  We show that the detection efficiencies required for closing the detection
loophole in Bell tests can be significantly lowered using quantum systems of
dimension larger than two. We introduce a series of asymmetric Bell tests for
which an efficiency arbitrarily close to 1/N can be tolerated using
N-dimensional systems, and a symmetric Bell test for which the efficiency can
be lowered down to 61.8% using four-dimensional systems. Experimental
perspectives for our schemes look promising considering recent progress in
atom-photon entanglement and in photon hyperentanglement.
