8 ms·
Water-based circuit concept switches much faster than semiconductors
- amelius 4y agoHow can you make logic gates with this?
- dtgriscom 4y agoAgreed: how is this a "circuit"? How does the output drive the input of another one of these? It looks like this is just "shine a laser at a material to change it, and then use another laser to detect the difference."
- adrian_b 4y agoYou can describe any transistor with the same words as "shine a laser at a material to change it, and then use another laser to detect the difference": "apply a voltage at a device to change it, and then use another voltage to detect the difference (i.e. to detect if a current passes)". This is an optical switch, like a transistor is an electrical switch. An optical switch that is not very efficient, because the transmission is varied only between 100% and 80%, but one that is very fast. It can be used in THz range mixers and oscillators.
- amelius 4y agoThat's not a good argument. I could say: "Put a voltage over a resistor and use an ammeter to detect the difference" and make a resistor look like a transistor which it clearly isn't.
- nullish_signal 4y agoThe comment above yours said "and then ... detect the difference", implying sequential action and a real change of state - not simultaneous action+measure. """Because the laser pulse is so fast, the water can switch states in a matter of picoseconds, which are trillionths of a second.""" Although after reading, I must agree that the time-scale feels quite ridiculous!! (EDIT: RE: "Capacitors can't be logic gates" below - Maybe. But if 1+0=1, and 1+1=2, then surely differentiating 0/1 vs 2 on the output creates an AND gate?) (I am "posting too fast" with 3 posts in the last hour. Sorry :)
- amelius 4y ago> implying sequential action and a real change of state - not simultaneous action+measure. Ok, replace resistor by capacitor :) I.e., run a current through a capacitor, then (some time later) measure the voltage over it. I don't recall anyone actually creating logic gates using capacitors only.
- adrian_b 4y agoNot at all. In the definition of any controlled switch, e.g. transistor, optical switch or any other kind, it is essential that there are two distinct quantities, e.g. voltages or light beams, one that controls the output state and one that provides power to the output circuit. A resistor corresponds to a tinted window, not to an optical switch.
- amelius 4y agoOk, with that addition, here is another analogy: I have one battery that I use to charge a capacitor. Then I have another battery in my voltmeter, which I use to measure the voltage over the capacitor. How does this make it possible to build logic gates with capacitors? Instead of trying to generalize the principle, why don't you explain how you can make logic gates using the technology of the article? And how can you tie these logic gates together without the signal becoming weaker between input and output?
- dtgriscom 4y agoNote that in a transistor, "another voltage to detect the difference" can be used to trigger another transistor, and so on. Until the laser reading the state of water can itself trigger a write in another water "switch", this is just a cute dead-end phenomenon.
- rohan1024 4y agoIf we do end up creating a processor using this, I wonder if it will need liquid cooling.
- jimmySixDOF 4y agoPresumably they can use cold water in the jets which itself chills the space. Nice fringe benefit If It Scales.
- ohyes 4y agoYou need to cool the laser presumably, I wouldn’t use water for that, however.
- cmmeur01 4y agohttps://en.m.wikipedia.org/wiki/Fluidics https://en.m.wikipedia.org/wiki/Fluidics
- amelius 4y agoThat doesn't involve a laser like in the article, and is probably much slower. I don't think you can get Terahertz speeds by just using Newtonian physics on water.
- ilaksh 4y agohttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC2860314/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2860314/ Microfluidic Photonic Integrated Circuits?
- mannykannot 4y agoWhile the paper's keywords list includes both microfluidics and photonics, nothing about the device is anything like an opto-fluidic logic gate. The laser is used to measure properties of cells suspended in the fluid, with the output light signal being processed by conventional photonics.
- danuker 4y agohttps://en.wikipedia.org/wiki/Optical_computing https://en.wikipedia.org/wiki/Optical_computing > To replace electronic components with optical ones, an equivalent optical transistor is required. This is achieved using materials with a non-linear refractive index.
