Four-photon entanglement from down-conversion

By Harald Weinfurter, Marek Zukowski. 2001

151 citations recorded by the source corpus.

Double-pair emission from type-II parametric down-conversion results in a highly entangled four-photon state. Due to interference, which is similar to bunching from thermal emission, this state is not simply a product of two pairs. The observation of this state can be achieved by splitting the two emission modes at beam splitters and subsequent detection of a photon in each output. Here we describe the features of this state and construct a Bell-type inequality, which gives a necessary and sufficient condition for a four-photon test of local realistic hidden variable theories.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/7cf3db10d92443d3fbff88695197ddb463b67f9b

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In Artificial Intelligence

In Atomic and Molecular Physics, and Optics

Citations in the corpus

Free-Space distribution of entanglement and single photons over 144 km (2006, background): “Entanglement between four photons exists only if they are emitted within the coherence time (about 100 fs in our case); all other instances have to be treated as emission of two uncorrelate”
Multiphoton entanglement and interferometry (2008, background): “Therefore, for the values of the actually chosen measurements the inequality (34) 22 All such inequalities boil down to just a single one X s1=±1 X s2=±1 ˛ ˛E(A1, B1) + s2E(A1, B2) + s1E(A2, B1) + s1s2E(A2, B2) ˛ ˛ ≤ 4, (32) see Weinfurter and Żukowski (2001), Werner and Wolf (2001).”
Entanglement detection (2008, background): “Experimentally, it is remarkable that the state |Ψ2〉 can simply be prepared by a second order process in parametric downconversion [237] (see also Section 6.”