Improved interface for a quantum internet

A quantum network requires efficient interfaces over which information can be transferred from matter to light and back. In the current issue of Physical Review Letters, Innsbruck physicists led by Rainer Blatt and Tracy Northup show how this information transfer can be optimized by taking advantage of a collective quantum phenomenon. Two particles are positioned between highly reflective mirrors and entangled with one another by means of a laser. Additional lasers encode quantum information in the ions and then transfer the information to a single photon. (Graphic: U. Innsbruck) Quantum computers are no longer just a theoretical concept. In recent years, researchers have assembled and successfully tested the building blocks for a future quantum computer in the laboratory. More than a dozen candidate technologies are currently being studied; of these, ion traps are arguably the most advanced.