Autonomous cooling of Kerr-cat qubits to minutes-long bit-flip times

Abstract

Quantum error correction becomes more hardware efficient when physical noise is strongly biased towards one error channel. Cat qubits realize such a bias by encoding information in two opposite coherent states of a superconducting oscillator, so that bit flips are exponentially suppressed with photon number while phase-flip rates increase only linearly. In Kerr-cat qubits, a driven double-well potential confines these states and enables fast coherent control, but excitations can induce interwell switching, limiting bit-flip times to milliseconds. Here we show that the nonlinear interaction generating the confinement can also cool these excitations. When an intra-well transition becomes resonant with a lossy readout mode, excitations are transferred out of the qubit and dissipated, as established by spectroscopy and relaxation measurements. We observe the predicted exponential scaling of Kerr-cat bit-flip times with photon number, reaching 450 s, over five orders of magnitude beyond previous demonstrations. Phase-flip rates remain consistent with intrinsic photon loss at operating points with seconds-long bit-flip times. We further demonstrate fast Z gates without measurable degradation of bit-flip protection and single-shot readout with a bit-flip probability below 10⁻⁶ per measurement. Autonomous cooling thus brings minutes-long bit-flip protection to Kerr-cat qubits while retaining fast coherent control, without additional cooling drives or circuit elements.

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Cite

BibTeX RIS

BibTeX

@misc{hazanov2026autonomous,
  title = {{Autonomous cooling of Kerr-cat qubits to minutes-long bit-flip times}},
  author = {Sergey Hazanov and Mikhail Svintsov and Uri Goldblatt and Barkay Guttel and Fabien Lafont and Serge Rosenblum},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.04868},
  eprint = {2611.04868},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.04868},
  note = {CC BY-NC-ND 4.0},
}

RIS

TY  - UNPB
TI  - Autonomous cooling of Kerr-cat qubits to minutes-long bit-flip times
AU  - Sergey Hazanov
AU  - Mikhail Svintsov
AU  - Uri Goldblatt
AU  - Barkay Guttel
AU  - Fabien Lafont
AU  - Serge Rosenblum
PY  - 2026
DA  - 2026/11/03
PB  - arXiv
DO  - 10.48550/arxiv.2611.04868
UR  - https://arxiv.org/abs/2611.04868
AB  - Quantum error correction becomes more hardware efficient when physical noise is strongly biased towards one error channel. Cat qubits realize such a bias by encoding information in two opposite coherent states of a superconducting oscillator, so that bit flips are exponentially suppressed with photon number while phase-flip rates increase only linearly. In Kerr-cat qubits, a driven double-well potential confines these states and enables fast coherent control, but excitations can induce interwell switching, limiting bit-flip times to milliseconds. Here we show that the nonlinear interaction generating the confinement can also cool these excitations. When an intra-well transition becomes resonant with a lossy readout mode, excitations are transferred out of the qubit and dissipated, as established by spectroscopy and relaxation measurements. We observe the predicted exponential scaling of Kerr-cat bit-flip times with photon number, reaching 450 s, over five orders of magnitude beyond previous demonstrations. Phase-flip rates remain consistent with intrinsic photon loss at operating points with seconds-long bit-flip times. We further demonstrate fast Z gates without measurable degradation of bit-flip protection and single-shot readout with a bit-flip probability below 10^−6 per measurement. Autonomous cooling thus brings minutes-long bit-flip protection to Kerr-cat qubits while retaining fast coherent control, without additional cooling drives or circuit elements.
ER  -

Abstract

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