Description
Speaker:
Prof Sadiq Rangwala
Raman Research Institute
Abstract:
We present a new ion trap experiment, with an end cap type Paul trap built for precision spectroscopy and metrology [1,2]. We will discuss the performance of this experiment and then move quickly to the observation of three dimensional trapped ion crystals of Ca+ ions. The crystals form when the ions attain their configuration of minimum energy (CME) as a result of laser cooling of the ions. As the trap anisotropy is tuned, the crystals deform and structural transitions are seen. We study in detail three distinct structural transitions, all of which break symmetry with a change in the parity-odd octopole order parameter. Our observations show spontaneous symmetry breaking illustrated by a Higgs-like mode, dynamical catastrophe resulting in hysterisis, and stochastic switching [3].
In another experiment we study the thermal activation of the spontaneous inversion of a square pyramid ion crystal, which is aided by permutation symmetry and use this paradigm to test the multidimensional Kramers-Langer theory for reaction rates for the first time [4].
References
[1] A. Prakash, A. Ayyadevara, E. Krishnakumar, and S. A. Rangwala, Low divergence cold-wall oven for loading ion traps, Rev. Sci. Instrum. 95, 033202 (2024)
[2] AnandPrakash,AkhilAyyadevara,E.Krishnakumar, M. Ibrahim, K. M. Yatheendran, Subhadeep De, Sayan Patra, S. A. Rangwala, Endcap-Type Paul Trap for Precision Spectroscopy and Studies of Controlled Interactions, arXiv:2601.07328
[3] Akhil Ayyadevara, Anand Prakash, Shovan Dutta, Arun Paramekanti, and S. A. Rangwala, Observing the dynamics of octupolar structural transitions in trapped-ion clusters, arXiv:2505.16378v3 (Accepted PRR)
[4] Akhil Ayyadevara, Anand Prakash, Shovan Dutta, Arun Paramekanti, and S. A. Rangwala, Symmetry-controlled thermal activation in pyramidal Coulomb clusters: Testing Kramers-Langer theory, arXiv:2601.04883