# A First Principles Numerical Demonstration of Emergent Decoherent Histories

**Authors:** Philipp Strasberg, Teresa E. Reinhard, Joseph Schindler  
**arXiv:** [2304.10258](https://arxiv.org/abs/2304.10258)  
**Date:** 2023-04-20  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2304.10258v3/

## Key points

- Authors: Philipp Strasberg, Teresa E. Reinhard, Joseph Schindler
- Investigate classicality emergence in isolated quantum systems using histories formalism and decoherence functional
- Conduct thorough evaluation for up to five-time histories through exact numerical diagonalization of the Schrödinger equation
- Robust emergence of decoherence observed for slow and coarse observables within a generic random matrix model
- Varying Hilbert space dimension over four orders of magnitude reveals finite size scaling law related to coherent effects and particle number behavior
- Exponential suppression suggests potential solution to preferred basis problem in interpretations like many worlds or set selection within histories formalism
- Findings offer valuable insights without relying on environmentally induced decoherence, quantum Darwinism, Markov approximations, low-entropy initial states, or ensemble averages
- Contributes to advancing understanding of classicality emergence in quantum systems and provides minimal theoretical framework for addressing fundamental questions in quantum mechanics

## Summary

In their paper titled "A First Principles Numerical Demonstration of Emergent Decoherent Histories," authors Philipp Strasberg, Teresa E. Reinhard, and Joseph Schindler delve into the investigation of classicality emergence in isolated quantum systems using the histories formalism and the decoherence functional. The significance of this formal tool is highlighted as the authors conduct a thorough evaluation for up to five-time histories through exact numerical diagonalization of the Schr\"odinger equation. Their study reveals a robust emergence of decoherence for slow and coarse observables within a generic random matrix model. By varying the Hilbert space dimension over four orders of magnitude, they extract a finite size scaling law that sheds light on the behavior of coherent effects as a function of the particle number in the system. This exponential suppression suggests a potential solution to the preferred basis problem associated with interpretations like many worlds or set selection within the histories formalism. The findings presented in this research provide valuable insights without relying on environmentally induced decoherence, quantum Darwinism, Markov approximations, low-entropy initial states, or ensemble averages. This work contributes to advancing our understanding of how classicality emerges in quantum systems and offers a minimal theoretical framework for addressing fundamental questions in quantum mechanics.