Spontaneous emission is a phenomenon where an excited atom or quantum system transitions to a lower energy state by emitting a photon. It is considered to be a fundamentally quantum mechanical process that arises due to quantum fluctuations.
The connection between spontaneous emission and quantum fluctuations can be understood through the concept of vacuum fluctuations. According to quantum field theory, even in the absence of any external electromagnetic fields, the vacuum of empty space is not completely empty. It is filled with virtual particles that continuously pop in and out of existence, including virtual photons. These vacuum fluctuations can influence the behavior of atoms and lead to spontaneous emission.
The verification of the role of quantum fluctuations in spontaneous emission is primarily done through experimental observations and theoretical calculations. Quantum electrodynamics (QED), which is the quantum field theory describing the interactions between electrons, photons, and atoms, provides a theoretical framework to analyze and predict the properties of spontaneous emission.
As for isolating atoms in their existing states from external influences such as phonons and photons, it can be challenging but not impossible. Various experimental techniques are employed to achieve such isolation. Here are a few methods:
Ultracold atom techniques: By using laser cooling and trapping techniques, atoms can be cooled to extremely low temperatures, reducing their thermal motion and interaction with phonons.
Optical cavities: Placing atoms inside high-quality optical cavities can suppress interactions with external photons and modify the spontaneous emission process. The cavity can enhance or suppress certain emission modes and influence the emitted photons' properties.
Vacuum chambers: Isolating the atoms in vacuum chambers can minimize interactions with external particles and fields, reducing the influence of phonons and photons.
Shielding: Physical shielding, such as using materials with high atomic number or electromagnetic shielding, can reduce external electromagnetic fields and prevent unwanted interactions.
While complete isolation from all external influences is challenging, experimental techniques can be employed to minimize their effects and create controlled environments where the behavior of atoms and their emissions can be studied with high precision.
It's important to note that achieving perfect isolation is not always necessary to study spontaneous emission and its connection to quantum fluctuations. By carefully characterizing and controlling the external influences, scientists can study the fundamental aspects of spontaneous emission and its relation to quantum fluctuations.