Bistable Spin Currents from Quantum Dots Embedded in a Microcavity

TL;DR

This paper investigates how quantum dots in a microcavity can generate bistable spin currents through spin flip transitions driven by a quantized electromagnetic field, revealing bimodal behavior even with a single dot.

Contribution

It introduces a model linking quantum dot spin transport with cavity quantum electrodynamics, demonstrating bistability and bimodal distributions in spin current and cavity field.

Findings

Cavity field amplitude and spin current show bistability with laser driving.

Single-dot systems exhibit bimodal cavity field and spin current distributions.

The model parallels the Jaynes-Cummings model in quantum optics.

Abstract

We examine the spin current generated by quantum dots embedded in an optical microcavity. The dots are connected to leads, which allow electrons to tunnel into and out of the dot. The spin current is generated by spin flip transitions induced by a quantized electromagnetic field inside the cavity with one of the Zeeman states lying below the Fermi level of the leads and the other above. In the limit of strong Coulomb blockade, this model is analogous to the Jaynes-Cummings model in quantum optics. We find that the cavity field amplitude and the spin current exhibit bistability as a function of the laser amplitude, which is driving the cavity mode. Even in the limit of a single dot, the spin current and the Q distribution of the cavity field have a bimodal structure.