Abstract
A single, trapped and ultracold molecular hydrogen ion is an attractive quantum system for exploring various aspects of fundamental physics, such as the determination of fundamental constants and testing their time-independence. Here we demonstrate, for the first time, controlled loading, sympathetic cooling, mass spectrometric identification, and vibrational excitation of ultracold single HD ions trapped in a tightly confining radiofrequency trap using single laser-cooled Be
ions for sympathetic cooling. The apparatus can be used also for preparing other single ions, both lighter and heavier than the coolant ion.
GRAPHICAL ABSTRACT
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Acknowledgments
The authors are grateful to Prof. Johannes Hecker Denschlag's group (Universität Ulm) for providing their trap's CAD files. We are indebted to M. G. Hansen for his assistance on frequency stabilisation of the Doppler cooling laser, to S. Alighanbari for his help with the HD+ spectroscopy and photodissociation lasers, and to both for their insights and stimulating discussions. M.S., G.G. and C.W. acknowledge a fellowship from the Professor W. Behmenburg-Schenkung.
Disclosure statement
No potential conflict of interest was reported by the author(s).