Experimental tests of Bell's inequality allow to distinguish quantum
mechanics from local hidden variable theories. Such tests are performed by
measuring correlations of two entangled particles (e.g. polarization of photons
or spins of atoms). In order to constitute conclusive evidence, two conditions
have to be satisfied. First, strict separation of the measurement events in the
sense of special relativity is required ("locality loophole"). Second, almost
all entangled pairs have to be detected (for particles in a maximally entangled
state the required detector efficiency is 82.8%), which is hard to achieve
experimentally ("detection loophole"). By using the recently demonstrated
entanglement between single trapped atoms and single photons it becomes
possible to entangle two atoms at a large distance via entanglement swapping.
Combining the high detection efficiency achieved with atoms with the space-like
separation of the atomic state detection events, both loopholes can be closed
within the same experiment. In this paper we present estimations based on
current experimental achievements which show that such an experiment is
feasible in future.Comment: 6 pages, 3 figures, to be published in Advanced Science Letter
