The Macroscopic Harmonic Oscillator and Quantum Measurements

Amir Leshem, Omri Gat

We study the emergence of macrorealism in a harmonic oscillator subject to consecutive measurements of a squeezed action. We demonstrate a breakdown of dynamical realism in a wide parameter range that is maximized in a scaling limit of extreme squeezing, where it is based on measurements of smooth observables, implying that macroscopic realism is not valid in the harmonic oscillator. We propose an indirect experimental test of these predictions with entangled photons by demonstrating that local realism in a composite system implies dynamical realism in a subsystem.

Erich W. Schmid, Gerhard Spitz, Wolfgang Lösch

Hyunseok Jeong, Changsuk Noh, Seunglee Bae +2 more

We investigate how to experimentally detect a recently proposed measure to quantify macroscopic quantum superpositions [Phys. Rev. Lett.106, 220401 (2011)10.1103/PhysRevLett.106.220401PRLTAO0031-9007], namely, “macroscopic quantumness” I. Schemes based on overlap measurements for harmonic oscillator states and for qubit states are extensively investigated. Effects of detection inefficiency and coarse-graining are analyzed in order to assess feasibility of the schemes.

Erich W. Schmid, Gerhard Spitz, Wolfgang Lösch

ETTORE MAJORANA, P. Puppo, Piero Rapagnani +1 more

Shu Hotta