Experimental Investigation of Quantum Decay at Short, Intermediate, and Long Times via Integrated Photonics

The decay of an unstable system is usually described by an exponential law. Quantum mechanics predicts strong deviations of the survival probability from the exponential: Indeed, the decay is initially quadratic, while at very large times it follows a power law, with superimposed oscillations. The l...

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Bibliographic Details
Published in:Physical review letters 2019-04, Vol.122 (13), p.130401-130401, Article 130401
Main Authors: Crespi, Andrea, Pepe, Francesco V, Facchi, Paolo, Sciarrino, Fabio, Mataloni, Paolo, Nakazato, Hiromichi, Pascazio, Saverio, Osellame, Roberto
Format: Article
Language:English
Subjects:
Coherent light
Decay
Evolution
Optical waveguides
Photonics
Power law
Quantum mechanics
Quantum theory
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Summary:The decay of an unstable system is usually described by an exponential law. Quantum mechanics predicts strong deviations of the survival probability from the exponential: Indeed, the decay is initially quadratic, while at very large times it follows a power law, with superimposed oscillations. The latter regime is particularly elusive and difficult to observe. Here we employ arrays of single-mode optical waveguides, fabricated by femtosecond laser direct inscription, to implement quantum systems where a discrete state is coupled and can decay into a continuum. The optical modes correspond to distinct quantum states of the photon, and the temporal evolution of the quantum system is mapped into the spatial propagation coordinate. By injecting coherent light states in the fabricated photonic structures and by measuring a small scattered fraction of such light with an unprecedented dynamic range, we are able to experimentally observe not only the exponential decay regime, but also the quadratic Zeno region and the power-law decay at long evolution times.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.122.130401