Memory for light as a component of quantum communication systems

Optical communication protocols that employ quantum nature of light are very secure. Their practical development is however hindered by optical losses, which limit the communication range to a few dozens of kilometers. This problem can be remedied by means of quantum repeaters, which reduce the effect of losses without compromising security. Implementation of quantum repeaters requires quantum memory for light - a tool that permits high-fidelity storage of quantum optical states in atomic ensembles. We will discuss ways in which such memory can be implemented, as well as the current state of the art, progress, and challenges faced by the research in the field.