Pulse Counter Option

The HDAWG-CNT Pulse Counter enables the analysis of up to 8 pulse trains in parallel, enabling event-based measurements (e.g., photon detection using photo-multiplier tubes) at a maximum count rate of 300 MHz. There are 4 distinct modes of operation, and each channel offers an adjustable discriminator with a range of ±10 V. Measurement results from the pulse counters can be conveniently analyzed with the LabOne toolset, which features time-domain and histogram displays. Based on the counter values, branching conditions for the HDAWG Arbitrary Waveform Generator can be defined to implement ultra-fast feed-forward loops for quantum error correction.

HDAWG-CNT upgrade and compatibility

• Field-upgradeable option
• Compatible with all other HDAWG options

The HDAWG-CNT Pulse Counter option enables the measurement of randomly distributed pulses. Each trigger input of the HDAWG is linked to an individual counter unit and operates in one of the following modes:

• Free-running: the counter runs in repeated periods defined by a configurable timer. At the beginning of each period the counter is reset, and at the end the accumulated number of counts is output.
• Gated: the counter is controlled by a gate input signal applied to one of the trigger inputs. The counter is enabled at the rising edge of the gate signal. At the falling edge, the counter is disabled and the accumulated number of counts is returned.
• Gated free-running: this mode is similar to the free-running mode, but features additional control by a gate input signal on one of the trigger inputs. The counter operates only when the gate signal is high. Both the counter and the timer are reset when the gate signal is low.
• Time tagging: every event is individually recorded and transmitted to the host computer along with a time tag.

All modes feature background subtraction, i.e., take into account measurement values from two separate counters and count integration over time.

In combination with the HDAWG Arbitrary Waveform Generator, the HDAWG-CNT introduces advanced cross-triggering functionality for complex pulsed experiments in quantum optics. Each of the counters can be initialized and reset within AWG sequences. Conversely, counter values can serve as trigger and branching conditions in sequence definitions.