2018/05/31 by Anastasia Korolov, L. H. Ford
Chemistry · Computer Science · Mathematics · Physics and Astronomy · #Chemistry #Computer science #Electric field #Excited state #Field (mathematics) #Geometry #Limit (mathematics) #Mathematical analysis #Mathematics #Mean field theory #Mean squared error #Mean value #Measure (data warehouse) #Operator (biology) #Photon #Physics #Quantum Electrodynamics and Casimir Effect #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum mechanics #Square (algebra) #Statistics #Upper and lower bounds #gr-qc #hep-th #quant-ph
paper · pdf · doi:10.1103/physrevd.98.036020
published as Phys. Rev. D 98, 036020 (2018) · 17 pages, 3 figures; expanded version, with more discussion and a new section on the physical interpretation of the results
openalex publication_date 2018/08/28 · arxiv created 2018/09/07 · arxiv updated 2018/09/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We discuss an example of a subvacuum effect, where a quantum expectation value is below the vacuum level, and is hence negative. The example is the time average of the mean squared electric field in a nonclassical state where one mode is excited. We give some specific examples of such states, and discuss the lower bound on the squared field or its time average. We show when a lower bound can be obtained by diagonalization of the squared electric field operator, and calculate this bound. We also discuss the case of an instant time mean squared electric field, when the operator cannot be diagonalized. In this case, a lower bound still exists but is attained only by the limit of a sequence of quantum states. In general, the optimum lower bound on the mean squared electric field is minus one-half of the mean squared electric field in a one-photon state. This provides a convenient estimate of the subvacuum effect, and may be useful for attempts to experimentally measure this effect.