Towards Fast Quantum Gates With Trapped 137Ba Ion

Manchanda, Pawni (2025) Towards Fast Quantum Gates With Trapped 137Ba Ion. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Pawni Manchanda (20MS229)) 20MS229_Thesis_file.pdf Restricted to Repository staff only Download (7MB)

Abstract

This thesis investigates methods for implementing coherent Raman transitions in trapped 137Ba+ ions, aiming towards faster quantum gates. Two distinct schemes for generating phase-coherent Raman lasers are explored in this thesis. The first is frequency filtering using a Fabry–P´erot cavity, and the second is using polarization rotation through a birefringent calcite crystal. While the cavity-based method e↵ectively suppresses destructive sidebands, it introduces significant optical power loss and complexity in phase stabilization. In contrast, the calcite-based approach utilizes frequency-dependent polarization rotation to convert destructive interference into constructive interference without significant power loss. The experimental implementation of this scheme demonstrated ⇡/2 polarization rotation of the Raman sidebands. A coherence metric was used to quantify the efficiency and robustness of the scheme, with both theoretical and experimental results indicating improved performance compared to other existing methods. Additionally, a series of measurements were conducted to investigate non-trivial spectral drifts, revealing relationship between laser frequency, polarization, and temperature fluctuations. These results form the groundwork for future integration of this laser system into ion trap setups for implementing fast single- and two-qubit quantum gates in 137Ba+.

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