Physics · the experiment
Keep the cat in its valley
A quantum bit that stores 0 and 1 in two valleys, a readout circuit that works as a drain, photons that multiply its protection. Four questions, from beginner to expert, on what keeps this cat in place.
1 · Find what cools the cat
Beginner
What removes the stray excitations that used to flip the qubit?
2 · Add four photons
Each added photon multiplies the bit-flip time by about 1.82. At one operating point, that time is 1 second.
Intermediate
What does it become with 4 more photons?
3 · Extend the photon lifetime
Phase flips follow the limit T₁ / (2 × number of photons), where T₁ is the lifetime of a photon in the circuit: about 8 microseconds here. Others have already demonstrated T₁ = 55.7 microseconds.
Expert
At the same number of photons, what would such a circuit change for the phase-flip time?
4 · Cool the readout circuit
The exchange between the cat and the readout resonator works both ways: thermal photons in the resonator can repopulate the excited states. They set a floor on the cooling.
Expert
What can be expected from a colder readout circuit?
Cat stabilised
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