Experimental study of anomalous heating and trap instabilities in a microscopic137Baion trap

Abstract

A single ${}^{137}{\mathrm{Ba}}^{+}$ ion has been laser cooled to the first few vibrational states of an $80\ensuremath{-}\ensuremath{\mu}\mathrm{m}$ radius rf quadrupole trap. Initial measurements showed no anomalous heating of the vibrational phonon for observation times up to 1 ms, corresponding to a heating rate less than 3.3 phonons/ms at a 95% confidence level. Subsequently we observed the growth of large and unstable bias voltages that were correlated with exposure to the atomic beam. After loading over 250 ions over a period of 720 days the trap became unstable, with ion lifetimes $l1 \mathrm{min}.$ A possible connection between this trap instability and anomalous heating observed in quantum computation experiments is discussed. An isotopically selectively laser cooling method was used to refine ${}^{137}\mathrm{Ba}$ ions out of a naturally abundant cloud.