Manipulating photonic signals by a multipurpose quantum junction

Abstract

We address a prototype integrated quantum circuit model system: a multifunctional quantum junction comprising three-level atomic nodes that couple two waveguides. We consider nodes with the $\mathrm{\ensuremath{\Lambda}}$ scheme of the allowed optical transitions, one of which is driven by an external classical electromagnetic field. We demonstrate that the latter field can be used to control the mode of the device operation: studying the dynamics of optical pulses, we show that the proposed integrated junction can operate as a controlled router or a switch, a 1/4 splitter, a delay line, or a storage node. The system offers also a possibility of intrinsic parallelism of quantum operations and can provide useful guidelines for making possible future quantum circuitry building blocks more scalable and integrated.