condensate. We furthermore demonstrate that by performing a discrete approximation for the 
kernel, one achieves an excellent solution accuracy for already a moderate number of discretization steps. 
Finally, we show that the non-monotonic 
nature of the system dispersion, corresponding to the emergence of a roton minimum in the excitation spectrum, 
results in peculiar features of the transmission and reflection at the sound barrier  
which are nonexistent for contact interactions.
ER  -

@Article{10.21468/SciPostPhysCore.6.1.003,
	title={{Nonlocal field theory of quasiparticle scattering in dipolar Bose-Einstein condensates}},
	author={Caio C. Holanda Ribeiro and Uwe R. Fischer},
	journal={SciPost Phys. Core},
	volume={6},
	pages={003},
	year={2023},
	publisher={SciPost},
	doi={10.21468/SciPostPhysCore.6.1.003},
	url={https://scipost.org/10.21468/SciPostPhysCore.6.1.003},
}