Measurement beyond the standard quantum limit
Physics needs measurements which are more and more precise, but any measurement in physics is marred by noise: imperfect preparation of the system to be measured, thermal disturbance, etc. At the most extreme scales this occurs at the level of particles such as photons, and this noise is thus quantum by nature. This is what is known as the Heisenberg limit, a limit which cannot be overcome and which represents the fact that no measurement can be of an absolute and infinite precision. But there are easier ways than others to get closer to this limit. Daniel Braun, of the University of Toulouse, and John Martin, of the University of Liège, have just conceived of a theoretical system which will doubtless aid experimenters and favour applications in numerous scientific disciplines. Their work has just been the subject of a publication in Nature Communications (1). (1) Braun, D. and Martin, J. Heisenberglimited sensitivity with decoherenceenhanced measurements. Nat. Commun. 2:223 doi: 10.1038/ncomms1220 (2011).




