Demonstration of weight-four parity measurements in the surface code   architecture
  We present parity measurements on a five-qubit lattice with connectivity amenable to the surface code quantum error correction architecture. Using all-microwave controls of superconducting qubits coupled via resonators, we encode the parities of four data qubit states in either the $X$- or the $Z$-basis. Given the connectivity of the lattice, we perform full characterization of the static $Z$-interactions within the set of five qubits, as well as dynamical $Z$-interactions brought along by single- and two-qubit microwave drives. The parity measurements are significantly improved by modifying the microwave two-qubit gates to dynamically remove non-ideal $Z$ errors. 
Maika Takita, A. D. C\'orcoles, Easwar Magesan, Baleegh Abdo, Markus   Brink, Andrew Cross, Jerry M. Chow, Jay M. Gambetta
quant-ph