TY - CHAP
T1 - The photon: A virtual reality
AU - Andrews, D. L.
N1 - Conference on Nature of Light - What is a Photon AUG 01-02, 2005 San Diego, CA
PY - 2005
Y1 - 2005
N2 - It has been observed that every photon is, in a sense, virtual - being emitted and then sooner or later absorbed. As the motif of a quantum radiation state, the photon shares these characteristics of any virtual state: that it is not directly observable; and that it can signify only one of a number of indeterminable intermediates, between matter states that are directly measurable. Nonetheless, other traits of real and virtual behavior are usually quite clearly differentiable. How 'real', then, is the photon? To address this and related questions it is helpful to look in detail at the quantum description of light emission and absorption. A straightforward analysis of the dynamic electric field, based on quantum electrodynamics, reveals not only the entanglement of energy transfer mechanisms usually regarded as 'radiative' and 'radiation less'; it also gives significant physical insights into several other electromagnetic topics. These include: the propagating and non-propagating character in electromagnetic fields; near-zone and wave-zone effects; transverse and longitudinal character; the effects of retardation, manifestations of quantum uncertainty and issues of photon spin. As a result it is possible to gain a clearer perspective on when, or whether, the terms 'real' and 'virtual' are helpful descriptors of the photon.
AB - It has been observed that every photon is, in a sense, virtual - being emitted and then sooner or later absorbed. As the motif of a quantum radiation state, the photon shares these characteristics of any virtual state: that it is not directly observable; and that it can signify only one of a number of indeterminable intermediates, between matter states that are directly measurable. Nonetheless, other traits of real and virtual behavior are usually quite clearly differentiable. How 'real', then, is the photon? To address this and related questions it is helpful to look in detail at the quantum description of light emission and absorption. A straightforward analysis of the dynamic electric field, based on quantum electrodynamics, reveals not only the entanglement of energy transfer mechanisms usually regarded as 'radiative' and 'radiation less'; it also gives significant physical insights into several other electromagnetic topics. These include: the propagating and non-propagating character in electromagnetic fields; near-zone and wave-zone effects; transverse and longitudinal character; the effects of retardation, manifestations of quantum uncertainty and issues of photon spin. As a result it is possible to gain a clearer perspective on when, or whether, the terms 'real' and 'virtual' are helpful descriptors of the photon.
M3 - Chapter
SN - 0277-786X 0-8194-5871-6
VL - 5866
T3 - Proceedings of the Society of Photo-Optical Instrumentation Engineers (Spie)
SP - 1
EP - 7
BT - Nature of Light: What is a Photon?
A2 - Roychoudhuri, C.
A2 - Creath, K.
A2 - Kracklauer, A. L. F.
PB - CRC Press
ER -