Transmon Lab

transmon.si

Research-grade circuit-QED instrument for transmon superconducting qubits. Explore the Hilbert-space map, inspect cited claims, ask the research assistant — no fake device metrics.

Jake Alphin · HumbleIllustrative ≠ measured
Depth

Primary path: pick a constellation node → read the equation → check notebook tags → ask the assistant. No hunting.

Selected: Transmon Hamiltonian

Subject constellation

Hilbert map

Click a node to open equations, depth-tuned notes, and lab-notebook citations.

Selected: Transmon Hamiltonian

Transmon HamiltonianTransmon HamiltonianεCharge dispersionαAnharmonicity αEJ/ECEJ / EC ratioΓPPurcell effectROReadout resonatorsXTCrosstalkT1/T2Decoherence T1 / T2GGate setCALCalibration loopsSCSurface-code context

Transmon Hamiltonian

hamiltonian
H=4ECn^2EJcosφ^H = 4 E_C \hat{n}^2 - E_J \cos\hat{\varphi}

In the circuit-QED Cooper-pair box / transmon picture, charge number n̂ and phase φ̂ are conjugate. With EJ ≫ EC the spectrum approaches a weakly anharmonic oscillator. Exact diagonalization in the charge basis (or Mathieu functions) yields eigenenergies En(ng) with residual gate-charge dependence.

Linked: charge-dispersion · anharmonicity · ej-ec

Canonical form H=4ECn^2EJcosφ^H = 4E_C \hat{n}^2 - E_J \cos\hat{\varphi} — conjugate charge and phase operators on the Josephson circuit.

Research assistant

Claude · grad

Ask about charge dispersion, α vs EJ/EC tradeoffs, Purcell filters, CZ vs iSWAP, or surface-code context. Answers stay rigorous — no invented lab numbers.

Lab notebook

Cited claims only

Every claim is tagged literature / textbook / assumption. Ranges are illustrative unless a primary citation supplies a measured value. Transmon Lab has no product hardware — never treat UI copy as experimental data.

Literaturekoch2007

Charge dispersion is exponentially suppressed as √(8 EJ/EC) grows; anharmonicity α ≈ −EC to leading order in the transmon expansion.

Foundational transmon proposal / analysis. Use for functional forms, not as a claim about any live device.

Koch et al., Phys. Rev. A 76, 042319 (2007)

Textbook / reviewgirvin2014

Circuit QED lecture notes / reviews provide the standard quantized-circuit derivation path from Lagrangian to Hamiltonian.

Pedagogical backbone for undergrad→grad depth.

Girvin, “Circuit QED: Superconducting Qubits Coupled to Microwave Photons” (Les Houches / notes)