Chiral Behavior Observed in Artificial Atoms
Researchers from the California Institute of Technology have developed a nonreciprocal device, an "artificial atom" made from a superconducting circuit, which can be coupled exclusively to either left- or right-moving signals in a microwave waveguide. This chiral design could be used in quantum networks to enable control over information flow between multiple artificial atoms coupled to a waveguide. The researchers achieved this by using additional superconducting artificial atoms as couplers between the emitter atom and the waveguide, and the relative phase between the modulations of the two couplers yielded the crucial phase difference that either let forward- or backward-propagating light pass through the waveguide.