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Intrinsic Generation of Angular Momenta and Entanglement in Fission
B Li1, D D Zhang2, D Vretenar1,3
1Peking University, State Key Laboratory of Nuclear Physics and Technology, School of Physics, Beijing 100871, China.
Physical Review Letters
|July 10, 2026
Summary
Nuclear fission spin entanglement is explored using time-dependent density functional theory. Breaking axial symmetry in nuclear fission impacts fragment spin correlations, affecting collective rotations and entanglement.
Area of Science:
- Nuclear Physics
- Quantum Mechanics
Background:
- Spontaneous fission of Californium-252 (²⁵²Cf) is a key nuclear process.
- Understanding fission fragment spin generation and entanglement is crucial for nuclear structure and reaction dynamics.
Purpose of the Study:
- Investigate spin generation and entanglement of fission fragments in ²⁵²Cf spontaneous fission.
- Examine the influence of axial and nonaxial deformations on fragment spin dynamics.
Main Methods:
- Utilized nuclear time-dependent density functional theory (TDDFT).
- Incorporated both axial and nonaxial deformations in fission trajectory calculations.
- Applied mutual information analysis to quantify spin correlations.
Main Results:
- Axially symmetric trajectories impose constraints on fragment spins (counterrotation, bending, wriggling).
- Nonaxial modes broaden spin projection distributions and enable forbidden axial rotations.
- Breaking axial symmetry reduces spin-spin correlations along the fission axis but preserves perpendicular correlations.
Conclusions:
- Nonaxial deformations significantly influence fission fragment spin dynamics and entanglement.
- Axial symmetry breaking plays a critical role in determining the nature of spin correlations.
- Further analysis of triaxial degrees of freedom is needed to understand spin opening angles.
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