Collapse Dynamics Are Diffusive

Area of Science:

• Quantum Mechanics
• Foundations of Physics

Background:

• Spontaneous wave function collapse models predict deviations from quantum superposition for large systems.
• Noninterferometric experiments have previously constrained collapse models by detecting noise-induced diffusive motion.

Purpose of the Study:

• To demonstrate that any spatial wave function collapse dynamics, not just noisy ones, must exhibit diffusive properties.
• To broaden the applicability of noninterferometric experiments to a wider range of collapse models.

Main Methods:

• Theoretical analysis of collapse dynamics under reasonable assumptions.
• Mathematical proof based on space-translation covariance and the no-signaling constraint.

Main Results:

• Any spatial wave function collapse dynamics is shown to be inherently diffusive.
• Collapse models must alter the average momentum and/or its spread of a quantum system.

Conclusions:

• The noninterferometric approach is broadly applicable to testing spatial wave function collapse models.
• This work provides a theoretical foundation for designing new experiments to probe fundamental quantum mechanics.