Abstract: Techniques are described for controlling qubits using baseband pulse sequences. Many, or even all, qubits in a system can be controlled by baseband pulse sequences that are synchronized to a clock signal shared by the qubits. The baseband pulse control techniques allow many qubits to be driven with the same parameterized baseband pulse sequence applied based on a common clock signal, with parameters of the baseband pulse sequence selected based on the desired operation. This approach greatly simplifies the electronics needed to drive a collection of qubits, as there is no need for picosecond timing, nor the complexities that arise from varied gate durations.

Abstract: Techniques are described for operating a qubit controller to generate a signal to apply to a qubit using a tunable coupler that controls the amplitude of at least part of the signal. The qubit controller may comprise a plurality of digital-to-analog converters that each convert digital values to an analog waveform. The qubit controller may further comprise a plurality of tunable couplers each coupled to a respective DAC that adjusts the amplitude of the analog waveform from the respective DAC. The tunable couplers thereby produce a plurality of analog waveforms, which may be combined to produce a signal to apply to the qubit. In some embodiments, the tunable couplers may each be configured to receive a respective control signal that dictates the scaling factor which that tunable coupler applies to the analog waveform.