Antibunching and unconventional photon blockade with Gaussian squeezed states

Understand

Photon antibunching is a quantum phenomenon typically observed in strongly nonlinear systems where photon blockade suppresses the probability for detecting two photons at the same time.

• Antibunching has also been reported with Gaussian states, where optimized amplitude squeezing yields classically forbidden values of the intensity correlation, $g^{(2)}(0)<1$.
• As a consequence, observing antibunching is not necessarily a signature of photon-photon interactions.
• To clarify the significance of the intensity correlations, we derive a sufficient condition for deducing if a field is non-Gaussian based on a $g^{(2)}(0)$ measurement.