Quantum Interference Paradox

F. J. Duarte

Ever since Schrödinger envisioned the possibility of quantum entanglement, in 1935, by contemplating the implications of the meaning of ‘not complete’ emitted by Einstein and colleagues towards quantum mechanics the word paradox has been brought forth. Paradox was again invoked by Bohm in the 1950s and of course the creation of Bell's theorem was motivated by it. Paradox has been a trademark of the philosophical path towards quantum entanglement. And yet, the physics tells us that quantum entanglement is not afflicted at all by any paradox whatsoever. That this was the case was first silently implied by the physics of Dirac, Wheeler, and Pryce and Ward (1930–1947) and directly articulated by Feynman in 1965. Here we transparently show that, from the quantum interference perspective, the physics of quantum entanglement is completely and utterly free of paradoxes.

Ivars Peterson

Robert B. Griffiths

Michael Martin Nieto

Using the vehicle of resolving an apparent paradox, a discussion of quantum interference is presented. The understanding of a number of different physical phenomena can be unified, in this context. These range from the neutral kaon system to massive neutrinos, not to mention quantum beats, Rydberg wave packets, and neutron gravity.

David Thomas Pegg

The retrocausality inherent in the retrodictive description of a quantum optical device called the quantum scissors allows this device to be used as a non-deterministic time machine. We show how the device can be used to model the time travel paradox of retrospective suicide. Here a man goes back in time and interferes with his own birth, weakening his infant self in such a way that he is killed by the time machine and is unable to interfere with his own birth. We find that the paradox is avoided by interfering quantum mechanical amplitudes making the time travel event impossible in this case. A slight modification that limits the interference with the birth so that the infant is only injured by the time machine to give a self-consistent cycle does, however, render the time travel event possible. This lends support to the idea that time travel is only possible if it yields a self-consistent cycle that avoids a paradox.