5 ms·

- "The new gates performed at speeds of less than 100 femtoseconds, which is roughly 1 million times as fast as electronic gates" Electronic gates switching at

- "The new gates performed at speeds of less than 100 femtoseconds, which is roughly 1 million times as fast as electronic gates" Electronic gates switching at 10 MHz?

tiagod 4y ago
I remember this exact issue in the last HN front-page article about optical gates, weeks ago...
- airstrike 4y ago
  Do you have a link? Would love to read that
amelius 4y ago
1 femtosecond = 1e-15 seconds.
- perihelions 4y ago
  Right, so 100 fs = 1e-13 seconds. And a million times slower than that would be 1e-7 seconds, or (10 MHz)^{-1}.
  - greenbit 4y ago
    Commodity PCs were running 10MHz clocks by 1988, weren't they?
    - tiagod 4y ago
      The point is they now run at several GHz, so their comparison is off by orders of magnitude.
oh_my_goodness 4y ago
Yeah, they're off by a factor of 1000. There are other serious technical errors in the piece too. For example they say "because photons move at the speed of light and electrons don't" ... which is irrelevant because electronic signals do move at the speed of light. The most serious problem is missing context. It's been known for decades that you can build shockingly fast optical switches and even amplifiers. A hundred fs is fast but not unique. The problem is how to connect these devices in a complicated circuit without putting nanoseconds of waveguide in between. Unfortunately 1 ns is 1,000,000 fs. So in telecom, where you're just going a long way in one direction, optical amplifiers with multi-THz bandwidth have dominated transport since the 1990s. But in computers, no.
- blep_ 4y ago
  Electronic signals also do not move at the speed of light: https://en.wikipedia.org/wiki/Velocity_factor https://en.wikipedia.org/wiki/Velocity_factor
  - teddyh 4y ago
    Yes they do. It’s just that the speed of light differs slightly depending on the medium.
    - ilyt 4y ago
      - oh_my_goodness 4y ago
        As you know from reading the link, electrical signals and light are both EM waves and both travel at the speed of light in the medium they're propagating in. The copper isn't the medium. The EM waves are almost entirely outside the copper. The medium is the insulator (for a cable) or the glass (for an optical fiber). Sorry to repeat all this material from the link, which you've definitely already read.
      - dang 4y ago
photochemsyn 4y ago
Probably just a miscommunication. The actual improvement is more like 10K times, but this moves from the 'gigahertz range' to the 'petahertz range' which differ by 1e6. > "Since light oscillates so fast (roughly a few hundred million times per second), using light could speed up electronics by a factor of roughly 10 000 as compared to computer chips,” says Tobias Boolakee, a laser physicist in Peter Hommelhoff’s group at the FAU and the first author of a study in Nature on the new gate." (2022) https://physicsworld.com/a/logic-gate-breaks-speed-record/ https://physicsworld.com/a/logic-gate-breaks-speed-record/
- oh_my_goodness 4y ago
  Light oscillates much, much faster than a few hundred million times per second. Take 1 micron wavelength. At a speed of 3e8 m/s, 1 micron light oscillates 3e8/1e-6 = 3e14 times per second. Three times ten to the fourteenth power. For anybody who doesn't juggle large numbers every day, a hundred million is 1e8. Ten to the eighth.
  - photochemsyn 4y ago
    Maybe they meant trillions? The 10,000 times faster number seems correct though, as fiber optic carries light at ~200-300 THz and 10 GHz is the electronic standard at present.

- "The new gates performed at speeds of less than 100 femtoseconds, which is roughly 1 million times as fast as electronic gates" Electronic gates switching at 10 MHz?

tiagod 4y ago

I remember this exact issue in the last HN front-page article about optical gates, weeks ago...

airstrike 4y ago
Do you have a link? Would love to read that

amelius 4y ago

1 femtosecond = 1e-15 seconds.

perihelions 4y ago
Right, so 100 fs = 1e-13 seconds. And a million times slower than that would be 1e-7 seconds, or (10 MHz)^{-1}.
- greenbit 4y ago
  Commodity PCs were running 10MHz clocks by 1988, weren't they?
  - tiagod 4y ago
    The point is they now run at several GHz, so their comparison is off by orders of magnitude.

oh_my_goodness 4y ago

Yeah, they're off by a factor of 1000. There are other serious technical errors in the piece too. For example they say "because photons move at the speed of light and electrons don't" ... which is irrelevant because electronic signals do move at the speed of light. The most serious problem is missing context. It's been known for decades that you can build shockingly fast optical switches and even amplifiers. A hundred fs is fast but not unique. The problem is how to connect these devices in a complicated circuit without putting nanoseconds of waveguide in between. Unfortunately 1 ns is 1,000,000 fs. So in telecom, where you're just going a long way in one direction, optical amplifiers with multi-THz bandwidth have dominated transport since the 1990s. But in computers, no.

blep_ 4y ago
Electronic signals also do not move at the speed of light: https://en.wikipedia.org/wiki/Velocity_factor https://en.wikipedia.org/wiki/Velocity_factor
- teddyh 4y ago
  Yes they do. It’s just that the speed of light differs slightly depending on the medium.
  - ilyt 4y ago
    - oh_my_goodness 4y ago
      As you know from reading the link, electrical signals and light are both EM waves and both travel at the speed of light in the medium they're propagating in. The copper isn't the medium. The EM waves are almost entirely outside the copper. The medium is the insulator (for a cable) or the glass (for an optical fiber). Sorry to repeat all this material from the link, which you've definitely already read.
    - dang 4y ago

photochemsyn 4y ago

Probably just a miscommunication. The actual improvement is more like 10K times, but this moves from the 'gigahertz range' to the 'petahertz range' which differ by 1e6. > "Since light oscillates so fast (roughly a few hundred million times per second), using light could speed up electronics by a factor of roughly 10 000 as compared to computer chips,” says Tobias Boolakee, a laser physicist in Peter Hommelhoff’s group at the FAU and the first author of a study in Nature on the new gate." (2022) https://physicsworld.com/a/logic-gate-breaks-speed-record/ https://physicsworld.com/a/logic-gate-breaks-speed-record/

oh_my_goodness 4y ago
Light oscillates much, much faster than a few hundred million times per second. Take 1 micron wavelength. At a speed of 3e8 m/s, 1 micron light oscillates 3e8/1e-6 = 3e14 times per second. Three times ten to the fourteenth power. For anybody who doesn't juggle large numbers every day, a hundred million is 1e8. Ten to the eighth.
- photochemsyn 4y ago
  Maybe they meant trillions? The 10,000 times faster number seems correct though, as fiber optic carries light at ~200-300 THz and 10 GHz is the electronic standard at present.