What’s the difference between the DriveChannel and the Control Channel?

Question

In my incredibly elementary understanding of superconducting qubits, a qubit is an LC circuit where the inductor has been replaced with a Josephson junction. In this system, microwave pulse operations to implement transformations on the qubit is achieved by a microwave drive line which coupled to the qubit with a capacitor.

In Qiskit Pulse, we usually play our pulses on the DriveChannel, which I assume is directly related to the time varying voltage at the end of the microwave drive line (though I’m a little unsure of where the AWGs come in?). In this big picture, I’m not so sure where the ControlChannel comes into play. All the Qiskit docs say is that it is “associated with multi-qubit gates,” but I am still unsure of how the ControlChannel is physically implemented or when to use it instead of the regular DriveChannel.

Answer 1

Each instruction type has its own set of operands. As you can see above, they each include at least one Channel to specify where the instruction will be applied.

Channels are labels for signal lines from the control hardware to the quantum chip.

• DriveChannels are typically used for driving single qubit rotations,
• ControlChannels are typically used for multi-qubit gates or additional drive lines for tunable qubits,
• MeasureChannels are specific to transmitting pulses which stimulate readout, and
• AcquireChannels are used to trigger digitizers which collect readout signals.

DriveChannels, ControlChannels, and MeasureChannels are all PulseChannels; this means that they support transmitting pulses, whereas the AcquireChannel is a receive channel only and cannot play waveforms.

explanation from(check out those example) : https://github.com/Qiskit/qiskit-tutorials/blob/master/tutorials/circuits_advanced/06_building_pulse_schedules.ipynb
also https://qiskit.org/documentation/experiments/apidocs/calibration_management.html