  Einstein-Podolsky-Rosen steering is a form of quantum nonlocality exhibiting
an inherent asymmetry between the observers, Alice and Bob. We present a simple
class of entangled two-qubit states which are one-way steerable, considering
arbitrary projective measurements. That is, Alice can steer the state of Bob,
but it is impossible for Bob to steer Alice's state. This shows that the
nonlocal properties of entangled states can be fundamentally asymmetrical.
