Interference in Complex Canonical Variables Is Not Quantum

Quantum Reports MDPI 7:3 (2025) 40

Authors:

Chiara Marletto, Vlatko Vedral

Abstract:

We formally represent the quantum interference of a single qubit embodied by a photon in the Mach–Zehnder interferometer using the classical Hamiltonian framework but with complex canonical variables. Although all operations on a single qubit can be formally expressed using complex classical Hamiltonian dynamics, we show that the resulting system is still not a proper qubit. The reason for this is that it is not capable of getting entangled to another bona fide qubit and hence it does not have the information-processing capacity of a fully-fledged quantum system. This simple example powerfully illustrates the difficulties faced by hybrid quantum–classical models in accounting for the full range of behaviour of quantum systems.

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Physical Review A American Physical Society (APS) 112:2 (2025) 022428

Authors:

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Authors:

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Authors:

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