Sub-Shot-Noise Transmission Measurement Enabled by Active Feed-Forward of Heralded Single Photons
Javier Sabines-Chesterking, Rebecca Whittaker, Siddarth Koduru Joshi, Patrick M. Birchall, Paul‐Antoine Moreau, Alex R. McMillan, Hugo V. Cable, Jeremy L. O’Brien, John Rarity, Jonathan C. F. Matthews · Physical Review Applied · 2017
The limit of precision in optical measurements is due to quantum fluctuations, which are governed by Poissonian statistics. With a clever setup, however, the authors achieve a precision in transmission measurements that beats this limit, without the selective analysis of recorded data (post-selection). This shows that the single-photon-detector approach, used by many groups worldwide, is viable for real-world optical quantum metrology, not just proof-of-principle tests. In turn, this demonstration unlocks an array of techniques for quantum-state engineering that crucially depend on single-photon detection.