= Superconducting quantum computer need non-linear components
Non-linearity is needed otherwise the input energy would just make the state go to higher and higher energy levels, e.g. from 1 to 2. But we only want to use levels 0 and 1.
The way this is modelled in by starting from a pure <LC circuit>, which is an harmonic oscillator, see also <quantum LC circuit>, and then replacing the linear <inductor> with a <SQUID device>, e.g. mentioned at: https://youtu.be/eZJjQGu85Ps?t=1655 <video Superconducting Qubits I Part 1 by Zlatko Minev (2020)>.