Ultrabroadband direct detection of nonclassical photon statistics at telecom wavelength

Kentaro Wakui, Yujiro Eto, Hugo Benichi, Shuro Izumi, Tetsufumi Yanagida, Kazuhiro Ema, Takayuki Numata, Daiji Fukuda, Masahiro Takeoka, Masahide Sasaki

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


Broadband light sources play essential roles in diverse fields, such as high-capacity optical communications, optical coherence tomography, optical spectroscopy, and spectrograph calibration. Although a nonclassical state from spontaneous parametric down-conversion may serve as a quantum counterpart, its detection and characterization have been a challenging task. Here we demonstrate the direct detection of photon numbers of an ultrabroadband (110 nm FWHM) squeezed state in the telecom band centred at 1535 nm wavelength, using a superconducting transition-edge sensor. The observed photon-number distributions violate Klyshko's criterion for the nonclassicality. From the observed photon-number distribution, we evaluate the second- and third-order correlation functions, and characterize a multimode structure, which implies that several tens of orthonormal modes of squeezing exist in the single optical pulse. Our results and techniques open up a new possibility to generate and characterize frequency-multiplexed nonclassical light sources for quantum info-communications technology.

Original languageEnglish
Article number4535
JournalScientific reports
Publication statusPublished - 2014 Apr 3
Externally publishedYes

ASJC Scopus subject areas

  • General


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