Understanding Photon Absorption and Retransmission in Quantum Mechanics

The behavior of photons as they interact with matter is a fascinating aspect of quantum mechanics. Photons, which are packets of light, can either be absorbed by an object or re-emitted after interaction with an electron. This article delves into the mechanisms of photon absorption and re-emission, drawing on fluid mechanics analogies and theoretical concepts from quantum mechanics.

Basic Mechanism of Photon Absorption

Photons interact with matter primarily through absorption. When a photon encounters an electron in a medium, it can be absorbed if the energy difference between the electron’s next available higher energy state and its current state matches the photon’s energy (Planck constant x photon’s frequency). This energy transition leads the electron to move from its current state to the next available higher state.

The Electron's Response

After absorption, the electron may return to a lower energy state by re-emitting a photon. This re-emitted photon has an energy equal to the difference between the electron’s current and new lower energy states. This process involves the electron emitting a photon equivalent to the energy difference, effectively lowering its energy back to the original state or a lower energy state.

Quantum Mechanical Analogy: Photons as Wind and Electrons as Hurricanes

To better illustrate the process, consider a fluid mechanics analogy. Imagine photons as wind and electrons as hurricanes. If a strong wind encounters a hurricane, it can either make the hurricane stronger, cause it to dissipate, or even re-emerge in another form. However, just as wind interacting with a hurricane doesn’t mean that the same wind re-emerges, photon absorption and re-emission must be viewed with caution.

The Role of Quantum Properties

Unlike the fluid mechanics analogy, quantum mechanics introduces intrinsic properties that can help identify if a re-emitted photon is the same one that was absorbed. For instance, in the case of entangled particles, if one photon is absorbed and another re-emitted, a scientific measurement can reveal if the new photon is entangled with the original. If it is, it’s considered the same photon re-emitted. If not, it’s a new photon.

The Photon Paradox: Same or Different?

Consider an example where a photon interacts with an electron, causing the electron to move to a higher energy state. When the electron re-emits a photon, you can only determine if it’s the same photon through measurement. Similarly, a wind carrying balloons into a hurricane might carry the same balloons back out, making it reasonable to assume it’s the same wind.

Conclusion

In the intricate world of quantum mechanics, the behavior of photons is governed by complex yet predictable rules. While photons can be re-emitted in various forms, the criteria for identifying the same photon in different interactions provide valuable insights into the mechanisms of energy transfer at the quantum level. Understanding these phenomena is crucial for advancements in fields like quantum computing, photonics, and beyond.

For a deeper understanding, you might like to read pages 10 to 21 on the Photoelectric Effect in TIFR booklet on Einstein. This resource provides a comprehensive overview of the underlying principles and real-world applications.

References

TIFR booklet on Einstein: Photoelectric Effect