Periodic Reporting for period 1 - IASMOL (Imaging and Addressing of Single Molecules in Optical Lattices)
Reporting period: 2020-01-01 to 2021-12-31
The notion of quantum simulation - to simulate one quantum system with another - was first proposed by Richard Feynman. It was proposed in order to overcome the problem that some systems cannot be simulated using classical computers. A prominent example of quantum simulation is the study of interacting many-body systems. The “Imaging and Addressing of Single Molecules in Optical Lattices” (IASMOL) project aims to develop techniques to combine the state-of-the-art imaging and addressing techniques currently employed in atomic quantum gas microscopes and apply them to molecule experiments. This will enable the quantum simulation of strongly interacting matter with precise single-particle control and in-situ imaging. I will use molecules created by the association of ultracold alkali-metal atoms. This approach benefits from the enormous advances in laser cooling of atoms and crucially allows the lattice to be loaded with atom-pairs from degenerate atomic gases. Whereas atoms only interact via contact interactions, these ultracold molecules have the advantage of long-range dipole-dipole interactions that can span across multiple lattice sites. Due to delays (covid) we are still working towards these aims.
Although this project has been greatly delayed due to the COVID pandemic, we have made substantial steps towards the project goals. We have optically transported Cs and Rb atoms to the science cell of the vacuum chamber (see attached figure of experimental setup). This separate chamber is required to allow for the high optical access requirements for a quantum gas microscope. We have tested the high resolution imaging setup using a ion beam milled test target in the place of atoms and shown that the setup is suitable for the requirements of imaging individual atoms in an optical lattice We are currently in the process of building the optical lattices required for the quantum gas microscope.
In order to image the different atomic species at the same time, we need a trap that separates the different species. Such a trap can be made with an optical lattice. An optical lattice is created by an interference pattern of overlapping laser beams. The high- and low-intensity regions of light created by the interference pattern create a periodic potential for the particles through the optical dipole force. At certain wavelengths the force can be attractive for one atomic species and repulsive for another species. This is determined by the sign of a property of the atom called the polarizability. This polarizability is wavelength dependent.
Working towards this trap we have studied the tune-out wavelength of Cs around 880 nm. At this tune-out wavelength the polarizability of Cs changes sign. In the vicinity of this wavelength is therefore a suitable regime in which to image the RbCs molecules. In this work (Phys. Rev. A 104, 052813 (2021)), we study the polarizability around this tune-out wavelength and precisely measure the location of this tune-out wavelength.
During the course of this fellowship I have also had the opportunity to study RbCs molecules in a separate experiment. This separate experiment does not have the optical access for creating a high resolution imaging system for a quantum gas microscope. However, it is a ideal experiment for studying fundamental properties of RbCs molecules. We have been able to study both molecule-molecule and atom-molecule collisions. Molecule-molecule collisions are important to understand as they are essential for understanding the large loss of molecules over time. Atom-molecule collisions are important as atoms could be used in the future to further cool the molecules. All these studies have advanced the understanding of bi-alkali molecules, and will be important for future molecular quantum gas microscopes.
In order to image the different atomic species at the same time, we need a trap that separates the different species. Such a trap can be made with an optical lattice. An optical lattice is created by an interference pattern of overlapping laser beams. The high- and low-intensity regions of light created by the interference pattern create a periodic potential for the particles through the optical dipole force. At certain wavelengths the force can be attractive for one atomic species and repulsive for another species. This is determined by the sign of a property of the atom called the polarizability. This polarizability is wavelength dependent.
Working towards this trap we have studied the tune-out wavelength of Cs around 880 nm. At this tune-out wavelength the polarizability of Cs changes sign. In the vicinity of this wavelength is therefore a suitable regime in which to image the RbCs molecules. In this work (Phys. Rev. A 104, 052813 (2021)), we study the polarizability around this tune-out wavelength and precisely measure the location of this tune-out wavelength.
During the course of this fellowship I have also had the opportunity to study RbCs molecules in a separate experiment. This separate experiment does not have the optical access for creating a high resolution imaging system for a quantum gas microscope. However, it is a ideal experiment for studying fundamental properties of RbCs molecules. We have been able to study both molecule-molecule and atom-molecule collisions. Molecule-molecule collisions are important to understand as they are essential for understanding the large loss of molecules over time. Atom-molecule collisions are important as atoms could be used in the future to further cool the molecules. All these studies have advanced the understanding of bi-alkali molecules, and will be important for future molecular quantum gas microscopes.
This project has resulted in two journal articles. These are published freely on arXiv.org in order to reach a wider audience as well as being freely available in the durham research online repository (https://dro.dur.ac.uk/(opens in new window)). The data and analysis are also saved to repositories in the hope that they can be used by others in the future. Research papers are still in preparation including the publication of our work into optical transport.