Coherent exciton-polariton devices

The Bose–Einstein condensate of exciton-polaritons has emerged as a unique, coherent system for the study of non-equilibrium, macroscopically coherent Bose gases, while the full confinement of this coherent state to a semiconductor chip has also generated considerable interest in developing novel applications employing the polariton condensate, possibly even at room temperature. Such devices include low-threshold lasers, precision inertial sensors, and circuits based on superfluidity with ultra-fast non-linear elements. While the demonstration and development of such devices are at an early stage, rapid progress is being made. In this review, an overview of the exciton-polariton condensate system and the established and emerging material systems and fabrication techniques are presented, followed by a critical, in-depth assessment of the ability of the coherent polariton system to deliver on its promise of devices offering either new functionality and/or room-temperature operation. (topical review)