We review the definition and the concepts of the weak values and some measurement model to extract the weak value. This material is based on the author Ph.D. thesis "Time in Weak Values and Discrete Time Quantum Walk" at Tokyo Institute of Technology (2011).
The main goal of this thesis is to introdude to readers the concept of weak measure- ments in quantum mechanics. Firstly a model of indirect measuremnts is established as an alternative to Von Neumann measurement postulate. This model leads to a possible generalization in a form of weak measurements. Then the concept of postselection is introduced and involved into the issue of weak measurements which leads to the weak values of physical quantities. All these theoretical concepts are presented using simple model examples. Finally, a discussion in provided on the possible interpretation and of weak values and their experimental verification.