On the Feynman Problem

Jayant Vishnu Narlikar

S. Balasubramanian

Lev Sakhnovich

In this note, we formulate the notions of the direct and inverse problems and contact points for the Feynman diagrams. For the electron-photon interaction case, the solutions of these direct and inverse problems are presented. The interrelations between Feynman diagrams and the classical colored graphs are discussed.

Giacomo Mauro D’Ariano, Franco Manessi, Paolo Perinotti +1 more

The present paper is both a review on the Feynman problem, and an original research presentation on the relations between Fermionic theories and qubits theories, both regarded in the novel framework of operational probabilistic theories. The most relevant results about the Feynman problem of simulating Fermions with qubits are reviewed, and in the light of the new original results, the problem is solved. The answer is twofold. On the computational side, the two theories are equivalent, as shown by Bravyi and Kitaev [S. B. Bravyi and A. Y. Kitaev, Ann. Phys. 298, 210 (2002)]. On the operational side, the quantum theory of qubits and the quantum theory of Fermions are different, mostly in the notion of locality, with striking consequences on entanglement. Thus the emulation does not respect locality, as it was suspected by Feynman [R. Feynman, Int. J. Theor. Phys. 21, 467 (1982)].

Marlan O. Scully, HERBERT WALTHER, Wolfgang P. Schleich

Feynman introduces the concept of negative probability in the context of Young's double-slit experiment and in doing so sheds a new light on the problem. However, there are, as Feynman notes, conceptual problems as well as insights associated with this point of view. The micromaser which-path (Welcher-Weg) detector eliminates these conceptual difficulties. We also emphasize that the concept of negative probability yields useful insight into the Einstein-Podolsky-Rosen (EPR) problem.