Drag effects in the system of electrons and microcavity polaritons

TL;DR

This paper develops a theory of drag effects between electrons and polaritons in coupled quantum wells within microcavities, revealing how electron currents induce polariton flows and how superfluidity suppresses electron drag at low temperatures.

Contribution

It introduces a theoretical framework for understanding drag effects in electron-polariton systems, highlighting superfluidity signatures and providing calculations of drag coefficients.

Findings

Electron current induces polariton flow at low temperatures.

Superfluidity suppresses electron drag below transition temperature.

Drag coefficients are calculated and analyzed for different regimes.

Abstract

The theory of the drag effects in the system of spatially separated electrons and excitons in coupled quantum wells (QW) embedded in an optical microcavity is developed. It is shown that at low temperature an electron current induces the (normal component) polariton flow, therefore, a transport of photons along the cavity. However, the electron current dragged by the polariton flow is strongly suppressed below polariton superfluid transition temperature and hence, the strong suppression of the induced electron current indicates the superfluidity of polaritons. Therefore, the transport properties of polaritons can be investigated by measuring the current or voltage in the electron subsystem. At high temperatures we study the exciton-electron drag effects. At high temperatures regime, from one hand, the existence of the electric current in an electron QW induces the exciton flow in the other QW, from the other hand, the electron current in one QW induces the exciton flow in the other QW via the drag of excitons by the electrons. The drag coefficients for the polariton-electron systems are calculated and analyzed. We discuss the possible experimental observation of the drag effects in the system of electrons and microcavity polaritons, that also allow to observe the cavity polaritons superfluidity.