Paradoxical consequences of multipath coherence: perfect interaction-free measurements
Z. Zhao , S. Mondal , M. Markiewicz , Adam Rutkowski , B. Dakić , Wiesław Laskowski , Tomasz Paterek
AbstractQuantum coherence can be used to infer the presence of a detector without triggering it. Here we point out that, according to quantum mechanics, such interaction-free measurements cannot be perfect, i.e., in a single-shot experiment one has strictly positive probability to activate the detector. We formalize the extent to which such measurements are forbidden by deriving a trade-off relation between the probability of activation and the probability of an inconclusive interaction-free measurement. Our description of interaction-free measurements is theory independent and allows derivations of similar relations in models generalizing quantum mechanics. We provide the trade-off for the density cube formalism, which extends the quantum model by permitting coherence between more than two paths. The trade-off obtained hints at the possibility of perfect interaction-free measurements and indeed we construct their explicit examples. Such measurements open up a paradoxical possibility where we can learn by means of interference about the presence of an object in a given location without ever detecting a probing particle in that location. We therefore propose that absence of perfect interaction-free measurement is a natural postulate expected to hold in all physical theories. As shown, it holds in quantum mechanics and excludes the models with multipath coherence.
|Journal series||Physical Review A - Atomic, Molecular, and Optical Physics, ISSN 1050-2947, e-ISSN 1094-1622, (A 35 pkt)|
|Publication size in sheets||0.6|
|Score||= 35.0, 04-12-2019, ArticleFromJournal|
|Publication indicators||= 0; : 2017 = 0.886; : 2014 = 2.808 (2) - 2014=2.628 (5)|
|Citation count*||1 (2020-01-21)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.