The densityfunctional theory of quantum droplets
Abstract
In quantum droplets, the meanfield energy is comparable to the LeeHuangYang (LHY) energy. In the Bogoliubov theory, the LHY energy of the quantum droplet has an imaginary part, but it is neglected for practical purposes. So far, most theoretical studies of quantum droplets have been based on the extended GrossPitaevskii (GP) equation obtained by adding the LHY energy to the GP equation. In this article, we present the densityfunctional theory of quantum droplets. In our approach, the quantum fluctuations in quantum droplets, as described by an effective action, generate the correlation energy which is real and can be determined selfconsistently. Using the densityfunctional theory, we calculate higherorder corrections to the energy, the quantum depletion fraction, and the excitations of the droplet. Our results for the groundstate energy and the quantum depletion fraction are compared with the Monte Carlo results and good agreement is found. The implications of our theory are discussed.
 Publication:

arXiv eprints
 Pub Date:
 May 2023
 DOI:
 10.48550/arXiv.2306.00254
 arXiv:
 arXiv:2306.00254
 Bibcode:
 2023arXiv230600254Z
 Keywords:

 Quantum Physics;
 Condensed Matter  Quantum Gases