Energetics of microwaves probed by double quantum dot absorption

TL;DR

This paper investigates how microwaves interact with a double quantum dot system, revealing wave-particle duality and energy scales that depend on drive strength, with implications for quantum electronics and photon detection.

Contribution

It demonstrates the transition from photon-energy to wave-amplitude dominated regimes in double quantum dot absorption, introducing a microwave photoelectric effect analogy.

Findings

Single photon energy governs absorption in weak drive

Wave amplitude dominates in strong drive, creating bias triangles

Threshold between regimes set by the fine-structure constant

Abstract

We explore the energetics of microwaves interacting with a double quantum dot photodiode and show wave-particle aspects in photon-assisted tunneling. The experiments show that the single photon energy sets the relevant absorption energy in a weak-drive limit, which contrasts the strong drive limit where the wave amplitude determines the relevant-energy scale and opens up microwave induced bias triangles. The threshold condition between these two regimes is set by the fine-structure constant of the system. The energetics are determined here with the detuning conditions of the double dot system and stopping-potential measurements that constitute a microwave version of the photoelectric effect.