Visualizing normalmodes¶

Qcircuit.
show_normal_mode
(mode, quantity='current', plot=True, return_fig_ax=False, add_title=True, add_legend=True, **kwargs)[source]¶ Plots a visual representation of a normal mode.
Only works if the circuit was created using the GUI. Plots a schematic of the circuit overlayed with arrows representing the complex amplitude of a certain quantity \(X\) which can be flux, current, charge or voltage.
More specifically, the complex amplitude of \(X\) if a singlephoton amplitude coherent state were populating a given mode
mode
.Current is shown in units of Ampere, voltage in Volts, charge in electron charge, and flux in units of the reduced flux quantum (defined as \(\hbar/2e\))
The direction of the arrows show what we are defining as positive current for that component.
 Parameters
mode (integer) – Determine what mode to plot, where 0 designates the lowest frequency mode, and the others are arranged in order of increasing frequency
quantity (string) – One of ‘current’ (default), ‘flux’,’charge’,’voltage’ Determines what quantity the arrows should represent.
plot (Boolean, optional) – If set to True (default), the function will call plt.show() to display the circuit
return_fig_ax (Boolean, optional) – If set to True (default is False), the function will return figure and axis for further processing using matplotlib.
add_title (Boolean, optional) – If set to True (default), the function will add a title detailing the modes frequency, anharmonicity and dissipation rate
add_legend (Boolean, optional) – If set to True (default), the function will add a legend detailing the definition of arrow size and arrow direction
Notes
This annotated quantity, called a phasor, is calculated by multiplying the voltage transfer function \(T_{rc}\) (between a reference component \(r\) and the annotated component \(c\) ), with \(X_{zpf,m,r}\), the zeropoint fluctuations of \(\hat{X}\) at the reference component.
Note that resistors make the transfer function \(T_{rc}\), and hence the phasors complex.
Since this is plotted for a singlephoton amplitude coherent state, the absolute value of the annotation is equal to the contribution of a mode to the zeropoint fluctuations accross this component.
For more detail on the underlying theory, see https://arxiv.org/pdf/1908.10342.pdf.