On the Locality in Quantum-Mechanical Processes

We analyze the quantum process tomography (QPT) in the presence of decoherence, focusing on distinguishing local and nonlocal decoherence mechanisms for a two-partite system from experimental QPT data. In particular, we consider the $\sqrt{i\text{SWAP}}$ gate realized with superconducting phase qubits and calculate the QPT matrix $\ensuremath{\chi}$ in the presence of several local and nonlocal decoherence processes. We determine specific patterns of these decoherence processes, which can be used for a fast identification of the main decoherence mechanisms from an experimental $\ensuremath{\chi}$ matrix.We analyze the quantum process tomography (QPT) in the presence of decoherence, focusing on distinguishing local and nonlocal decoherence mechanisms for a two-partite system from experimental QPT data. In particular, we consider the $\sqrt{i\text{SWAP}}$ gate realized with superconducting phase qubits and calculate the QPT matrix $\ensuremath{\chi}$ in the presence of several local and nonlocal decoherence processes. We determine specific patterns of these decoherence processes, which can be used for a fast identification of the main decoherence mechanisms from an experimental $\ensuremath{\chi}$ matrix.

arXiv:0903.0671Physical Review AOct 5, 200936 citations

Time as the Hidden Variable of Quantum Mechanics: An LTST Interpretation.

Dmitriy Kim

Time as the Hidden Variable of Quantum Mechanics: An LTST Interpretation Description This preprint presents an interpretive framework for quantum mechanics from the standpoint of LTST — Local Time Synchronization Theory. The central idea is that quantum uncertainty may arise not from an intrinsic randomness of nature, but from a mismatch between the observer’s external time scale and the local time of the physical process itself. The work does not reject the mathematical formalism of quantum mechanics. Instead, it proposes a different ontological reading of its core concepts. In this interpretation, the wave function is understood as a space of possible local-temporal synchronizations, superposition as incomplete synchronization, collapse as the fixation of one admissible configuration, and quantum instantaneity as the compression of a process’s internal local duration into a single manifested event on the observer’s time ruler. The preprint also introduces a correspondence table between standard quantum-mechanical concepts and their LTST interpretation, and outlines possible directions for testable consequences, including the role of measurement apparatus as an active observation mask and the search for pre-collapse synchronization structures. Abstract Quantum mechanics is an exceptionally successful computational framework, yet its interpretation remains tied to an external time parameter associated with the observer, laboratory frame, or measuring apparatus. This preprint proposes an LTST interpretation in which quantum uncertainty is understood as a symptom of mismatch between the observer’s time ruler and the local time of the process itself. From this perspective, a physical event does not occur merely because external time has passed. It appears when local times enter a compatible synchronization regime. The wave function is interpreted as a space of possible local-temporal synchronizations; superposition corresponds to incomplete synchronization; collapse is the fixation of an admissible configuration; and quantum instantaneity is not necessarily the true instantaneity of the process, but the observer’s lack of access to the process’s internal local duration. The proposed interpretation does not invalidate the mathematical apparatus of quantum mechanics. Rather, it changes its ontological status: quantum mechanics is treated as an effective description of processes whose local time is not directly revealed in the observer’s temporal scale. LTST therefore reframes quantum uncertainty as a projection effect caused by mismatched temporal architectures, rather than as final evidence of fundamental randomness in nature. Keywords LTST; local time; quantum mechanics; temporal uncertainty; wave function collapse; superposition; observer; measurement problem; hidden variable; local-temporal synchronizationTime as the Hidden Variable of Quantum Mechanics: An LTST Interpretation Description This preprint presents an interpretive framework for quantum mechanics from the standpoint of LTST — Local Time Synchronization Theory. The central idea is that quantum uncertainty may arise not from an intrinsic randomness of nature, but from a mismatch between the observer’s external time scale and the local time of the physical process itself. The work does not reject the mathematical formalism of quantum mechanics. Instead, it proposes a different ontological reading of its core concepts. In this interpretation, the wave function is understood as a space of possible local-temporal synchronizations, superposition as incomplete synchronization, collapse as the fixation of one admissible configuration, and quantum instantaneity as the compression of a process’s internal local duration into a single manifested event on the observer’s time ruler. The preprint also introduces a correspondence table between standard quantum-mechanical concepts and their LTST interpretation, and outlines possible directions for testable consequences, including the role of measurement apparatus as an active observation mask and the search for pre-collapse synchronization structures. Abstract Quantum mechanics is an exceptionally successful computational framework, yet its interpretation remains tied to an external time parameter associated with the observer, laboratory frame, or measuring apparatus. This preprint proposes an LTST interpretation in which quantum uncertainty is understood as a symptom of mismatch between the observer’s time ruler and the local time of the process itself. From this perspective, a physical event does not occur merely because external time has passed. It appears when local times enter a compatible synchronization regime. The wave function is interpreted as a space of possible local-temporal synchronizations; superposition corresponds to incomplete synchronization; collapse is the fixation of an admissible configuration; and quantum instantaneity is not necessarily the true instantaneity of the process, but the observer’s lack of access to the process’s internal local duration. The proposed interpretation does not invalidate the mathematical apparatus of quantum mechanics. Rather, it changes its ontological status: quantum mechanics is treated as an effective description of processes whose local time is not directly revealed in the observer’s temporal scale. LTST therefore reframes quantum uncertainty as a projection effect caused by mismatched temporal architectures, rather than as final evidence of fundamental randomness in nature. Keywords LTST; local time; quantum mechanics; temporal uncertainty; wave function collapse; superposition; observer; measurement problem; hidden variable; local-temporal synchronization

Jun 25, 20260 citations

Locality problem in quantum theory

D. A. Slavnov

arXiv:0903.4013Theoretical and Mathematical PhysicsMay 1, 20088 citations

Locality in Quantum Theory

Travis Norsen

Elsevier eBooksJan 1, 20260 citations

Branching (Almost) Everywhere And All at Once

Alyssa Ney

It is sometimes said that a reason to prefer Everettian quantum mechanics is that it allows one to avoid the kind of spooky action at a distance that is a consequence of quantum entanglement according to other approaches. There is a straightforward argument to show EQM has this virtue, however some advocates argue that this requires we see branching as a local causal process. I explain this reasoning and then show why, given the way Everettians standardly conceive of worlds and branching as emergent phenomena, branching need not be viewed as a causal process for EQM to be relativistically local. Forthcoming in Local Quantum Mechanics, OUP 2026.It is sometimes said that a reason to prefer Everettian quantum mechanics is that it allows one to avoid the kind of spooky action at a distance that is a consequence of quantum entanglement according to other approaches. There is a straightforward argument to show EQM has this virtue, however some advocates argue that this requires we see branching as a local causal process. I explain this reasoning and then show why, given the way Everettians standardly conceive of worlds and branching as emergent phenomena, branching need not be viewed as a causal process for EQM to be relativistically local. Forthcoming in Local Quantum Mechanics, OUP 2026.

quant-pharXiv:2608.18644Aug 20, 2026

\sqrt{i\text{SWAP}}

gate realized with superconducting phase qubits and calculate the QPT matrix $\ensuremath{\chi}$ in the presence of several local and nonlocal decoherence processes. We determine specific patterns of these decoherence processes, which can be used for a fast identification of the main decoherence mechanisms from an experimental $\ensuremath{\chi}$ matrix.