The quantum world writ large: Using short optical pulses to study macroscopic quantum behavior

Einstein infamously dismissed quantum entanglement as spooky action at a distance and quantum uncertainty with his quip that God does not play dice with the universe. Aside from revealing his conceptual prejudices, Einstein’s rejection of these now-established hallmarks of quantum mechanics point to the field’s elusive nature: Coherent quantum mechanical phenomena, such as entanglement and superposition, are not apparent at macroscopic levels of scale. In fact, a common view is that on these scales quantum behavior is masked by decoherence, or even that quantum mechanics itself needs revision. Encouragingly, however, researchers at the Vienna Center for Quantum Science and Technology (VCQ), University of Vienna, have recently proposed an experimental design that would use a macroscopic mechanical resonator, short optical pulses and optical microcavities to realize quantum state tomography, squeezing, and state purification that could shed light on this elusive boundary between the quantum and classical worlds.