Density matrix in quantum electrodynamics, equivalence principle and Hawking effect
Abstract
The expression for the density matrix describing particles of one sort (electrons or positrons) created by an external electromagnetic field from the vacuum is obtained. The explicit form of the density matrix is found for the case of constant and uniform electric field. Arguments are given for the presence of a connection between the thermal nature of the density matrix describing particles created by the gravitational field of a black hole and the equivalence principle.
 Publication:

Journal of Physics A Mathematical General
 Pub Date:
 July 1978
 DOI:
 10.1088/03054470/11/7/019
 Bibcode:
 1978JPhA...11.1329F
 Keywords:

 Black Holes (Astronomy);
 Electron Density (Concentration);
 Gravitational Effects;
 Particle Production;
 Quantum Electrodynamics;
 Space Density;
 Electric Fields;
 Electromagnetic Fields;
 Equivalence;
 Matrices (Mathematics);
 Positrons;
 Thermal Radiation;
 Astrophysics