Particle creation in a time-dependent electric field revisited

摘要

We adopt the general formalism for analyzing evolution ofgaussian states of quantized fields in time-dependent backgrounds in the Schrodinger picture (presented in detail in Mahajan and Padmanab-han G. Mahajan, T. Padmanabhan, Gen. Rel. Gray. 40 (2008) 661) to study the example of a spatially uniform electric field background (in a time-dependent gauge) which is kept turned on for a finite duration of time. In particular, we study the time-dependent parti_cle content, defined in terms of the concept of instantaneous eigen-states, and describe how it captures the time evolution of the quantized field modes. The actual particle creation process occurs over a relatively short interval in time, and the particle content sat-urates rather quickly. We also compare the power spectrum of the field modes, computed in the asymptotic limit, with the corre-sponding situation in a cosmological de Sitter background. Particle creation under the influence of a spiked electric field localized in time, as a particular limiting case of the above general model, is also considered.