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Bogoliubov Quasiparticles in Superconducting Qubits

by Leonid I. Glazman, Gianluigi Catelani

This Submission thread is now published as

Submission summary

Authors (as registered SciPost users): Gianluigi Catelani
Submission information
Preprint Link:  (pdf)
Date accepted: 2021-06-14
Date submitted: 2021-06-04 10:22
Submitted by: Catelani, Gianluigi
Submitted to: SciPost Physics Lecture Notes
Ontological classification
Academic field: Physics
  • Condensed Matter Physics - Experiment
  • Condensed Matter Physics - Theory
  • Quantum Physics


Extending the qubit coherence times is a crucial task in building quantum information processing devices. In the three-dimensional cavity implementations of circuit QED, the coherence of superconducting qubits was improved dramatically due to cutting the losses associated with the photon emission. Next frontier in improving the coherence includes the mitigation of the adverse effects of superconducting quasiparticles. In these lectures, we review the basics of the quasiparticles dynamics, their interaction with the qubit degree of freedom, their contribution to the qubit relaxation rates, and approaches to control their effect.

Author comments upon resubmission

We thank the Referee for the useful suggestions. We have implemented all of them.

  1. Explicit expressions for the phase slip amplitude and the transmon anharmonicity are added to the text after Eq. (29); in addition, we refer the reader to Ref. 6 for a detailed description of the energy levels. We also added a symmetry argument to explain the insensitivity of the qubit spectrum to e-jumps at n_g=1/4 and 3/4.

  2. All noticed typos have been fixed.

  3. The expression after Eq.(45) was also a typo, which has been corrected.

  4. We kept the form of the unitary transformation unchanged: it is correct and corresponds to redefining U as U^\dagger in the version given by the Referee.

  5. We have clarified the technical point related to the derivation of Eqs. (39) and (40) and, in addition, provided a reference to an alternative derivation of Eq. (40).

  6. We have introduced the definition of S_qp in Eq. (67).

  7. After Eq. (86), we expanded the explanation of the way the photon electric field couples to the superconducting phase and provided the necessary references to the equations appearing earlier in the text.

We believe the current version is acceptable for publication.

List of changes

changes made in response to the Referee's comments are listed in our reply

Published as SciPost Phys. Lect. Notes 31 (2021)

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