Quantum electrodynamics spontaneous photon emission

Abstract Rapid advances in quantum technology have made possible the control of quantum states of elementary material quantum systems, such as atoms or molecules, and of the electromagnetic radiation field resulting from spontaneous photon emission of their unstable excited states to such a level of precision that subtle quantum electrodynamical phenomena have become observable experimentally. Recent developments in the area of quantum information processing demonstrate that characteristic quantum electrodynamical effects can even be exploited for practical purposes provided the relevant electromagnetic field modes are controlled by appropriate cavities. A central problem in this context is the realization of an ideal transfer of quantum information between a state of a material quantum system and a quantum... 

Another example of zero-point energy arises in the detailed quantum theory of the electromagnetic field, known as quantum electrodynamics. The empty vacuum with no photons present is actually the zero-point level with n = 0. The non-zero energy of this state cannot be measured directly, but does have some observable consequences. The vacuum is really a state of fluctuating electric and magnetic fields that are significant at the atomic level. Without them, there would be no mechanism for the spontaneous emission of photons from excited states. There also have very small effects on the energy levels of atoms (see Section 4.4). 

The Purcell s original idea [10] on modification of photon spontaneous emission rate is extended to modification of photon spontaneous scattering rate. Simultaneous account for local incident field and local density of photon states enhancements in close proximity to a silver nanoparticle is found to provide up to lO -fold Raman scattering cross-section rise up. Thus, single molecule Raman detection is found to be explained by consistent quantum electrodynamic description without chemical mechanisms involved. 

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