Dynamical Coulomb blockade theory of plasmon-mediated light emission from a tunnel junction

Abstract

Inelastic tunneling of electrons can generate the emission of photons with energies intuitively limited by the applied bias voltage. However, experiments indicate that more complex processes involving the interaction of electrons with plasmon polaritons lead to photon emission with overbias energies. We recently proposed a model of this observation in Phys. Rev. Lett. 113, 066801 (2014), in analogy to the dynamical Coulomb blockade, originally developed for treating the electromagnetic environment in mesoscopic circuits. This model describes the correlated tunneling of two electrons interacting with a local plasmon-polariton mode, represented by a resonant circuit, and shows that the overbias emission is due to the non-Gaussian fluctuations. Here we extend our model to study the overbias emission at finite temperature. We find that the thermal smearing strongly masks the overbias emission. Hence, the detection of the correlated tunneling processes requires temperatures kBT much lower than the bias energy eV and the plasmon energy ω0, a condition which is fortunately realized experimentally.

Non-classical current noise and light emission of an ac-driven tunnel junction

“…where the Gaussian rate scales as Γ G ( ) ∼ Γ 0 = πα 2 |T | 2 g c z 2 0 /ω 0 while the non-Gaussian rate scales as Γ nG ∼ λΓ 0 with λ defined as λ = g c z 2 0 . In the absence of ac drive, the Gaussian and non-Gaussian rates reduce to the previous results obtained by Xu et al [40,42].…”

“…Furthermore, the interaction with a local plasmon-polariton mode has been shown to be important for the overbias emission [37]. Taking the non-Gaussian fluctuations into account [39], this overbias light emission could be successfully explained by two-electron processes interacting with the local plasmon-polariton mode [40,41,42]. More recently even multi-electron processes have been observed experimentally in full agreement with the theory [43].…”

“…It is experimentally found that light emission occurs not only at energy lower than the dc bias but also at the overbias energy Ω > eV [37]. This overbias emission is successfully explained by two-electron and even multi-electron processes [40,42,43] emitting a single photon. However, light emission with time-dependent drive has not been investigated so far.…”

“…The Figure 5. Schematic setup for light emission from a STM junction coupled to a single resonant mode (SRM) (see [40,42]). Here the STM junction is modeled as a tunnel junction while the SRM is depicted by a LRC resonant circuit.…”

“…The tunnel amplitude between the two level is T and is modified as T e iαϕ(t) in the presence of voltage fluctuations. Here α is the coupling constant between the energy levels and the voltage fluctuations and is assumed to be weak since in most experiments the photon detectors are far away from the tunnel junctions [40,42].…”