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 a 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 nonideal Z errors.

[1]  S. Girvin,et al.  Observation of high coherence in Josephson junction qubits measured in a three-dimensional circuit QED architecture. , 2011, Physical review letters.

[2]  John M. Martinis,et al.  Logic gates at the surface code threshold: Superconducting qubits poised for fault-tolerant quantum computing , 2014 .

[3]  Blake R. Johnson,et al.  Simple all-microwave entangling gate for fixed-frequency superconducting qubits. , 2011, Physical review letters.

[4]  Erik Lucero,et al.  Surface loss simulations of superconducting coplanar waveguide resonators , 2011, 1107.4698.

[5]  Erik Lucero,et al.  Minimizing quasiparticle generation from stray infrared light in superconducting quantum circuits , 2011 .

[6]  Jay M. Gambetta,et al.  Tomography via Correlation of Noisy Measurement Records , 2013, 1310.6448.

[7]  J. Gambetta,et al.  Procedure for systematically tuning up cross-talk in the cross-resonance gate , 2016, 1603.04821.

[8]  Joseph Emerson,et al.  Scalable and robust randomized benchmarking of quantum processes. , 2010, Physical review letters.

[9]  Andrew G. Glen,et al.  APPL , 2001 .

[10]  S. Poletto,et al.  Detecting bit-flip errors in a logical qubit using stabilizer measurements , 2014, Nature Communications.

[11]  Andrew W. Cross,et al.  Implementing a strand of a scalable fault-tolerant quantum computing fabric , 2013, Nature Communications.

[12]  J. Gambetta,et al.  Bulk and surface loss in superconducting transmon qubits , 2015, 1509.03859.

[13]  Jay M. Gambetta,et al.  Process verification of two-qubit quantum gates by randomized benchmarking , 2012, 1210.7011.

[14]  Jay M. Gambetta,et al.  Improved superconducting qubit coherence using titanium nitride , 2013, 1303.4071.

[15]  Andrew W. Cross,et al.  Demonstration of a quantum error detection code using a square lattice of four superconducting qubits , 2015, Nature Communications.

[16]  Luigi Frunzio,et al.  Surface participation and dielectric loss in superconducting qubits , 2015, 1509.01854.

[17]  Joseph V. Minervini,et al.  Superconductor Science and Technology (SUST), Guest Editor , 2016 .

[18]  R. Barends,et al.  Superconducting quantum circuits at the surface code threshold for fault tolerance , 2014, Nature.

[19]  G. S. Paraoanu,et al.  Microwave-induced coupling of superconducting qubits , 2006, 0801.4541.

[20]  A. Kitaev,et al.  Quantum codes on a lattice with boundary , 1998, quant-ph/9811052.

[21]  John M. Martinis,et al.  State preservation by repetitive error detection in a superconducting quantum circuit , 2015, Nature.

[22]  M Steffen,et al.  Characterization of addressability by simultaneous randomized benchmarking. , 2012, Physical review letters.

[23]  Chad Rigetti,et al.  Josephson amplifier for qubit readout , 2011, 1103.1405.

[24]  Chad Rigetti,et al.  Fully microwave-tunable universal gates in superconducting qubits with linear couplings and fixed transition frequencies , 2010 .

[25]  A. Kitaev.  Fault tolerant quantum computation by anyons , 1997, quant-ph/9707021.

[26]  M. Weides,et al.  Improving the Coherence Time of Superconducting Coplanar Resonators , 2009, 0909.0547.

[27]  R. J. Schoelkopf,et al.  Analog information processing at the quantum limit with a Josephson ring modulator , 2008, 0805.3452.

[28]  Robert Raussendorf,et al.  Fault-tolerant quantum computation with high threshold in two dimensions. , 2007, Physical review letters.

[29]  Antonio Corcoles,et al.  Protecting superconducting qubits from radiation , 2011 .

[30]  Shor,et al.  Scheme for reducing decoherence in quantum computer memory. , 1995, Physical review. A, Atomic, molecular, and optical physics.

[31]  J. Gambetta,et al.  Superconducting qubit in a waveguide cavity with a coherence time approaching 0.1 ms , 2012, 1202.5533.