OPD - Operator Digital¶
The OPD is a separate box that enhances the OPX input with 10 more digital signals. These 10 inputs have programmable thresholds and are sampled at 1ns resolution. They are \(50 \Omega\) matched and accept up to 3.3V (LVTTL).
The OPD is directly connected to the OPX. When it is present, the input channels can be defined in the configuration file similarly to other channels. For example:
When defining a digital input, several parameters needs to be defined:
polarity- Whether it is triggered when
RISING(rising edge) or
deadtime- Minimal time between pulses in ns. e.g., If it is set to 16ns, then only the 1st pulse out of two pulses 10ns apart will be detected. 'deadtime' should be between 4 and 16ns.
threshold- Voltage threshold
Once defined in the controller, it can be used in a quantum element as follows:
Time Tagging with the OPD is done similarly to a normal time tagging measurement:
timesis a vector of integers that is populated by the measurement.
max_timegives the maximum time window, in ns, during which the statement waits for tag arrival.
countsis a variable that is populated with the number of tags which arrived during the measurement.
element_outputmust be defined if the
elementhas more than one digital output. In this case, it is a string indicating the output to be measured. It can be left empty when the element has only one input (default is empty string).
The time-tagging operation ends either at the set duration or when the
times is fully populated (first one of the two).
Note that the information in
times is only valid up to
In addition, with the OPD you can directly count pulses:
countsis a variable that is populated with the number of pulses which arrived during the measurement.
max_timegives the maximum time window, in ns, during which the statement waits for incoming pulses.
element_outputsmust be defined if the
elementhas more than one digital input. In this case, it is either a string indicating the output to be measured or a tuple with list of strings corresponding to the outputs to be measured. It can be left empty when the element has only one input (default is empty string).
Wait for trigger¶
It is possible for any element to wait until a pulse arrives at one of the OPD inputs. This is done with the
element_waitingis the element waiting.
pulse_to_playis the name of the pulse to play on the element while waiting for the external trigger. Must be a constant pulse. Can be None to play nothing while waiting.
trigger_elementis an element with digital inputs, when one of his digital inputs is triggered, the
element_waitingwill continue. If
trigger_elementhas multiple digital inputs, a specific one must be chosen:
trigger_elementcan be a tuple, with the 1st item being the element name and the 2nd item being the trigger input. If
trigger_elementis left empty, then it waits for the trigger input in the back panel of the OPX.
See also the following guide on external triggering