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Related Experiment Video

Updated: Oct 9, 2025

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators

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Published on: May 30, 2014

Randomness and Irreversiblity in Quantum Mechanics: A Worked Example for a Statistical Theory.

Yves Pomeau¹, Martine Le Berre¹

¹Laboratoire d'Hydrodynamique, Ladhyx, CNRS UMR 7646, Ecole Polytechnique, 91128 Palaiseau, France.

Entropy (Basel, Switzerland)

|December 24, 2021

Summary

This study introduces a new method to understand quantum jumps in two-level atoms by assigning probability to the density matrix. This approach models the atom's statistical properties, offering insights into quantum randomness and information loss.

Keywords:

Everett’s interpretation Kolmogorov-like model fluorescence irreversibility quantum jumps

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Last Updated: Oct 9, 2025

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Published on: September 5, 2019

Area of Science:

Quantum Mechanics
Atomic Physics
Statistical Mechanics

Background:

Irreversible quantum phenomena present challenges in understanding randomness and information loss due to broken quantum coherence.
The fluorescence of a single two-level atom under laser illumination exemplifies these difficulties, as deterministic equations conflict with observed random quantum jumps.
Existing models struggle to reconcile the coherent Rabi oscillations of the atom with the instantaneous, decoherent photon emissions.

Purpose of the Study:

To present a novel, completed approach for describing quantum jumps in a two-level atom system.
To develop a probabilistic framework for the atom's density matrix to address quantum randomness.
To derive a kinetic equation governing the probability distribution of the atom's state over time.

Main Methods:

Proposed a novel approach involving assigning probability to the atom's density matrix.
Derived a general "kinetic Kolmogorov-like" equation for the evolution of this probability.
Analyzed the probability distribution p(θ,t) dependent on the atomic state variable θ and time t.

Main Results:

The derived kinetic equation successfully describes the statistical properties of the two-level atom.
The probability distribution p(θ,t) captures the system's behavior under coherent pumping and random photon emission.
The approach allows for the description of all possible histories of the atom, akin to the many-worlds interpretation.

Conclusions:

The novel probabilistic approach provides a solvable framework for understanding quantum jumps in two-level atoms.
This method offers a new perspective on reconciling deterministic quantum evolution with irreversible, random phenomena.
The framework potentially bridges statistical interpretations of quantum mechanics with concepts like Everett's many-worlds interpretation.