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Dr. Alessandro Romito

University of Berlin

Tuesday, February 5th, 2013 at 11:00:00 AM  

Conference room Querzoli - LENS - via Nello Carrara 1 - Sesto Fiorentino (Florence)

Published on-line at 05:57:28 PM on Tuesday, January 29th, 2013

Weak measurements in solid state systems: the case of quantum state discrimination

Fundamental aspects of the weak value concept and its application to solid state systems.

The measurement of any observable in quantum mechanics is a probabilistic process described by the projection postulate. As opposed to projective (strong) measurement, weakly measuring an observable (i.e. measuring it while weakly disturbing the system), provides only partial information on the state of the system. It has been proposed that a two-step procedure - weak measurement followed by a strong one, where the outcome of the first measurement is kept provided a second post-selected outcome occurs - leads to a so-called weak value (10.1103/PhysRevLett.60.1351). Such a weak value may lie well beyond the range of strong values and may happen to be complex. This concept found successful applications in foundation of quantum mechanics, quantum optics, and, recently, in solid state systems.

In the talk I will review the fundamental aspects of the weak value concept and its realization is solid state systems. I will then focus on the recently proposed application of weak-measurement-based protocols to quantum state discrimination, leading to an amplified signal to noise ratio in discriminating between unknown states. I will present a recent experiment in quantum optics proving the validity of such amplification procedure and discuss further applications to solid state systems (image from Wikipedia).

For further informations, please contact Dr. Augusto Smerzi.