Nonclassicality and entanglement for wave packets

Mode-entanglement-based criteria and measures become insufficient for broadband emission, e.g., from spasers (plasmonic nanolasers). We introduce criteria and measures for the (i) total entanglement of two wave packets, (ii) entanglement of a wave packet with an ensemble, and (iii) total nonclassicality of a wave packet. We discuss these criteria in the context of (i) entanglement of two wave packets emitted from two initially entangled cavities (or two initially entangled atoms) and (ii) entanglement of an emitted wave packet with an ensemble or atom for spontaneous emission and single-photon superradiance. We also show that, (iii) when two constituent modes of a wave packet are entangled, this creates nonclassicality in the wave packet as a noise reduction below the standard quantum limit. The criteria we introduce are all compatible with near-field detectors.