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

Andrea Crespi, Francesco V. Pepe, Paolo Facchi, Fabio Sciarrino, Paolo Mataloni, Hiromichi Nakazato, Saverio Pascazio, and Roberto Osellame
Phys. Rev. Lett. 122, 130401 – Published 3 April 2019
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Abstract

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.

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  • Received 30 October 2018

DOI:https://doi.org/10.1103/PhysRevLett.122.130401

© 2019 American Physical Society

Physics Subject Headings (PhySH)

General PhysicsQuantum Information, Science & TechnologyAtomic, Molecular & OpticalInterdisciplinary Physics

Authors & Affiliations

Andrea Crespi1,2, Francesco V. Pepe3, Paolo Facchi4,3, Fabio Sciarrino5, Paolo Mataloni5,2, Hiromichi Nakazato6, Saverio Pascazio4,3,7, and Roberto Osellame2,1,*

  • 1Dipartimento di Fisica, Politecnico di Milano, I-20133 Milano, Italy
  • 2Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, I-20133 Milano, Italy
  • 3INFN, Sezione di Bari, I-70126 Bari, Italy
  • 4Dipartimento di Fisica and MECENAS, Università di Bari, I-70126 Bari, Italy
  • 5Dipartimento di Fisica, Sapienza Università di Roma, I-00185 Roma, Italy
  • 6Department of Physics, Waseda University, 169-8555 Tokyo, Japan
  • 7Istituto Nazionale di Ottica (INO-CNR), I-50125 Firenze, Italy

  • *Corresponding author. roberto.osellame@polimi.it

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Issue

Vol. 122, Iss. 13 — 5 April 2019

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