Gregory D Cunningham

High-Efficiency, Low-Loss Floquet-mode Traveling Wave Parametric Amplifier Characterization and Measurement

  1. Jennifer Wang,
  2. Kaidong Peng,
  3. Gregory D Cunningham,
  4. Andres Lombo,
  5. Alec Yen,
  6. Daniela Zaidenberg,
  7. William D. Oliver,
  8. and Kevin P. O'Brien
Advancing error-corrected quantum computing and fundamental science necessitates quantum-limited amplifiers with near-ideal quantum efficiency and multiplexing capability. However,existing solutions achieve one at the expense of the other. In this work, we experimentally demonstrate the first Floquet-mode traveling-wave parametric amplifier (Floquet TWPA). Fabricated in a superconducting-qubit process, our Floquet TWPA achieves minimal dissipation, quantum-limited noise performance, and broadband operation. Our device exhibits >20-dB amplification over a 3-GHz instantaneous bandwidth, <0.5-dB average in-band insertion loss, and the highest-reported intrinsic quantum efficiency for a TWPA of 92.1±7.6%, relative to an ideal phase-preserving amplifier. When measuring a superconducting qubit, our Floquet TWPA enables a system measurement efficiency of 65.1±5.8%, the highest-reported in a superconducting qubit readout experiment utilizing phase-preserving amplifiers to the best of our knowledge. These general-purpose Floquet TWPAs are suitable for fast, high-fidelity multiplexed readout in large-scale quantum systems and future monolithic integration with quantum processors.[/expand]
arxiv pdf

Near-Ideal Quantum Efficiency with a Floquet Mode Traveling Wave Parametric Amplfier

  1. Kaidong Peng,
  2. Mahdi Naghiloo,
  3. Jennifer Wang,
  4. Gregory D Cunningham,
  5. Yufeng Ye,
  6. and Kevin P. O'Brien
Broadband quantum-limited amplifiers would advance applications in quantum information processing, metrology, and astronomy. However, conventional traveling-wave parametric amplifiers
(TWPAs) support broadband amplification at the cost of increased added noise. In this work, we develop and apply a multi-mode, quantum input-output theory to quantitatively identify the sidebands as a primary noise mechanism in all conventional TWPAs. We then propose an adiabatic Floquet mode scheme that effectively eliminates the sideband-induced noise and subsequently overcomes the trade-off between quantum efficiency (QE) and bandwidth. We then show that a Floquet mode Josephson traveling-wave parametric amplifier implementation can simultaneously achieve >20dB gain and a QE of η/ηideal>99.9% of the quantum limit over more than an octave of bandwidth. Crucially, Floquet mode TWPAs also strongly suppress the nonlinear forward-backward wave coupling and are therefore genuinely directional. Floquet mode TWPAs can thus be directly integrated on-chip without isolators, making near-perfect measurement efficiency possible. The proposed Floquet scheme is also widely applicable to other platforms such as kinetic inductance traveling-wave amplifiers and optical parametric amplifiers.
arxiv pdf