Coincidence Logic Unit
The UQD-Logic is a logic correlation unit, conceived by UQD co-founder Thomas Jennewein, is designed and built in cooperation with Thomas Lehner of DotFast. This unit effectively combines a timing analyzer, coincidence logic unit and counters for 16 input channels into one device. It is truly unique, as it manages continuous operation speeds for coincidence counting of 100 MHz combined over all input signals, with timing resolution of 156.25 ps (16 channel firmware) or 78.125 ps (8 channel firmware). Each individual channel can be measured at a burst rate of 200 MHz, with a buffer of 1024 events.
All events are counted onboard the unit, and any of the possible correlation patterns for the 16 input channels can be counted. The unit also supports time-tagging transfer at a continuous rate of about 11 MSamples/s to the host PC.
The data interface is USB 2.0, and software drivers for Microsoft Windows and Linux are available. Sample code for LabView, VisualBasic, cpp are provided.
This unit is so flexible, it will most likely cover many needs for experiments that studies correlated detections of single-photon detectors.
Some specific examples of experiments where these instruments can be utilized:
- high count rate entanglement sources
- multi-photon experiments such as optical quantum computing
- quantum communications and cryptography research based on single and entangled photons
- feed-forward quantum optics experiments including gated detectors and triggered optical modulators
- time correlated flourescence
The UQD logic offers several unique features, which make it very versatile for multi-photon counting experiments:
Three-state coincidence patterns search: an arbitrary number of patterns can be counted, whereby each input can be configured in three possible states: “coincidence”, “ignore” and “anti-coincidence”.
Time-tagging filter: With UQD’s unique pattern filtering a low-level data reduction is implemented within the unit. It will only transmit time-tag data to the host PC if a minimal number of coincidences was observed in certain timing window. This feature enables the researcher to record time-tag signal time tags over extended periods of time, man hours, without ending up with many GigaByte large files which are difficult to handle and analyze.
Adjustable input discriminator:
Each input is terminated with 50 Ohm, and the discriminator threshold can be adjusted from +2V to -2V, and trigger a positive or negative edge.