Your First Superconducting Qubit: Intro to cQED, Part II

Part of the series Superconducting Qubits 101; cited as one entry below.

Second half of a beginner cQED lecture titled "Your First Superconducting Qubit". It goes from Dirac's canonical quantization and ladder operators to the transmon treated as a weakly nonlinear (Kerr) oscillator, then shows how real devices are modeled: classical EM simulation, quantization (with energy-participation ratios as the worked example), and the effective Hamiltonian with dispersive shifts. Backup slides hold hand-written notes on energy, flux fluctuations and the compactness of the junction phase.

• Canonical quantization: Poisson brackets to commutators, ladder operators, Husimi Q phase-space pictures
• Transmon as a Kerr oscillator: to first order (in the RWA) the nonlinearity shifts energies, giving anharmonicity and a Lamb shift, while the Fock eigenstates are unchanged
• Three-step device modeling: EM eigenmodes, quantization via EPR, and the effective qubit-cavity Hamiltonian with cross-Kerr chi
• Backup notes on flux fluctuations, harmonic approximation and a tight-binding picture of the junction phase

Summary and key points drafted by a language model from the slides, not yet reviewed by me. The slides are the source.

Cite

@misc{minev2026superconductingqubits101,
  author = {Zlatko K. Minev},
  title = {{Superconducting Qubits 101}},
  howpublished = {Lecture series},
  year = {2026},
  url = {https://zlatko-minev.github.io/zlatko-minev-quantum-repository/series/superconducting-qubits-101/},
  note = {Slides, 7 decks, 2020--2026; given at CEC ICMC; Flagship Quantum Device Workshop (Beginner); QIQT Summer School; Qiskit Global Summer School; Quantum Device Workshop (Beginner)}
}

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