Physicists at the Institute for Quantum Optics and Quantum Information, the University of Vienna, and the Vienna Center for Quantum Science and Technology have demonstrated in an experiment that the decision whether two particles were in an entangled or in a separable quantum state can be made even after these particles have been measured and may no longer exist.
Gravitational waves, much like the recently discovered Higgs boson, are notoriously difficult to observe. Scientists first detected these ripples in the fabric of space-time indirectly, using radio signals from a pulsar-neutron star binary system. The find, which required exquisitely accurate timing of the radio signals, garnered its discoverers a Nobel Prize. Now a team of astronomers has detected the same effect at optical wavelengths, in light from a pair of eclipsing white dwarf stars.