Entanglement with negative Wigner function of almost 3,000 atoms heralded by one photon

Entanglement with negative Wigner function of almost 3,000 atoms heralded by one photon

Quantum-mechanically correlated (entangled) states of many particles are of interest in quantum information, quantum computing and quantum metrology. Metrologically useful entangled states of large atomic ensembles have been experimentally realized, but these states display Gaussian spin distribution functions with a non-negative Wigner quasiprobability distribution function. NonGaussian entang...

Heralded entanglement between widely separated atoms.

Entanglement is the essential feature of quantum mechanics. Notably, observers of two or more entangled particles will find correlations in their measurement results that cannot be explained by classical statistics. To make it a useful resource, particularly for scalable long-distance quantum communication, the heralded generation of entanglement between distant massive quantum systems is neces...

Entanglement versus negative domains of Wigner functions

Probing negative values of a Wigner function in scattering of Schrödinger cats by atoms

Within a plane-wave approximation in scattering, an incoming wave packet’s Wigner function stays everywhere positive, which obscures such quantum phenomena as non-locality and entanglement. With the advent of the modern electron microscopes with subnanometer-sized beams one can enter the genuinely quantum regime where the latter effects become only moderately attenuated. Here we show how to pro...

Probing the negative Wigner function of a pulsed single photon point by point.

We investigate quantum properties of pulsed light fields point by point in phase space. We probe the negative region of the Wigner function of a single photon generated by the means of waveguided parametric down conversion. This capability is achieved by employing loss-tolerant photon-number resolving detection, allowing us to directly observe the oscillations of the photon statistics in depend...