- adrian_b 4y agoLike with any switches, by connecting them in series and in parallel. Nevertheless, it is unlikely to use such optical switches for logic gates. The most likely application for them is in mixers and oscillators.
- dtgriscom 4y agoBut that's the problem: how does the "output" of one of these switches drive the "input" of the next one?
- adrian_b 4y agoThe question was how to make logic gates. There is no impediment for making a complex logic gate by an arbitrary series-parallel connection of the output light beams. The output of such a logic gate cannot be connected to the input of an identical logic gate, because the input and the output light beams have different frequencies. This is a problem common for many kinds of optical switches. It is likely that any conversion circuit that could be inserted between two such logic gates would be much slower than them, negating any speed advantage. This does not really matter, because such optical switches are not intended for making logic circuits.
- bondarchuk 4y ago>Next, a short but powerful laser pulse is fired into the water jet. This bumps electrons out of the dissolved salts, essentially boosting the conductivity of the water. A second laser can read back what state the water is in, providing the “on” and “off” options of an existing transistor. Sounds like an optical computer much more than a water computer (compared to e.g. microfluidics), and it's much less surprising that an optical switch would switch fast.
- Waterluvian 4y agoSo the water is the copper and the laser is the electrons?
- musingsole 4y agoWater is the conductor, yes. Electrons are still the electrons -- excited by or measured by laser
- bee_rider 4y agoThis is really going to mess up the hydraulic analogy.
- nullish_signal 4y agoIt's Water carrying Water, all the way down
- skykooler 4y agoIt’s like someone turned https://xkcd.com/2571/ https://xkcd.com/2571/ into reality.
- djtango 4y agoSo I've been out of Chemistry for the best part of a decade but I think the novel part of this is exploiting the fact that water based solvents are insanely efficient at propagating charge. Here is some reading I think nay be relevant[0][1][2] but tldr thanks to the miracle of hydrogen bonding, protons/electrons can "transfer" through water by an extremely fast chain reaction of proton association/dissociation - thereby circumventing diffusion as a transfer mechanism. Laser is a useful interface because lasers can be controlled digitally and provide a convenient way of ionising the solution, but this seems like quite a cool hack exploiting the properties of water to me. [0] https://en.m.wikipedia.org/wiki/Grotthuss_mechanism https://en.m.wikipedia.org/wiki/Grotthuss_mechanism [1] https://www.sciencedirect.com/topics/engineering/grotthuss-mechanism https://www.sciencedirect.com/topics/engineering/grotthuss-m... [2] https://pubs.acs.org/doi/10.1021/jz501235y https://pubs.acs.org/doi/10.1021/jz501235y
- BiteCode_dev 4y agoSo it's not water that makes it fast, it's laser.
- solardev 4y agoWet, fast, excited laser.
- ghastmaster 4y agoThis is equivalent to saying, "So it's not the semiconductor that makes it fast, it's the electrical current." The medium that is changing conductivity is water in this case, and it is able to do it much much faster. That said, the system involves a laser that adds to the ability to switch quickly. "Because the laser pulse is so fast"
- f1shy 4y agoIs the transistor driving the laser very fast...
- readthenotes1 4y agohttps://youtu.be/ZfKGC3LFyFA?t=353 https://youtu.be/ZfKGC3LFyFA?t=353 Predicted in Rollerball
- madengr 4y ago
- greenbit 4y agoIodine in water ionized on the picosecond scale, by laser pulse. Would be mildly surprised if that didn't happen that fast. I guess the interesting twist is that the medium is flowing liquid. How long does this state last? If one were to, say, write a series of bits into the upstream side of the flow, how many such bits could you recover downstream? The potential I see here is possibly a delay line for THz band signals, not so much the basis for logic for a 1000GHz CPU. But delay lines are darned useful things.
- vlovich123 4y agoIt’s been a while since I did circuits. What are delay lines used for?
