Abstract

Optical implementations of quantum information processing use single photons as quantum bits, for communication and computing purposes. Single-photon detectors are a key enabling technology for this application, as well as for other areas of photonics. A recent single-photon detector technology is based on superconducting nanowires, where the absorption of one or few photons produces a resistive transition and thus a measurable voltage pulse. These nanowire detectors provide unmatched sensitivity and speed throughout the visible and near-infrared spectrum and are now considered as a key technology in optical quantum information processing. In this talk I will focus on the use of nanowires as multi-photon detectors and show that arrays of nanowire structures can function as photon-number-resolving detectors [1], i.e. provide an output pulse proportional to the number of absorbed photons. Additionally, it will be shown that a simple, point-like constriction in a wire can act as a very sensitive, nanoscale n-photon detector, with a threshold set by the bias current [2]. This nanodetector can be used to map the diffraction pattern of single- and multi-photon fields with submicrometer spatial resolution, and as a ps optical autocorrelator working at the single-photon level.

 

  [1] A. Divochiy, et al., “Superconducting nanowire photon number resolving detector at telecom wavelength”, Nature Photonics, 2, 302 (2008)

[2] D. Bitauld, et al., “Nanoscale optical detector with single-photon and multiphoton sensitivity”, Nano Lett., 10, 2977 (2010)