Creation of a low-entropy quantum gas of polar molecules in an optical lattice

• Published in: arXiv.org 2015-07
• Main Authors: Moses, Steven A, Covey, Jacob P, Miecnikowski, Matthew T, Yan, Bo, Gadway, Bryce, Ye, Jun, Jin, Deborah S
• Format: Article
• Language: English
• Subjects: Chemical synthesis; Entropy; Gases; Magnetism; Optical lattices; Quantum entanglement; Quantum statistics
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1507.02377

Ultracold polar molecules, with their long-range electric dipolar interactions, offer a unique platform for studying correlated quantum many-body phenomena such as quantum magnetism. However, realizing a highly degenerate quantum gas of molecules with a low entropy per particle has been an outstanding experimental challenge. In this paper, we report the synthesis of a low entropy molecular quantum gas by creating molecules at individual sites of a three-dimensional optical lattice that is initially loaded from a low entropy mixture of K and Rb quantum gases. We make use of the quantum statistics and interactions of the initial atom gases to load into the optical lattice, simultaneously and with good spatial overlap, a Mott insulator of bosonic Rb atoms and a single-band insulator of fermionic K atoms. Then, using magneto-association and optical state transfer, we efficiently produce ground-state molecules in the lattice at those sites that contained one Rb and one K atom. The achieved filling fraction of 25% indicates an entropy as low as \(2.2\,k_B\) per molecule. This low-entropy molecular quantum gas opens the door to novel studies of transport and entanglement propagation in a many-body system with long-range dipolar interactions.