Speaker: Professor Xia-Ji Liu
Affiliation: Centre for Quantum and Optical Science, Swinburne University of Technology

Abstract

Over the past few years, a newly discovered phase of ultracold, dilute quantum droplets has attracted increasingly attention in different fields of physics. In sharp contrast to other gas-like phases in containers, quantum droplets are self-bound, liquid-like clusters of ten to hundred thousands of atoms in free space, formed by the delicate balance between the attractive mean-field force and repulsive force from quantum fluctuations.

 In this talk, I will give our theoretical progress in two-component Bose-Bose mixtures. We revisit the Bogoliubov theory of quantum droplets proposed by Petrov [Phys. Rev. Lett. 115, 155302 (2015)], where the mean-field collapse is stabilized by the Lee-Huang-Yang quantum fluctuations. We show that a loophole in Petrov's theory, i.e., the ignorance of the softening complex Bogoliubov spectrum, can be naturally removed by the introduction of bosonic pairing. The pairing leads to weaker mean-field attractions, and also stronger Lee-Huang-Yang term in the case of unequal intraspecies interactions. As a result, the equilibrium density for the formation of self-bound droplets significantly decrease in the deep droplet regime, in agreement with a recent observation from diffusion Monte Carlo simulations. Our construction of a consistent pairing theory of ultradilute quantum droplet may also be relevant to understand the supersolid in dipolar gases.

About Australia - New Zealand Cold Atom Seminars

This new initiative hosts a seminar once a month for the Australia – New Zealand cold atom research community.  The purpose is to encourage and facilitate ongoing discussions and collaboration in the local community.  Talks should be less than 40 minutes in length to allow ample time for questions and discussion.

Seminars will be held on the last Friday of the month (except for December) at 1pm Melbourne time (which is normally 3pm New Zealand time).  While the primary format is online via Zoom, various institutions will host the seminar in local seminar rooms.  The Zoom link is https://uqz.zoom.us/j/88604569495

You can sign up for announcements for the seminars at this webpage:
https://lists.science.uq.edu.au/mailman/listinfo/anz_coldatoms

Seminars are recorded, and past seminars can be accessed from this web page.

Contact Matthew Davis mdavis@physics.uq.edu.au for further information.

 

Venue

Physics Annexe (06)
Room: 
409 (or via Zoom https://uqz.zoom.us/j/88604569495)