  Tests such as Bell's inequality and Hardy's paradox show that joint
probabilities and correlations between distant particles in quantum mechanics
are inconsistent with local realistic theories. Here we experimentally
demonstrate these concepts in the time domain, using a photonic entangling gate
to perform nondestructive measurements on a single photon at different times.
We show that Hardy's paradox is much stronger in time and demonstrate the
violation of a temporal Bell inequality independent of the quantum state,
including for fully mixed states.
