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Paths, negative "probabilities", and the Leggett-Garg inequalities
D Sokolovski1,2, S A Gurvitz3
1Departmento de Química-Física, Universidad del País Vasco, UPV/EHU, Leioa, Spain. dgsokol15@gmail.com.
Scientific Reports
|May 10, 2019
Summary
Previous observations can influence future measurements through "signalling in time" when they destroy quantum interference. Feynman's negative probabilities offer a more reliable detection method than Leggett-Garg inequalities, though both can fail.
Area of Science:
- Quantum mechanics
- Foundations of physics
Background:
- The influence of past observations on future measurements is a subtle quantum phenomenon.
- Understanding this effect is crucial for interpreting quantum experiments and theories.
Purpose of the Study:
- To analyze the conditions leading to "signalling in time".
- To compare the effectiveness of different methods for detecting this phenomenon.
Main Methods:
- Path analysis of quantum measurement outcomes.
- Investigated the role of interference destruction in signalling.
- Compared Feynman's negative probabilities with Leggett-Garg inequalities.
Main Results:
- Signalling in time occurs when measurements destroy interference between virtual paths.
- Feynman's negative probabilities are a more robust indicator of signalling in time than Leggett-Garg inequalities.
- Both detection methods are prone to failure under certain conditions.
Conclusions:
- The study clarifies the conditions for "signalling in time" in quantum mechanics.
- Highlights the utility and limitations of Feynman's negative probabilities and Leggett-Garg inequalities for detecting this effect.
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