Cloning entangled photons to scales one can see

Journal Article · Mon Nov 15 04:00:00 EST 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.82.053814· OSTI ID:21528730

Sekatski, Pavel; Sanguinetti, Bruno; Pomarico, Enrico; Gisin, Nicolas ^[1]; Simon, Christoph ^[2]

---

1. Group of Applied Physics, University of Geneva, 20 rue de l'Ecole-de Medecine, CH-1211 Geneva 4 (Switzerland)
2. Institute for Quantum Information Science and Department of Physics and Astronomy, University of Calgary, Calgary T2N 1N4, Alberta (Canada)

By amplifying photonic qubits it is possible to produce states that contain enough photons to be seen with the human eye, potentially bringing quantum effects to macroscopic scales [P. Sekatski, N. Brunner, C. Branciard, N. Gisin, and C. Simon, Phys. Rev. Lett. 103, 113601 (2009)]. In this paper we theoretically study quantum states obtained by amplifying one side of an entangled photon pair with different types of optical cloning machines for photonic qubits. We propose a detection scheme that involves lossy threshold detectors (such as the human eye) on the amplified side and conventional photon detectors on the other side. We show that correlations obtained with such coarse-grained measurements prove the entanglement of the initial photon pair and do not prove the entanglement of the amplified state. We emphasize the importance of the detection loophole in Bell violation experiments by giving a simple preparation technique for separable states that violate a Bell inequality without closing this loophole. Finally, we analyze the genuine entanglement of the amplified states and its robustness to losses before, during, and after amplification.

• OSTI ID: 21528730
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 5 Vol. 82; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLIFICATION
BELL THEOREM
BOSONS
CLONING
DETECTION
ELEMENTARY PARTICLES
INFORMATION
MASSLESS PARTICLES
MEASURING INSTRUMENTS
NEUTRON DETECTORS
PHOTONS
QUANTUM ENTANGLEMENT
QUANTUM INFORMATION
QUANTUM STATES
QUBITS
RADIATION DETECTORS
THRESHOLD DETECTORS