I took a look at the original paper. I think it follows from the fact that they experiment used 10 qubits, the tenth Fibonacci number is 55 (depending on how yo

I took a look at the original paper. I think it follows from the fact that they experiment used 10 qubits, the tenth Fibonacci number is 55 (depending on how you count), and each "tick" in the experiment lasted 100 ms. Put those together and each experiment has to be exactly 5.5 seconds long. (They ran ~100 repeats per condition, plus 10,000 simulations). I'm admittedly not 100% (Nature papers are terse and heard to read even in one's own field and this is far away from mine), but it makes a certain amount of sense.