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Automated Qubit Spectroscopy

Is there a qubit? If yes, what are its properties?

cW -> pi pulse tune up -> t1 and t2 (ramsey and echo) -> anharmonicity -> chi (Cross kerr)

do step by step with good fitting functions then after fitting plug it into the next one

we are building the '->' steps. Need to sanity check the fitting, need a routine that says if the std error is to far to stop. for example, if the height of the peak is similar to the height we fitted then repeat with lower amplitude.

Qubit-Cavity Model

1. Cavity driven at resonance always
2. Drive qubit at a varying frequency _sensetive up to ~MHz

Variables: sweepStart, sweepStop, numPoints, VNAFreq, GenPower, VNAPower, numAverage,

Cavity Power, $\sqrt{\kappa} \epsilon (a+a^\dagger)$ where $\epsilon$ is voltage at port -> goes through attenuation before reaches cavity.

Decay as $\sqrt{\kappa}a$

Remember: Qubit has GHz Frequency range (>> $k_bT$ much larger than room temperature photons). Use frequency units with care (angular frequency)

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Spectroscopy is hard to do perfectly. Variables: Power, time of measurement, exciting the qubit at a lower frequency?

Initial goals

1. Using qutip, set up a quasi-realistic qubit-cavity model. Output is phase and amplitude from $a$. Add random Gaussian noise to the readout
2. Plot case for $P_{\text{cavity}} << 1$ photon and varying the power in the cavity versus qubit drive frequency (stack traces using colors for $P_{\text{cavity}}$)
3. Inspect number splitting (see Schuster thesis) if driving with more photons.