Quantum control of ultracold polar molecules

Lead Research Organisation: Imperial College London
Department Name: Dept of Physics

Abstract

A gas of ultracold polar molecules, arranged as a regular array, will make an ideal quantum simulator of strongly-interacting quantum systems. This project will focus on creating this system, starting from molecules captured in a magneto-optical trap. The first part of the project is to investigate sub-Doppler cooling processes in the molecular magneto-optical trap and use these to cool the molecules to sub-milliKelvin temperatures. The next step will be to investigate collisions between atoms and molecules at ultracold temperatures. This will be done by overlapping a cloud of cold molecules with a cloud of ultracold atoms, first in a magneto-optical trap, then in a magnetic trap, and finally in a microwave trap. There is currently very little information about elastic and inelastic collisional processes at these very low temperatures, so this investigation will yield a wealth of new knowledge. Using the results of this study, we will sympathetically cool the molecules using the atoms. By driving an evaporative cooling process, the atoms can be cooled to sub-micro-Kelvin temperatures while keeping the molecules in thermal equilibrium with the atoms through elastic collisions. This provides a route to a dense gas of ultracold polar molecules. Finally, single molecules from this gas will be captured using optical tweezer traps, and the coherent manipulation of individual molecules and molecule pairs will be investigated.

Publications

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Blackmore J (2018) Ultracold molecules for quantum simulation: rotational coherences in CaF and RbCs in Quantum Science and Technology

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Caldwell L (2019) Deep Laser Cooling and Efficient Magnetic Compression of Molecules. in Physical review letters

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Caldwell L (2020) Long Rotational Coherence Times of Molecules in a Magnetic Trap. in Physical review letters

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Truppe S (2017) Molecules cooled below the Doppler limit in Nature Physics

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Williams H (2017) Characteristics of a magneto-optical trap of molecules in New Journal of Physics

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Williams HJ (2018) Magnetic Trapping and Coherent Control of Laser-Cooled Molecules. in Physical review letters

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509486/1 01/10/2016 30/09/2021
1858373 Studentship EP/N509486/1 01/11/2016 30/04/2020 Luke Caldwell
 
Description - Molecules have been cooled to about 1 millikelvin by Doppler cooling in a magneto-optical trap and further cooled to 5 microkelvin using sub-Doppler cooling processes
- Ultracold molecules have been trapped magnetically, for up to 5 seconds, in selectable rotational, hyperfine and Zeeman states
- Rotational superposition states have been prepared and are found to survive for several milliseconds
- Mixtures of ultracold atoms and molecules have been prepared and their collisions have been studied.
Exploitation Route The trapped ultracold molecules produced could be used for: 1) testing particle physics theories that go beyond the standard model; 2) simulation of many-body quantum systems; 3) quantum information processing; 4) improving our understanding of chemistry at the quantum level.
Sectors Education