The AWG (Arbitrary Waveform Generator) in this calibration flow is a class of widely available signal sources. In the “manipulate” stage, an AWG is used to excite the qubit and move it to a particular state. The AWG can send a pulse shape to the processor in the experimental system and use the waveform to adjust the qubit, secure correct measurements for that processor, and eventually excite that qubit into some state. The manipulate stage also includes measurement self-calibration by using the AWG to observe. In the “read” phase, the AWG pulse can trigger an oscilloscope measurement or a readout into some other measurement system, such as an FPGA-based system. The AWG can also perform the waveform adjustments necessary for a correct measurement. So, in some cases, researchers work with the AWG to correct that waveform by making small adjustments to capture the measurement desired. The waveform being modified is the same file the AWG uses for generation. Researchers can correct waveform files using tools like those in MATLAB® or proprietary tools like Tektronix's SourceXpress® software. In this setup, the oscilloscope is primarily reading the commands, confirming through visualization that those commands are being sent and received by the controller.
The heart of the experimental process takes place in the “adjust” stage. The AWG's pulse shape can be modified to support the processor requirements by modifying the frequency or the up-conversion, or by adjusting the sample rate to determine what's needed to excite a qubit to move it into a different state. Researchers can continue to adjust and correct that waveform and sequencing of all the different waveforms coming out of the AWG. Next, it's time for the researcher to reconduct the experiment. Timing is critical in quantum experiments, so researchers need signal sources that can recompile and resend a waveform fast when modifying feedback loops.
