Towards realising long range interaction of strontium-88 atoms

Ramchurn, Preetam (2022). Towards realising long range interaction of strontium-88 atoms. University of Birmingham. Ph.D.

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Abstract

Study of the quantum phenomena present in interacting ultracold gases has led to many fascinating discoveries and applications, such as quantum computing and more precise measuring of time to amazing accuracy of 1 part in 10\(^{-18}\). The future of innovation lies within the world of the small and so many physicists have devoted their efforts into probing into this frontier.

This thesis is concerned with manipulating atoms in the alkaline earth metal, strontium-88, which have the property of long-range dipolar interactions that come about from coherent exchange of photons on the \(^3\)P\(_0 \rightarrow ^3\)D\(_1\) transition. A look back into the historical developments of the techniques used for long range interaction experiments is shown, followed by the present methods used for achieving laser cooling and magneto-optical traps (MOTs). This is followed by a description of the experimental setup used inside of the lab to cool and trap approximately 1 billion Sr atoms to temperatures of 1.1 mK at a density of 10\(^{11}\) cm\(^{-3}\) inside of a blue MOT. The lifetime of the trapped \(^3\)P\(_2\) state is shown to be 1.1 seconds. Zeeman sideband spectroscopy allows measurement of the Landé g factor of \(^3\)D\(_1\) state which is shown to be 0.4995(88) which is in good agreement with the theoretical Landé g factor value of 0.4988. The 2.6 µm laser is currently free running but a specialised cavity housed within a titanium chamber has been created to allow stabilisation.

Further plans for the future of this experiment are outlined as circumstances did not allow these to be completed. After construction of the novel adjustable length 2.6 µm cavity, the next step would have been to integrate this into the experiment. This should increase the number of the captured atoms and perform even better Zeeman spectroscopy. The plan is to then develop the cross laser trap for the dipole 1.06 µm laser. Further evaporative cooling could be performed on the MOT with this installed to achieve denser samples of atoms. This BEC would use a different isotope of \(^{84}\)Sr due to its much better elastic scattering compared with that of \(^{88}\)Sr which actually has a negative value of -2. The optical lattice for the sample can also be performed using the 813 nm laser, frequency doubled to 412 nm and even more upgrades to the vacuum system can be made for better results.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):