Skip to content

Sub-Shot-Noise Transmission Measurement Enabled by Active Feed-Forward of Heralded Single Photons

Research output: Contribution to journalArticle

Original languageEnglish
Article number014016
Number of pages6
JournalPhysical Review Applied
DateAccepted/In press - 10 Jun 2017
DatePublished (current) - 17 Jul 2017


Harnessing the unique properties of quantum mechanics offers the possibility of delivering alternative technologies that can fundamentally outperform their classical counterparts. These technologies deliver advantages only when components operate with performance beyond specific thresholds. For optical quantum metrology, the biggest challenge that impacts on performance thresholds is optical loss. Here, we demonstrate how including an optical delay and an optical switch in a feed-forward configuration with a stable and efficient correlated photon-pair source reduces the detector efficiency required to enable quantum-enhanced sensing down to the detection level of single photons and without postselection. When the switch is active, we observe a factor of improvement in precision of 1.27 for transmission measurement on a per-input-photon basis compared to the performance of a laser emitting an ideal coherent state and measured with the same detection efficiency as our setup. When the switch is inoperative, we observe no quantum advantage.

    Research areas

  • Quantum Metrology, Quantum optics

    Structured keywords

  • Bristol Quantum Information Institute
  • QETLabs

Download statistics

No data available



  • Full-text PDF (final published version)

    Rights statement: This is the final published version of the article (version of record). It first appeared online via APS at . Please refer to any applicable terms of use of the publisher.

    Final published version, 341 KB, PDF document

    Licence: CC BY


View research connections

Related faculties, schools or groups