An entangled state prepared in a decoherence free sub-space together with a
Ramsey type measurement can probe parity violation in heavy alkali ions like
Ba+ or Ra+. Here we propose an experiment with Ba+ as an example to measure the
small parity violating effect in this system. It has been shown that a
measurement on a maximally correlated system will reduce the uncertainty as
compared to that on a single ion measurement. In addition it also provides a
feasible solution to measure the nuclear spin dependent part of the total
parity violating light shift in an ionic system which has so far not been
addressed.Comment: 4 pages, 3 figure