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In quantum mechanics the measuremen process is associated with the collapse of the wave function, according to the projection postulate [1].
Alternatively, via a weak measurment, one can weakly disturb the system during the measurement, obtaining only partial information about the state of the system.
It has been proposed [2] 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 weak value [2]. Remarkably, such a weak value may lie well beyond the range of strong values and may happen to be complex.
Here we present the first proposal to observe the weak value in a solid state device [3]. Specifically we consider a protocol to determine the weak value of electron spin in a double quantum dot with a quantum point contact to be used as a detector. The proposed experiment is realizable with the present-day technology. We also show how to incorporate the adverse effect of decoherence into this procedure.
[1] J. von Neumann, Mathematische Grundlagen der Quantemechanik (Springer-Verlag, Berlin, 1932). [2] Y. Aharonov, D. Z. Albert, L. Vaidman, Phys. Rev. Lett. 60, 1351-1354 (1988). [3] A. Romito, Y. Gefen, and Ya. Blanter, Phys. Rev. Lett. 100, 056801 (2008). |
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