DC-powered broadband quantum-limited microwave amplifier

  1. N. Nehra,
  2. N. Bourlet,
  3. A. H. Esmaeili,
  4. B. Monge,
  5. F. Cyrenne-Bergeron,
  6. A. Paquette,
  7. M. Arabmohammadi,
  8. A. Rogalle,
  9. Y. Lapointe,
  10. and M. Hofheinz
Fast, high-fidelity, single-shot readout of superconducting qubits in quantum processors demands quantum-limited amplifiers to preserve the optimal signal-to-noise ratio. Typically, quantum-limited amplification is achieved with parametric down-conversion of a strong pump tone, which imposes significant hardware overhead and severely limits scalability. Here, we demonstrate the first DC-powered broadband amplifier operating within 0.2 photons of the quantum limit. Our impedance-engineered Inelastic Cooper-pair Tunneling Amplifier (ICTA)-a voltage-biased SQUID in which Cooper pairs tunnel inelastically by emitting signal-idler photon pairs-operates in reflection, delivering 13 dB of average gain across a 3.5 GHz bandwidth in a single stage. Semiclassical simulations accurately predict the gain and saturation power, enabling further design improvements. By eliminating the pump-tone infrastructure, the broadband ICTA promises to dramatically reduce the hardware complexity of quantum-limited amplification in superconducting quantum processors.
arxiv pdf

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