Subject: [Qirg] "deterministic" entanglement creation

From: Rodney Van Meter <[email-masked]>
Date: Sat, 7 Jul 2018 06:46:13 +0900

Ronald Hanson’s group published a paper just recently on what they call “deterministic” entanglement creation, using photons to entangle their nitrogen vacancy diamonds. What they are doing is taking a large number of probabilistic attempts, such that the probability of *none* of them succeeding is small, and calling that a “block” or “window”, then treating that window as their timeslot, which they call a “clock cycle”.

Their experiment attempts an entanglement every 5.5usec (180kHz), and they succeed 39 times/sec, so the success rate is 0.0002145, about 1/4600.

Then they create a 100 *millisecond* window, so that’s 18,000 attempts.

By my calculation, (1-0.0002145)^18000 = 0.02, so they have a 98% chance of having made an entangled pair during that time.

(Their calculation should be in the paper or supplementary material somewhere, this is my recreation.)

So, even if they succeed in the very first attempt, they then sit around and wait for the end of the 100msec clock cycle.

Sounds wasteful, and my approach from day one has been asynchronous protocols. but their claim is that synchronous will be a win in the end.

https://www.nature.com/articles/s41586-018-0200-5 <https://www.nature.com/articles/s41586-018-0200-5>
https://arxiv.org/abs/1712.07567 <https://arxiv.org/abs/1712.07567>

Thoughts?

		—Rod