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Phys. Rev. A 60, R773 - R776 (1999)

Ultrabright source of polarization-entangled photons

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Paul G. Kwiat1, Edo Waks1 *, Andrew G. White1, Ian Appelbaum1 †, and Philippe H. Eberhard2
1Physics Division, P-23, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
2Lawrence Berkeley Laboratory, University of California at Berkeley, Berkeley, California 94720

Rapid Communication Received 2 October 1998

Using the process of spontaneous parametric down-conversion in a two-crystal geometry, we have generated a source of polarization-entangled photon pairs that is more than ten times brighter, per unit of pump power, than previous sources, with another factor of 30 to 75 expected to be readily achievable. We have measured a high level of entanglement between photons emitted over a relatively large collection angle, and over a 10-nm bandwidth. As a demonstration of the source capabilities, we obtained a 242-σ violation of Bell’s inequalities in less than three minutes, and observed near-perfect photon correlations when the collection efficiency was reduced. In addition, both the degree of entanglement and the state purity should be readily tunable.


©1999 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevA.60.R773
DOI: 10.1103/PhysRevA.60.R773
PACS: 42.50.Dv, 03.65.Bz, 03.67.-a

* Present address: Ginzton Laboratory, Stanford University, Stanford, CA 94305.
† Present address: Physics Department, MIT, Cambridge, MA 02139.

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