Paradoxical consequences of multipath coherence: perfect interaction-free measurements

Z. Zhao , S. Mondal , M. Markiewicz , Adam Rutkowski , B. Dakić , Wiesław Laskowski , Tomasz Paterek


Quantum 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.
Author Z. Zhao
Z. Zhao,,
, S. Mondal
S. Mondal,,
, M. Markiewicz
M. Markiewicz,,
, Adam Rutkowski (FMPI / ITPA)
Adam Rutkowski,,
- Institute of Theoretical Physics and Astrophysics
, B. Dakić
B. Dakić,,
, Wiesław Laskowski (FMPI / ITPA)
Wiesław Laskowski,,
- Institute of Theoretical Physics and Astrophysics
, Tomasz Paterek
Tomasz Paterek,,
Journal seriesPhysical Review A - Atomic, Molecular, and Optical Physics, ISSN 1050-2947, e-ISSN 1094-1622, (A 35 pkt)
Issue year2018
Publication size in sheets0.6
Article number022108
ASJC Classification3107 Atomic and Molecular Physics, and Optics
Languageen angielski
Score (nominal)35
Score sourcejournalList
ScoreMinisterial score = 35.0, 27-05-2020, ArticleFromJournal
Publication indicators WoS Citations = 0; Scopus SNIP (Source Normalised Impact per Paper): 2017 = 0.886; WoS Impact Factor: 2014 = 2.808 (2) - 2014=2.628 (5)
Citation count*1 (2020-05-29)
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