PREDICT

Predict the frequency with an ohmmeter

Ambegaokar–Baratoff I_c = πΔ / (2eR_n).

Room temperature Every junction on a wafer can be probed.

Calibration Resistance rises slightly on cooling.

A resistance measurement predicts a quantum frequency.

COLLISIONS

When neighbours collide

Too close Neighbours within about 20 MHz.

1→2 match One qubit's f₀₁ lands on a neighbour's f₁₂.

Yield Large chips almost always have collisions.

Precision gets harder as chips grow.

TRIMMING

Measure Every junction's resistance.

Anneal Laser heat raises resistance and lowers frequency.

Repeat Until each qubit is on target.

Fabrication can be corrected after the fact.

GAME

Goal All six qubits within ±8 MHz.

One way only Annealing only lowers the frequency.

Strategy Stop as soon as a qubit is in its window.

Real trimming tools automate exactly this loop.

TWO PHILOSOPHIES

Fixed Simpler and quieter, but must be trimmed.

Tunable Flexible, but sensitive to flux noise.

Both Each is used in leading processors.

Each choice moves the difficulty somewhere else.

UNIT 25 STUDY COMPLETE

🎯

You've predicted a qubit's frequency with an ohmmeter, counted collisions, trimmed a whole chip and compared fixed and tunable designs.