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Subexponential Decay of Local Correlations from Diffusion-Limited Dephasing.
Ewan McCulloch1, J Alexander Jacoby2, Curt von Keyserlingk3
1Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08544, USA.
Physical Review Letters
|May 29, 2026
Summary
In one-dimensional chaotic quantum systems, dephasing of quantum superpositions is surprisingly slow, decaying subexponentially. Rare low-entropy regions protect quantum coherence, a phenomenon beyond standard hydrodynamics.
Area of Science:
- Quantum physics
- Condensed matter theory
- Statistical mechanics
Background:
- Chaotic quantum systems typically act as heat baths, causing rapid dephasing.
- This rapid dephasing is expected to destroy local quantum superpositions.
Purpose of the Study:
- To investigate the dephasing dynamics in one-dimensional chaotic quantum systems with conservation laws.
- To determine if dephasing is always rapid or if alternative mechanisms exist.
Main Methods:
- Theoretical analysis of local correlation functions in 1D systems.
- Consideration of systems with conservation laws and orthogonal operators.
- Investigation of diffusion-limited dephasing mechanisms.
Main Results:
- Local correlation functions decay subexponentially (exp[-O(t^{α})], 0≤α≤2/3), not exponentially.
- Rare low-entropy regions act as "voids" that protect quantum coherences.
- Specific values found: α=1/2 in random charge-conserving circuits, α≤2/3 in Floquet systems.
Conclusions:
- Dephasing in 1D chaotic systems with conservation laws is generically subexponential.
- Diffusion-limited dephasing, driven by low-entropy regions, is a key mechanism.
- This quantum effect is distinct from standard hydrodynamics and extrinsic dephasing.
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