How to make private git repositories open for public access

Some of my personal projects are tracked using private git repositories, hosted on this server. I can access these via ssh, but for a while I've had in mind to make at least a couple of them publicly accessible... somehow. After finally getting around to looking into it, this turns out to be deceptively simple using git-daemon (instructions for Debian distros):

  1. Install the git-daemon-sysvinit package.
  2. Enable the daemon by editing /etc/default/git-daemon. Reboot, or start the git-daemon service by hand.
  3. Add a symlink to each git repo you want to make public under /var/lib/git. These will then be accessible via git://<hostname>/git/<linkname>.
  4. Ensure the git protocol port (9418) forwards to the server.

Simple! The git protocol is faster than serving over http(s), and the standard configuration ensures that anonymous clients can pull, but not push, which is exactly what I was after.

Over the …

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Published in EPJ Quantum Technology: Laser annealing heals radiation damage in avalanche photodiodes

Following our detector radiation and mitigation testing campaign, we tried an alternative approach for annealing detectors to mitigate radiation damage: laser annealing. High-power laser light was directed at irradiated and thermally-annealed detector samples, and subsequent performance measured. Notably, the results show that doing so provides performance improvements better than those achieved by thermal annealing.

J. G. Lim, E. Anisimova, B. L. Higgins, J.-P. Bourgoin, T. Jennewein, and V. Makarov
EPJ Quantum Technology 4, 11 (2017)

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Published in EPJ Quantum Technology: Mitigating radiation damage of single photon detectors for space applications

Quantum uplinks to Earth-orbiting satellites will necessitate single-photon detector technology that is robust to space radiation for the lifetime of the satellite. In this study, we experimentally assessed the effect of such radiation on a targetted selection of candidate detectors, with a focus on their impact to quantum key distribution. We then attempted to mitigate these effects, using thermal controls including deep cooling (during operation) and high-temperature annealing. Our results show that such techniques can maintain useful performance significantly beyond the one-year baseline lifetime.

E. Anisimova, B. L. Higgins, J.-P. Bourgoin, M. Cranmer, E. Choi, D. Hudson, L. P. Piche, A. Scott, V. Makarov, and T. Jennewein
EPJ Quantum Technology 4, 10 (2017)

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Published in Quantum Science and Technology: Airborne demonstration of a quantum key distribution receiver payload

This paper describes work I mentioned earlier. We successfully demonstrated quantum key distribution with signals transmitted from a ground station to a receiver on board a flying airplane. Our receiver (which is significantly upgraded in comparison to our prior truck demonstration) was designed and largely custom-built to have a clear path to flight on a satellite. Our demonstration illustrates the viability of such a payload.

C. J. Pugh, S. Kaiser, J.-P. Bourgoin, J. Jin, N. Sultana, S. Agne, E. Anisimova, V. Makarov, E. Choi, B. L. Higgins, and T. Jennewein
Quantum Science and Technology 2, 024009 (2017)

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QEYSSat moving forward

Some context:

I've been involved with the QEYSSat project, working on studies and prototypes, for the last 6 years. It's wonderful to see it selected as one of the two projects to receive funding, thereby allowing it to become an actual mission. Very exciting times!

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Our airborne QKD trials were mentioned in The Globe and Mail

September of 2016 was a busy month for a few reasons, one of these being the two weeks I was (with the rest of our IQC team) in Smiths Falls outside Ottawa conducting trials of our prototype quantum key distribution system. Ultimately this involved transmitting quantum signals from our ground-station quantum source to our receiver on a flying NRC aircraft—quite successfully, I might add. In the intervening time to now (and modulo one vacation to Australia and New Zealand) we wrote-up our results into a paper, the pre-print of which recently appeared on the arXiv.

At the same time (not coincidentally) an article about our work appeared in the Canadian newspaper The Globe and Mail—page 1 on Dec. 21, in our region—as well as the Waterloo Region Record (pg. 2, Dec. 22). You can read the online edition of the article.

So that's neat.

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