Time-dependent current into and through multilevel parallel quantum dots in a photon cavity

TL;DR

This paper provides a theoretical analysis of time-dependent charge transport in a nanoscale system with parallel quantum dots in a photon cavity, revealing how gate voltage and photon states influence resonant and inelastic tunneling phenomena.

Contribution

It introduces a detailed model of photon-assisted transport in multilevel quantum dot systems, highlighting the impact of initial photon number and internal relaxation channels on steady-state currents.

Findings

Resonant transport occurs when the two spin components of the one-electron ground state are in the bias window.

Transport current is largely independent of detuned photon fields in the small bias regime.

Initial photon number influences the time to reach the steady state and affects inelastic tunneling processes.

Abstract

We analyze theoretically the charging current into, and the transport current through, a nanoscale two-dimensional electron system with two parallel quantum dots embedded in a short wire placed in a photon cavity. A plunger gate is used to place specific many-body states of the interacting system in the bias window defined by the external leads. We show how the transport phenomena active in the many-level complex central system strongly depend on the gate voltage. We identify a resonant transport through the central system as the two spin components of the one-electron ground state are in the bias window. This resonant transport through the lowest energy electron states seems to a large extent independent of the detuned photon field when judged from the transport current. This could be expected in the small bias regime, but an observation of the occupancy of the states of the system reveals that this picture is not entirely true. The current does not reflect slower photon-active internal transitions bringing the system into the steady state. The number of initially present photons determines when the system reaches the real steady state. With two-electron states in the bias window we observe a more complex situation with intermediate radiative and nonradiative relaxation channels leading to a steady state with a weak nonresonant current caused by inelastic tunneling through the two-electron ground state of the system. The presence of the radiative channels makes this phenomena dependent on the number of photons initially in the cavity.