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Response to Comment on ‘Non-representative Quantum Mechanical Weak Values’ by Ben-Israel and Vaidman


Ben-Israel and Vaidman (Found Phys 47:467–470, 2017) have raised objections to my arguments that there are cases where a quantum mechanical weak value can be said not to represent the system to which it pertains. They are correct in pointing out that some of my conclusions were too general. However, for weak values of projection operators my conclusions still stand.

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  1. An analogy to this situation, although not a perfect one, could be an ordinary function f(x) which for small \(x > 0\) has an expansion \(f(x) = a x + 0(x^{2})\). It is continuous at x = 0. But now consider instead (1 / x)f(x). Then \({lim}_{x \rightarrow 0}[(1/x) f(x)] = a\), while for \(x = 0 \) the expression (1 / x)f(x) is undefined = 0/0 .


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I am grateful to Johan Bijnens for a careful reading of the manuscript.

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Correspondence to B. E. Y. Svensson.

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Svensson, B.E.Y. Response to Comment on ‘Non-representative Quantum Mechanical Weak Values’ by Ben-Israel and Vaidman. Found Phys 47, 1258–1260 (2017).

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  • Weak values
  • Representative weak values
  • Projector weak values
  • Discontinuous limits