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4 votes
Accepted

Would an ambient-pressure, room-temperature superconductor eliminate the need for a dil-fridge in transmon processors?

TL;DR: The reason why some qubits need to work at very low temperature is to avoid noise which would make quantum gates having poor fidelity. For this reason, a room-temperature superconductor would ...
4 votes

Could you use $|0\rangle$ as excited state and $|1\rangle$ as ground state in transmon?

It would not make any difference whatsoever, as they are simply labels. "Red" and "blue" are equally valid names to give to qubits, albeit clunky ones. A rose by any other name ...
Dr. T. Q. Bit's user avatar
4 votes
Accepted

In a transmon qubit, what corresponds to the ground and excited states?

The transmon is a slightly nonlinear $LC$ resonator, with a resonance frequency of a few GHz. The image below, from Bardin et al., IEEE Microwave Magazine, 2020 (of which I am an author), shows in the ...
Ofer Naaman's user avatar
2 votes
Accepted

Why is there a frequency difference when performing ramsey experiment with setting neighbor qubits to different state?

the difference in frequency is precisely because the interaction is always on. Let's start with a scenario where there is no ZZ interaction. In this case, the Hamiltonian during the free evolution ...
Lior's user avatar
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1 vote
Accepted

What is the charge noise in the context of superconducting qubits?

For a complete answer (and much more!), see Charge insensitive qubit design derived from the Cooper pair box What is charge noise ? The energy of the capacitor in the transmon is $4 E_C (n-n_g)^2$ ...
francois-marie's user avatar
1 vote
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Frequency range of superconducting qubit

The transmon frequency $f_t$ is linked both to the charging energy $E_C$ and the inductive energy $E_L$ according to the formula: $$ f_t = \sqrt{8E_JE_C}. $$ where $E_C = e^2 / 2C$ and $E_L = (\phi_0 /...
francois-marie's user avatar

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