On the Theory of Photon‐Assisted Zener Tunneling

Abstract

Zener tunneling assisted by one-photon absorption is studied theoretically. A general expression for the transition rate is obtained and further evaluated for both a two-band and a three-band process, where analytical results are presented in terms of Airy functions. Furthermore, an interband current is produced by photon assisted tunneling which is shown to be proportional to the corresponding transition rate. It can be concluded from these results that photon assisted tunneling noticeably contributes to macroscopically observable quantities like electroabsorption and electric current, especially, if two nearly degenerate valence or conduction bands exist. I n the latter case an interband current is produced flowing opposite to the field direction.Es wird Zenertunneln, welches von Ein-Photon-Absorption begleitet ist, untersucht. Ausgehend von einem allgemeinen Ausdruck

Exact property of the nonequilibrium photon Green function for bounded media

“…Note also, that according to Eq. (20), the vacuum spectral function (24) is, as it should be, always conserved independently of the choice of D > 0,stim (1, 2) = D < 0,stim (1,2). Using Eq.…”

“…These two kinds of field-field fluctuations were shown to enter the physics of absorption and emission in a completely different way. 1,2 In the steady-state slab geometry, namely, the vacuum-induced contributions alone determine absorption and emission, while medium-induced contributions completely cancel out. Here, no restrictions or assumptions were made, so this splitting appears naturally as an universal property of the photon GF, and is valid for arbitrarily nonstationary excited media with any geometry.…”

“…Whereas the spectral function (24) of the vacuum is fixed, its kinetical state (or population of modes) is still to be specified corresponding to the (external) preparation of the outside region. One may thus assume, quite generally, an arbitrary field-field fluctuation D ≷ 0,stim (1,2) in the vacuum or free space. It is, hence, externally stimulated by preparation and will add to a spontaneous contribution from the ground state fluctuations of the electromagnetic vacuum, D ≷ 0,sp , such that the complete fluctuations in the vacuum can be written as…”

“…Recently, we were able to present a general, exact law for the electromagnetic energy flow between a medium and the surrounding vacuum. 1,2 The dynamical and spatially inhomogeneous coupled system of matter and light was described in a quantum-kinetically consistent way by photon Green functions, i.e., Green functions (GFs) defined in terms of the electromagnetic vector potential, and the nonequilibrium Keldysh technique (see Ref. 2 for a short introduction to these topics).…”