class qucat.R(node_minus, node_plus, *args)[source]

A class representing an resistor

  • node_minus (integer) – Index corresponding to one node of resistor
  • node_minus – Index corresponding to the other node of the resistor
  • args (<float> or <str> or <float>,<str>) – Other arguments should be a float corresponding to the resistance, a string corresponding to the name of that value (ex: “R”), or both. If only a label is provided, a value for should be passed as a keyword argument in subsequent function calls (ex: R = 1e-9) This is the best way to proceed if one wants to sweep the value of this resistor. Indeed, the most computationally expensive part of the analysis is performed upon initializing the circuit, subsequently changing the value of a component and re-calculating a quantity such as the dissipation rate can be performed much faster.
zpf(mode, quantity, **kwargs)

Returns contribution of a mode to the zero-point fluctuations of a quantity for this component.

The quantity can be current current (in units of Ampere), voltage (in Volts), charge (in electron charge), or flux (in units of the reduced flux quantum, \(\hbar/2e\)).

  • mode (integer) – Determine what mode to consider, where 0 designates the lowest frequency mode, and the others are arranged in order of increasing frequency
  • quantity (string) – One of ‘current’, ‘flux’, ‘charge’, ‘voltage’
  • kwargs – Values for un-specified circuit compoenents, ex: L=1e-9.

contribution of the mode to the zero-point fluctuations of the quantity

Return type:



This quantity is calculated from the magnitude of the transfer function between a reference component an this one. The reference component is an inductor or a junction with inductance \(L_r\) for which we have calculated

\(\phi_{zpf,m} = \sqrt{\frac{\hbar}{\omega_mImY'(\omega_m)}}\)

the zero-point fluctuations in flux of mode \(m\) with frequency \(\omega_m\) using the admittance of the circuit calculated at the nodes of the reference junction

\(\phi_{zpf,m}\) can be transformed to other quantities

\(v_{zpf,m} = \omega\phi_{zpf,m}\)

\(i_{zpf,m} = v_{zpf,m} / L_r\omega\)

\(q_{zpf,m} = i_{zpf,m}/\omega\)

Where \(Z(\omega)\) is this components impedance.