Are absorption and spontaneous or stimulated emission inverse processes? The answer is subtle!

Area of Science:

• Quantum optics
• Atomic physics
• Electromagnetism

Background:

• Absorption and stimulated emission are traditionally considered inverse processes governed by the Einstein B coefficient.
• Spontaneous emission is thought to occur with an arbitrary phase relative to an incident field.
• Recent findings suggest a deviation from the conventional understanding of phase relationships in emission and absorption.

Purpose of the Study:

• To rigorously verify the phase relationship between absorption and emission processes.
• To clarify the precise nature of the inverse relationship between absorption and spontaneous emission.
• To investigate the phase dynamics using amplitude-phase diagrams and wave interference.

Main Methods:

• Utilizing amplitude-phase diagrams to visualize and analyze the processes.
• Employing the interference of sine waves to examine phase relationships.
• Analyzing photon number changes during absorption (φ+1 to φ) and emission (φ to φ+1).

Main Results:

• Absorption and emission are confirmed as truly inverse processes, including their phase relationship.
• The study demonstrates that absorption of one photon and spontaneous emission into an empty mode are inverse processes in the amplitude-phase diagram.
• Deviations from the traditional view of phase relations in stimulated emission are highlighted.

Conclusions:

• Absorption and spontaneous emission are precisely inverse processes in both amplitude and phase.
• The findings necessitate a refinement of the understanding of light-matter interactions.
• This work provides a more accurate theoretical framework for quantum optical phenomena.