Towards quantum simulation with ultracold polar molecules

Lead Research Organisation: Durham University
Department Name: Physics

Abstract

Ultracold and quantum degenerate atomic gases have been exploited to study a vast array of novel and interesting physical phenomena ranging from fundamental studies of superfluidity to strongly-correlated many body systems. As the field has matured there has been a growing interest in the quest to produce similar gases of molecules, where the rich internal structure offers access to new, fascinating physics. One of the most promising routes to these riches is to exploit the ability to cool atomic gases to degeneracy before associating pairs of atoms to form diatomic molecules. In this context the formation of heteronuclear molecules is of particular interest as, in the ground state, the molecules exhibit a permanent electric dipole moment that gives rise to long-range anisotropic interactions. Such interactions dramatically modify the behaviour of the gas at ultracold temperatures and find many applications. One such application is in the area of quantum simulation where a regular array of interacting molecules confined on a three dimensional optical lattice is used to simulate problems more usually associated with condensed matter physics.
The goal of this project is to explore experimental implementations of quantum simulation protocols using ultracold RbCs molecules. Our studies will investigate the use of rotational states of the molecule to encode a pseudo spin for simulation of quantum magnetism. We will extend the current experimental apparatus to include optical lattices in 1D, 2D and 3D. Ultimately we will develop methods to probe the molecules at the level of single lattice sites in order to gain insight into the complex many-body dynamics in the lattice.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509462/1 01/10/2016 30/09/2021
1735543 Studentship EP/N509462/1 01/10/2016 31/05/2020 Jacob Blackmore
 
Description During the course of this award we have studied the collisional properties of RbCs molecules. We initially found that, despite being chemically nonreactive, a collision between two RbCs molecules contributes towards losses from our apparatus. By using a rapidly switching optical dipole trap we were able to determine that this loss was due to excitation of the intermediate (RbCs)2 complex. We have also studied the behaviour of the internal structure of the RbCs molecule under external fields, we were focussed on the interaction between the molecule and laser fields, we found that there is a complex structure but that it can be greatly simplified by using additional static fields.
Exploitation Route Our studies of the lifetimes show that trapping light limits the lifetime of ultracold molecules. This is applicable to all ultracold molecule experiments worldwide. In the future experiments would benefit from using optical trapping potentials far detuned from transitions in the molecular complex (wavelength> 1 micrometre ) or by using traps which are blue-detuned and so hold the molecules in regions of low intensity. Our studies of the internal structure are applicable to the general bialkali community and should enable an increase in the coherence time of rotational superpositions, necessary for ultracold molecular quantum simulators.
Sectors Other

 
Title Diatomic-Py 
Description Python software for the simulation of singlet-sigma molecular structure. Specifically rotational and hyperfine structure in electromagnetic fields. 
Type Of Technology Physical Model/Kit 
Year Produced 2020 
Open Source License? Yes  
Impact International collaboration from Max Planck Institute in Munich 
URL https://diatomic-py.readthedocs.io/en/latest/