Abstract
To illustrate the loss problem I take the example of quantum metrology where for interferometric measurement of an optical phase θ, the fundamental limit or the standard quantum limit (SQL) Δθ ≥ 1/√n where n is the number of photons detected. In theory using entangled photons it is possible to beat the SQL and achieve the Heisenberg limit Δθ ≥ 1/n. However this involves detecting the photons in n-fold sets which implies losses will go as Ln while in the classical case photons are detected individually and n=1. As a result recent metrology experiments ‘beating the quantum limit’ actually only do so in the artificial case where losses are factored out.
© 2013 IEEE
PDF ArticleMore Like This
A. R. McMillan, B. Bell, A. S. Clark, L. Labonté, S. Kannan, W. McCutcheon, T. Wu, A. Martin, O. Alibart, S. Tanzilli, W. J. Wadsworth, and J. G. Rarity
LTu4G.3 Laser Science (LS) 2013
R. Demkowicz-Dobrzański, M. Kacprowicz, W. Wasilewski, K. Banaszek, U. Dorner, B. J. Smith, J. S. Lundeen, and Ian A. Walmsley
EE_P2 European Quantum Electronics Conference (EQEC) 2009
Shigeki Takeuchi
FW4C.1 Frontiers in Optics (FiO) 2013