Bipartite temporal Bell inequalities for two-mode squeezed states
  Bipartite temporal Bell inequalities are similar to the usual Bell
inequalities except that, instead of changing the direction of the polariser at
each measurement, one changes the time at which the measurement is being
performed. By doing so, one is able to test for realism and locality, but
relying on position measurements only. This is particularly useful in
experimental setups where the momentum direction cannot be probed (such as in
cosmology for instance). We study these bipartite temporal Bell inequalities
for continuous systems placed in two-mode squeezed states, and find some
regions in parameter space where they are indeed violated. We highlight the
role played by the rotation angle, which is one of the three parameters
characterising a two-mode squeezed state (the other two being the squeezing
amplitude and the squeezing angle). In single-time measurements, it only
determines the overall phase of the wavefunction and can therefore be
discarded, but in multiple-time measurements, its time dynamics becomes
relevant and crucially determines when bipartite temporal Bell inequalities can
be violated. Our study opens up the possibility of new experimental designs for
the observation of Bell inequality violations.
