Add timing visualization page

[beckykd]

closes #3848
closes #4045

preview: https://qiskit.github.io/documentation/pr-3950/docs/guides/visualize-circuit-timing

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[jyu00]

We should also explain the X and Y axises in the generated figure. @RoyElkabetz is the following correct?

• X axis is time in unit dt
• Y axis is the channel
  • Receive channel is ???
  • Qubit x is the drive channel for qubit x
  • AWGRx_y (Arbitrary Wave Generator Readout) is used for readout channels communication for measuring qubits. The x and y arguments correspond to the readout instrument ID and the qubit number, respectively.
  • Hub controls broadcasting

Similarly, we should explain how to read the instructions on the figure - each instruction has the format of X_Y, where X is the name of the instruction and Y is the pulse type. A play type applies control pulses, and a capture records the qubit's state.

This would have been so much easier if we still have pulse library and can just point to that 😛

[RoyElkabetz]

- X axis is time in unit dt
- Y axis is the channel
    - Receive channel is ???
    - Qubit x is the drive channel for qubit x
    - AWGRx_y (Arbitrary Wave Generator Readout) is used for readout channels communication for measuring qubits. The x and y arguments correspond to the readout instrument ID and the qubit number, respectively.
    - Hub controls broadcasting

• So the X-axis is in units of hardware cycles, where each cycle should take a single dt of seconds, it may vary depending on the specific hardware you are using.
• The Y-axis is for Channels. You can think of Channels as instruments that emit pulses.
• The Receive channel is the only channel which is not an instrument by itself, it is an instruction which is played on all channels that are part of a communication procedure with the Hub in that moment in time.
• All the rest of the statements are correct.

[mbhealy]

• So the X-axis is in units of hardware cycles, where each cycle should take a single dt of seconds, it may vary depending on the specific hardware you are using.

This is what dt means, 1 dt == 1 scheduling cycle. dt is a defined increment of time and has unit seconds.