One of the most important elements in designing superconducting or spin qubit based quantum processors is the control electronics that provide the needed controls for operating the qubits. Qubits are controlled by precise microwave signals that will determine what gate operations are performed in accordance with the desired software program. The overall accuracy and noise levels of these signals can have a great effect on qubit quality measures such as gate fidelity and coherence times and engineers would like to make them as perfect as possible. Keysight has developed a new modular Quantum Control System that provides high levels of signal accuracy using a technology called Direct Digital Synthesis. What this means is that if a system needs to provide a signal at for example a 5 Ghz. frequency, the system will generate that frequency directly using very high speed ASICs and Digital to Analog Converters (DACs). Other control electronics implementations will generate the signals at a lower frequency and then upconvert the signals using mixers to the required 5 Ghz. The problem is that those mixers can generate phase noise, suffer from drift, and require calibrations, resulting in a control signal that is less precise that will negatively impact the qubit gate fidelities. A key specification for the new Keysight system is that of phase noise they have been able to reduce to a very low level of less than 130 dBm.
The system is configurable with multiple modules that can be inserted into an 18 slot chassis with functionality that can synchronize multiple modules or multiple chassis together to act as one unit. The system also includes a Quantum-specific Python API software package that provides for Static System Configurations, Device Calibration Manager, Waveform and Data Visualization Tools and other tools that the company asserts is easy to use.
June 21, 2022