Spin current and shot noise from a quantum dot coupled to a quantized cavity field

TL;DR

This paper investigates spin current and shot noise in a quantum dot coupled to a cavity field, revealing quantum optical effects like photon-spin current equivalence and noise features due to photon discreteness.

Contribution

It introduces a model linking quantum dot spin transport to cavity quantum electrodynamics, highlighting quantum effects absent in classical field scenarios.

Findings

Photon current equals spin current.

Spin current can surpass classical driving cases.

Frequency-dependent shot noise shows characteristic dips and peaks.

Abstract

We examine the spin current and the associated shot noise generated in a quantum dot connected to normal leads with zero bias voltage across the dot. The spin current is generated by spin flip transitions induced by a quantized electromagnetic field inside a 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 also calculate the photon current and photon current shot noise resulting from photons leaking out of the cavity. We show that the photon current is equal to the spin current and that the spin current can be significantly larger than for the case of a classical driving field as a result of cavity losses. In addition to this, the frequency dependent spin (photon) current shot noise show dips (peaks) that are a result of the discrete nature of photons.