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PhD Ceremony Oscar Versolato

14 October 2011

On 14 October Oscar Versolato will defend his thesis 'Laser spectroscopy of trapped Ra+ ions: towards a single-ion optical clock'.

Location: Academy Building, Broerstraat 5, Groningen

Time: 16:15 hrs.

Promotores: K. Jungmann and R.G.E. Timmermans

Laser spectroscopy of trapped Ra+ ions: towards a single-ion optical clock

Asingle trapped and laser-cooled radium ion, Ra+, is a promising candidate for high precision experiments, such as on atomic parity violation (APV) and atomic clocks. APV experiments provide a stringent test of the Standard Model of particles physics with high sensitivity for physics beyond. Ultra-narrow transitions in Ra+can be employed for optical frequency standards, or “clocks”. As an important step towards such experiments excited-state laser spectroscopy was performed on short-lived trapped209-214Ra+ions produced from the AGOR cyclotron at KVI. Hyperfine structure constants of Ra+atomic states and isotope shifts of relevant transitions were studied, providing benchmarks for the required atomic theory at percent level accuracy. The measurement of a lower limit of the lifetime of the meta-stable 6d2D5/2state provides an important confirmation of the fundamental availability of long coherence times in the trapped Ra+system, required for high-quality clocks. The potential of the electric quadrupole transitions 7s2S1/2-6d2D3/2,6d2D5/2in Ra+isotopes as single-ion optical frequency standards was explored. The frequency shifts of the clock transitions due to external fields and corresponding uncertainties were calculated. Several competitive candidates have been identified. In particular, the transition 7s2S1/2(F=2,mF=0)-6d2D3/2(F=0,mF=0) in223Ra+at 828nm wavelength stands out because of the absence of linear Zeeman and electric quadrupole shifts. It could be exploited as a compact, robust, and low-cost atomic clock operating at a fractional frequency uncertainty of 10-17. With more experimental effort, the223,225,226Ra+clocks could be pushed to a projected performance reaching even the 10-18level.

Oscar Versolato (Oldenzaal, 1983) studied Physics and Astronomy in Groningen. The research was financed by an NWO Toptalent scholarship. Versolato will continue in research as a postdoc at the Max Planck Institute in Heidelberg.

Last modified:25 January 2019 11.24 a.m.
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