Uploading and evaluating custom controls

The computational tools powering BLACK OPAL may be leveraged to calculate the noise-susceptibility of a custom control uploaded via the interface.

This feature provides two unique capabilities:

  1. Control protocols derived independently through various means (e.g. via cancellation of terms in a Magnus expansion) may be compared alongside entries from the Q-CTRL library within the same filter-function framework.
  2. Real measured waveforms may be uploaded and performance metrics calculated to determine the impact of bandwidth limits or quadrature distortions due to transmission lines and other passive elements in real hardware systems.


Waveforms for custom controls must be properly formatted as CSV files in either Cartesian or Cylindrical coordinates. Broadly, we ask you to provide control amplitudes (normalized to the Maximum Rabi Rate) and sample durations; data sets may contain up to 10,000 time-domain samples defining a control operation as would be returned from common measurement hardware. Details on the required formatting are presented here, along with template files for upload. Once properly formatted, files may be uploaded through a drag-and-drop interface.

Files are automatically processed with the user-defined name, and loaded into the control library. You can now interact with these custom controls just like any other, including via Bloch-sphere visualizations and interactive charts. Note that when you upload a custom control these data will remain fixed even when you adjust Rabi rates, rotation angles, etc. We’ll remind you of this with an indicator:


In the above example (data available here) we have considered the impact of bandwidth-limits on a so-called WAMF control protocol. By considering different RC time constants applied to different controls you can directly evaluate the impact on noise-suppression of these limitations. We immediately see in the following figure that the impact of constraining the control bandwidth will negatively impact the performance of a WAMF control (see here for details on interpreting the filter function if this is unfamiliar to you).