Experimental Demonstration of Macroscopic Quantum Coherence in Gaussian States

Abstract

We witness experimentally the presence of macroscopic coherence in Gaussian quantum states using a recently proposed criterion (E.G. Cavalcanti and M. Reid, Phys. Rev. Lett. 97, 170405 (2006)). The macroscopic coherence stems from interference between macroscopically distinct states in phase space and we prove experimentally that even the vacuum state contains these features with a distance in phase space of $0.51\pm 0.02$ shot noise units (SNU). For squeezed states we found macroscopic superpositions with a distance of up to $0.83\pm 0.02$ SNU. The proof of macroscopic quantum coherence was investigated with respect to squeezing and purity of the states.

5 pages, 6 figures

References in corpus (11)

• Decoherence, einselection, and the quantum origins of the classical
• Generation of a superposition of odd photon number states for quantum information networks
• Controllable generation of highly nonclassical states from nearly pure squeezed vacua
• An experimental investigation of criteria for continuous variable entanglement
• On the effective size of certain "Schrödinger cat'' like states
• 7 dB quadrature squeezing at 860 nm with periodically-poled KTiOPO4
• A characterization of continuous variable entanglement
• Signatures for generalized macroscopic superpositions
• Time domain Einstein-Podolsky-Rosen correlation
• Verifying continuous variable entanglement of intense light pulses
• Pooling quantum states obtained by indirect measurements

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• Signifying the Schrodinger cat in the context of testing macroscopic realism
• Quantifying the mesoscopic nature of the Einstein-Podolsky-Rosen nonlocality