Single Photons at JQI

See our Book- Single-Photon Generation and Detection: Physics and Applications (Nov. 2013 Academic Press) and our review article on Single-Photon Sources and Detectors in Review of Scientific Instruments


Affordable arbitrary TTL sequence generator

We present Fast TTL Pulse Generator project that is designed for researchers who need generating arbitrary pulse sequences on a limited budget. This design provides a high number of output channels (22) and user-programmable pulse structures and also allows using an external clock source. The shortest available pulse is approximately 20ns.

The principal hardware element is an FPGA development board which requires no significant modifications, except wiring the board which only involves basic soldering. The board is programmed with HDL Verilog and is connected to a standard PC via USB-2 cable.
This whole system is easy to assemble and consists of an extremely low cost solution to generate a high number of programmable TTL outputs.

-Source code

Want an inexpensive but powerful way to count coincidences between more than two channels?


How much would you pay for a computer linked coincidence circuit? Well, don't answer yet!


This system allows you to record coincidences between more than two channels. Need eight channels or more? No problem. This system will record any combination of coincidences between the input channels, that is not just coincidences between a mere two channels but any number of channels. But wait there's more.


This system can send you all of the coincidence events or filter out just the one you really want. That is all wonderful, but there is even more. The same hardware can be used for other applications. It can time tag events from all the channels and even be used to process analog pulses. Certainly you would expect to pay over $10,000 for such a system, but this system can be built for much less than even $1000. It can be built for only a few hundred dollars. We  show you how here.


This is designed to be an easy to follow recipe. Let us know how it works for you.

Low Cost FPGA solutions by others

Because a growing number of groups are publishing low cost FPGA solutions to multi-coincidence data taking problems, we are developing this page as a clearinghouse for such information.


Here is a list of links to other group's FPGA counting solutions


Coincidence Counter by Alan Stummer at U. of Toronto


Coincidence Counting Unit paper and  recipe by David Branning of Trinity College and Mark Beck of Whitman College


Multichannel Counter by Baronti et al.


Coincidence Counter by Majeed and Zukarnain


Multi-Channel Coincidence Counter by Pooser, et al