Ravi Naik

QubiC: An open source FPGA-based control and measurement system for superconducting quantum information processors

  1. Yilun Xu,
  2. Gang Huang,
  3. Jan Balewski,
  4. Ravi Naik,
  5. Alexis Morvan,
  6. Bradley Mitchell,
  7. Kasra Nowrouzi,
  8. David I. Santiago,
  9. and Irfan Siddiqi
As quantum information processors grow in quantum bit (qubit) count and functionality, the control and measurement system becomes a limiting factor to large scale extensibility. To
tackle this challenge and keep pace with rapidly evolving classical control requirements, full control stack access is essential to system level optimization. We design a modular FPGA (field-programmable gate array) based system called QubiC to control and measure a superconducting quantum processing unit. The system includes room temperature electronics hardware, FPGA gateware, and engineering software. A prototype hardware module is assembled from several commercial off-the-shelf evaluation boards and in-house developed circuit boards. Gateware and software are designed to implement basic qubit control and measurement protocols. System functionality and performance are demonstrated by performing qubit chip characterization, gate optimization, and randomized benchmarking sequences on a superconducting quantum processor operating at the Advanced Quantum Testbed at Lawrence Berkeley National Laboratory. The single-qubit and two-qubit process fidelities are measured to be 0.9980±0.0001 and 0.948±0.004 by randomized benchmarking. With fast circuit sequence loading capability, the QubiC performs randomized compiling experiments efficiently and improves the feasibility of executing more complex algorithms.
arxiv pdf

A Multi-Resonator Network for Superconducting Circuits

  1. David C. McKay,
  2. Ravi Naik,
  3. Philip Reinhold,
  4. Lev S. Bishop,
  5. and David I. Schuster
Superconducting circuits have emerged as a configurable and coherent system to investigate a wide variety of quantum behaviour. This architecture — circuit QED — has been
used to demonstrate phenomena from quantum optics, quantum limited amplification, and small-scale quantum computing. There is broad interest in expanding circuit QED to simulate lattice models (e.g., the Jaynes-Cummings-Hubbard model), generate long-distance entanglement, explore multimode quantum optics, and for topological quantum computing. Here we introduce a new multi-resonator (multi-pole) circuit QED architecture where qubits interact through a network of strongly coupled resonators. This circuit architecture is a novel system to study multimode quantum optics, quantum simulation, and for quantum computing. In this work, we show that the multi-pole architecture exponentially improves contrast for two-qubit gates without sacrificing speed, addressing a growing challenge as superconducting circuits become more complex. We demonstrate the essential characteristics of the multi-pole architecture by implementing a three-pole (three-resonator) filter using planar compact resonators which couples two transmon-type qubits. Using this setup we spectroscopically confirm the multimode circuit QED model, demonstrate suppressed interactions off-resonance, and load single photons into the filter. Furthermore, we introduce an adiabatic multi-pole (AMP) gate protocol to realize a controlled-Z gate between the qubits and create a Bell state with 94.7% fidelity.
arxiv pdf