Weak Values: a Theoretical Concept and a Practical Tool

TYPETheor./Math. Physics Seminar
Speaker:Yaron Kedem
Location:Lewiner Seminar Room (412)

When one measures weakly an observable on a pre- and postselected system, funny things happen. The result, which is called the Weak Value of the observable, can be, for example, much larger than any of its eigenvalues. One can find negative number of particles, or even complex values. 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 enhancement. In my talk, I will start with a review of the formalism and then present two new developments. One is about increasing the Signal to Noise Ratio in precision measurements in the presence of technical noise. I will show that when imaginary weak values are used, such a noise can improve the precision [1]. The other is the new concept of Modular Values which has strong connection to weak values but can be obtained via strong measurements using qubit meter [2]. References: [1]  Using technical noise to increase the signal-to-noise ratio of measurements via imaginary weak values. Y. Kedem Phys. Rev. A 85, 060102(R) (2012) [2]  Modular Values and Weak Values of Quantum Observables Y. Kedem and L. Vaidman Phys. Rev. Lett. 105, 230401 (2010)