×

Multiphoton entanglement and interferometry. (English) Zbl 1020.81003

Summary: Multiphoton entanglement is the basis of many quantum communication schemes, quantum cryptographic protocols, and fundamental tests of quantum theory. Spontaneous parametric down-conversion is the most effective source for polarization entangled photon pairs. Here we show, that a class of entangled 4-photon states can be directly created by parametric down-conversion. These states exhibit perfect quantum correlations and a high robustness of entanglement against photon loss. Therefore these states are well suited for new types of quantum communication.

MSC:

81P68 Quantum computation
81V80 Quantum optics
81-05 Experimental work for problems pertaining to quantum theory
94A05 Communication theory
94A60 Cryptography
PDFBibTeX XMLCite
Full Text: DOI arXiv