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Updated: Aug 24, 2026

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
Published on: May 30, 2014
Homodyne tomography characterization and nonlocality of a dual-mode optical qubit
S A Babichev1, J Appel, A I Lvovsky
1Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany.
Abstract:
A single photon, delocalized over two optical modes, is characterized by means of quantum homodyne tomography. The reconstructed four-dimensional density matrix extends over the entire Hilbert space and thus reveals, for the first time, complete information about the dual-rail optical quantum bit as a state of the electromagnetic field. The experimental data violate the Bell inequality albeit with a loophole similar to the detection loophole in photon counting experiments.
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