3 ms·

Yes, but all existing photonic platforms use post-selection which is even more clearly exponentially lossy. Although this could be solved with a deterministic s

Yes, but all existing photonic platforms use post-selection which is even more clearly exponentially lossy. Although this could be solved with a deterministic single photo source if one can be found. Photonic quantum computing is an especially funny post-transistor paradigm because classical photonic computing is also quite attractive.

abdullahkhalids 3y ago
If you read the linked article, it explains how to avoid exponential loss on post-selection. > Imagine you can toss coins, and you need to generate 20 coins showing Heads. If you repeatedly toss all 20 coins simultaneously until they all come up heads you’d typically have to do so millions of times before you succeed. This is even more true if each coin also has a 20% chance of rolling off the table (akin to photon loss). But if you can toss 20 coins, set aside (switch out!) the ones that came up heads and re-toss the others, then after only a small number of steps you will have 20 coins all showing heads. This large gap is fundamentally why the first whammy is not relevant: To generate a large photonic entangled state we begin by probabilistically attempting to generate a bunch of small ones. We then select out the success (multiplexing) and combine successes to (again, probabilistically) generate a slightly larger entangled state. We repeat a few steps of this. This possibility has been appreciated for more than twenty years, but hasn’t been done at scale yet because nobody has had a good enough optical switch until now.
- alpineidyll3 3y ago
  Haha a self promotional blog post without any experimental data from a lab self-interested in the technology is somehow not persuasive to me. There is no way to add entangled particles to an entangled photon state without new light matter interaction which may (and almost certainly) bring decoherence. Ie to claim a good enough switch is possible is a claim demanding a ton of evidence, and there is none right now. Ofc I would be thrilled to see it work! But explaining a scheme in back of the envelope fashion and measuring it are two vastly diff things.

abdullahkhalids 3y ago

If you read the linked article, it explains how to avoid exponential loss on post-selection. > Imagine you can toss coins, and you need to generate 20 coins showing Heads. If you repeatedly toss all 20 coins simultaneously until they all come up heads you’d typically have to do so millions of times before you succeed. This is even more true if each coin also has a 20% chance of rolling off the table (akin to photon loss). But if you can toss 20 coins, set aside (switch out!) the ones that came up heads and re-toss the others, then after only a small number of steps you will have 20 coins all showing heads. This large gap is fundamentally why the first whammy is not relevant: To generate a large photonic entangled state we begin by probabilistically attempting to generate a bunch of small ones. We then select out the success (multiplexing) and combine successes to (again, probabilistically) generate a slightly larger entangled state. We repeat a few steps of this. This possibility has been appreciated for more than twenty years, but hasn’t been done at scale yet because nobody has had a good enough optical switch until now.

alpineidyll3 3y ago
Haha a self promotional blog post without any experimental data from a lab self-interested in the technology is somehow not persuasive to me. There is no way to add entangled particles to an entangled photon state without new light matter interaction which may (and almost certainly) bring decoherence. Ie to claim a good enough switch is possible is a claim demanding a ton of evidence, and there is none right now. Ofc I would be thrilled to see it work! But explaining a scheme in back of the envelope fashion and measuring it are two vastly diff things.