CAREER: Two-Dimensional Quantum Fabric of Ultracold Dipolar Molecules

Understanding and controlling fundamental properties of materials is a major frontier of physics. From hardened steel in the industrial revolution to the doped silicon used in the electronics era, new ways to understand and control materials often leads to new technology. In a physics perspective, materials are generally made of densely packed atoms with positively charged ionic cores permeated by a negatively charged gas of electrons. We know the movement of electrons and ions is governed by quantum mechanics. However, understanding exactly how this motion gives rise to material properties such as superconductivity and exotic forms of magnetism is a major challenge. This is challenging, in part, because it is difficult to observe individual electrons. They are small; they move quickly; they interact with each other, and they are easily disturbed. To address this challenge with a new approach, this project aims to use gasses of ultracold molecules in vacuum to simulate electrons in materials. Interactions between molecules are expected to make phenomena such as the self-organization of crystalline phases easier to observe. This team will assemble polar molecules atom-by-atom at ultracold temperatures and then trap molecules in a thin sheet of laser light. While confined in one dimension, the molecules will still be free to move in two dimensions and interact with each other. This project will explore how to use this quantum mechanical 'fabric' of dipolar molecules to simulate properties of real materials and to study fundamental organizing principles of matter.

The team will construct a new apparatus to study two-dimensional quantum systems of ultracold dipolar molecules. The objectives include (1) the creation of a novel quantum gas mixture of sodium and cesium atoms. (2) The creation of dense ultracold samples of sodium-cesium molecules in the absolute ground state. (3) The investigation of molecular gases in a single two-dimensional sheet via high-resolution imaging. Sodium-cesium molecules have a large electric dipole moment (the largest among the chemically stable bialkali molecules). Utilizing the molecules' dipole moment, this team aims to explore parameter regimes that were inaccessible so far, and which may enable the observation of novel many-body quantum phases such as strongly correlated superfluidity, supersolidity, and the formation of a dipolar crystal. In addition to the technical effort, the project is accompanied by a broad outreach program that aims to improve literacy in quantum physics among high school students, undergraduate students, and high school science teachers.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.