Improving measurement precision with Weak Measurements

by Yaron Kedem (Nordita)

Tuesday 5 Nov 2013, 11:00 → 12:00 Europe/Stockholm

Nordita West (122:026)

The weak measurement protocol, introduced by Aharonov, Albert and Vaidman 25 years ago, is now in widespread use. They showed that weak coupling of a measurement device to a quantum system, together with a postselection, can yield an intriguing quantity which was named The Weak Value. In some contexts an observable on the system can be replaced by its Weak Value, even though it can be much larger than any of its eigenvalues and is also complex in general. The method of weak measurements have been shown to be highly useful both for the analysis of fundamental issues in quantum mechanics and for practical applications such as precision improvement. We will start with a review of the formalism and then discuss a recent development regarding the enhancement of the Signal to Noise Ratio for precision measurements in the presence of technical noise. We will see that when imaginary weak values are used, such a noise can improve the precision.