- jacquesm 4y agoStorage, synchronization and signal recovery off the top of my head.
- surfpel 4y agoIn RF, delay can be used to attenuate signals. So filtering of signals.
- ajb 4y agoEarly computers used delay lines as memory https://en.wikipedia.org/wiki/Delay-line_memory https://en.wikipedia.org/wiki/Delay-line_memory
- evancox100 4y agoAlso sometimes you may want to apply skew/deskew to signals, finely tune the arrival time of two or more signals, etc.
- throwawaylinux 4y ago> Because the laser pulse is so fast, the water can switch states in a matter of picoseconds, which are trillionths of a second. This translates to potential computer speeds in the terahertz (THz) range – that’s 1,000 GHz, which is far faster than any existing semiconductor can switch. Picoseconds means under 1000GHz. 1ps would be 1000GHz. Transistors can switch in picoseconds. The fastest basic bulk silicon ones hundreds of GHz as far as I know. More exotic ones I'm sure could be made a lot faster. So exactly how much faster is this water based switching device than a transistor? Hopefully the author was not under the impression that transistor switching speed was on the order of CPU clock frequency.
- adrian_b 4y agoAccording to the article, they have demonstrated the generation of a signal with the frequency of 3 THz, and the switching time is under 200 fs (exponential edge with a time constant of 70 fs).
- f1shy 4y agoYes... and how is the laser driven? Of course, fast transistors... There are transistors circuits that go into THz.
- adrian_b 4y agoThat is completely false. The shortest laser pulses are much shorter than any pulses that can be generated with electronic devices, and they are generated by various optical means. There are no transistor circuits that go into THz, but only into hundreds of GHz, and at those high frequencies they are not pulse circuits, but amplifiers or oscillators. A review of potential future transistors that will go into low THz: https://www.mdpi.com/1424-8220/19/11/2454 https://www.mdpi.com/1424-8220/19/11/2454
- f1shy 4y agoR u sure? https://ieeexplore.ieee.org/document/8240463 https://ieeexplore.ieee.org/document/8240463 For that matter, the laser controlled by other means will not be switched at total discretion, but at a fixed rate. Not different than an oscillator.
- phkahler 4y ago>> Because the laser pulse is so fast, the water can switch states in a matter of picoseconds, which are trillionths of a second. This translates to potential computer speeds in the terahertz (THz) range – that’s 1,000 GHz, This in not comparable to transistors in a computer. Transistors use charge (electrons) to switch current (electrons) in order to build boolean gates and logic circuits. Those lasers are probably not optically controlled, and even if they were and could be made into optical logic circuits, their speed will be limited by their size and the speed of light.
- sudosysgen 4y agoLasers are electric and the water is used to carry a current, so you presumably power the lasers using the current in the water to make gates.
- bagels 4y agoWhich is more of a limit of clock speed, signal propagation or transistor switch time? I know heat dissipation is a large factor.
- thechao 4y agoCompactness and timing. I don’t know why picosecond switching is a big deal, here? A 3Ghz part with a transistor depth of 40 would require a top end switching rate of 8 picoseconds — and that’s really going to make PD unhappy, as it’d leave no timing margin. At best, this tech is 2–4x faster than the device in your pocket; it’s probably slower, knowing the timing rates of some of the analog-on-digital parts being shipped, right now.
- MayeulC 4y agoYes, I'd say it's switching losses driving power dissipation, mostly, but also the amplification factor (often written as 60mV/decade). Bipolar transistors are still better at that. I haven't read the article yet, but I can imagine a chip with watercooling microfluidic channels, possibly also used to transmit informations (kind of like hormones in the bloodstream). If it is useful as a computing medium why not? Would it make a good waveguide too?
- xkcd1963 4y agoDoes it evaporate?
- 7speter 4y agoThis makes me think of the water pipe puzzles from bioshock, but I guess it isnt supposed to.