Complex-Valued Classical Behavior from the Correspondence Limit of Quantum Mechanics with Two Boundary Conditions

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The two-state-vector formalism presents a time-symmetric approach to the standard quantum mechanics, with particular importance in the description of experiments having pre- and post-selected ensembles. In this paper, using the correspondence limit of the quantum harmonic oscillator in the two-state-vector formalism, we produce harmonic oscillators that possess a classical behavior while having a complex-valued position and momentum. This allows us to discover novel effects that cannot be achieved otherwise. The proposed classical behavior does not describe the classical physics in the usual sense since this behavior is subjected to the feature that only after the final measurement is performed, as a boundary condition, the complex-valued classical effects occur between the initial and the final boundary conditions. This classical behavior breaks down if one does not follow the decided boundary conditions during the experiment, since otherwise, one will contradict the impossibility of retrocausality.


This article was originally published in Foundations of Physics, volume 52, in 2022. https://doi.org/10.1007/s10701-022-00576-8