Abstract
Quantum multiphoton interferometry has now reached the six-photon stage. Thus far, the observed fidelities of entangled states never reached . We report a high fidelity (estimated at 88%) experiment in which six-qubit singlet correlations were observed. With such a high fidelity we are able to demonstrate the central property of these “singlet” correlations, their “rotational invariance,” by performing a full set of measurements in three complementary polarization bases. The patterns are almost indistinguishable. The data reveal genuine six-photon entanglement. We also study several five-photon states, which result upon detection of one of the photons. Multiphoton singlet states survive some types of depolarization and are thus important in quantum communication schemes.
- Received 18 March 2009
DOI:https://doi.org/10.1103/PhysRevLett.103.150501
©2009 American Physical Society
Viewpoint
Protecting quantum superpositions from the outside world
Published 5 October 2009
An entangled state of six photons could potentially carry quantum information over large distances and between different reference frames.
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