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"Time Telescope" Could Boost Fibre-Optic Communications
An anonymous reader writes "A time lens can focus a chunk of time to a point, rather like a normal lens focuses light rays. Put two time lenses together and you can create what a Cornell University team calls a 'time domain telescope' which can magnify time. They sent a 2.5 nanosecond long light pulse, encoding 24 bits of information, into their time telescope. What came out on the other side was the same 24 bit pulse, but compressed into 92 picoseconds. Squashing more information into a light pulse could help to send more information via optical fibres."
"A time lens can focus a chunk of time to a point, rather like a normal lens focuses light rays."
no, its not LIKE a normal lens, it IS a normal lens. kind of like how "cloud computing" is the same client/ server model of decades past, a "times lens" is basically, uh, gee, a lens. but made sexy by introducing scifi fantasy terminology for the sake of grabbing attention
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
I'm used to these physics guys doing all kinds of crazy things with invisibility cloaks and such so I took the title to be a literal time lense.
After RTFA, the "time lense" is a frequency up-shifter. Still impressive, but not supernatural as I had hoped.
Not varying time but varying the speed of light over a pulse, still pretty cool but no need for the delorean yet.
Knowledge = Power
P= W/t
t=Money
Money = Work/Knowledge so the less you know the more you make
"A time lens can focus a chunk of time to a point,"
Since einstein we really know that space and time is the same thing, we really should just call it "squishing space", since time is really a measurement of a distribution of matter and energy, we've compressed the space (and hence the time).
"Time and space and gravitation have no separate existence from matter. ... Physical objects are not in space, but these objects are spatially extended. In this way the concept 'empty space' loses its meaning. ... Since the theory of general relativity implies the representation of physical reality by a continuous field, the concept of particles or material points cannot play a fundamental part, ... and can only appear as a limited region in space where the field strength / energy density are particularly high."--- (Albert Einstein, 1950)
...Ben Affleck starred.
We're boned.
So you were the guy who saw it.
If you have something that you dont want anyone to know, maybe you shouldnt be doing it in the first place -Eric Schmidt
.. I should know since I read them 70 picoseconds ago using my time telescope.
Doesn't that mean they compressed the amount of time it took light to travel that distance, and therefore changed the speed of light? Or was this simply a compression of the distance between the photons?
Neither. They've created a frequency upshifter (possibly one with interesting spectral properties to preserve the integrity of the encoded information, although the New Sensationalist article is so completely incoherent it's impossible to say if they have actually achieved that result) and given it the most dishonest, misleading name possible to confuse people, as posters above have noted, to grab attention.
They've got attention, but they haven't conveyed any information.
Blasphemy is a human right. Blasphemophobia kills.
Moving pulses through time has been done with electronic delay lines for about 80 years now. The theory and technology are well worked out, both in the time and frequency/phase domain. A friend of mine worked out an alternate theory around 1961, which left the theorists scratching their heads--- how could there be TWO optimum but different ways of squishing pulses? But it was true.
Anyway, you don't hear much about this technology as it's not a panacea of any sort. Any information you squeeze in time is going to undergo some unavoidable phase distortion-- not anything you want a lot of. And the inverse operation at the other end adds even more distortion. Yep, no free lunch, once again.
Does this mean Slashdot can pro-actively fix dupes without anybody seeing?
Table-ized A.I.
That means communications companies will soon be able to bring us 1000+ channels of infomercials and the same sports events for just $60 more per month, while at the same time capping our broadband usage at 2GB a month.
Seven puppies were harmed during the making of this post.
So, a normal lens will compress a series of pulses into a shorter series? How, exactly? I didn't realize that normal lenses worked by exciting the atoms in a waveguide with an infrared laser.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
They've got attention, but they haven't conveyed any information.
They've conveyed the information, but it's encoded in the 24 bits of the light pulse
Geology - it's not rocket science; it's rock science
In return, they could change ST opening speech with "Time, the final frontier". That would make a good part of the serie to get some meaning.
It's shifting the frequency into a shorter wavelength, without going through a chip.
From the article:
The Cornell team made their time lenses using a silicon waveguide that can channel light. An information-carrying pulse made from a series of
small laser bursts signalling digital 1s and 0s travels through an optical fibre and into the waveguide. As it enters, it is combined with another
laser pulse from an infrared laser. The infrared pulse vibrates the atoms of the waveguide, which in turn shifts the frequencies of the
data-carrying pulse before it exits the waveguide and passes into an optical fibre beyond.
When I logged in, I was greeted with "Did you know subscribers can see articles in the future?"
The abstract of the actual article is a little more informative, but still makes strange claims. I think they can compress a 10Ghz electrical signal into a 270GHz optical signal, with obvious ramifications in multiplexing, as you can then take 27 such signals at a time (theoretically).
You've missed the point. The "time telescope" is constructed of two of the frequency-changing lenses. The first lens disperses, the second converges, just like in a normal two-lens telescope. (Except the time telescope does it in frequency/time space instead of position space like your average telescope would.)
The result is a time-compressed pulse at the original frequency. The frequency-shifting is just part of the mechanism that gets this to work.
I can think of a myriad of uses ..|||..|.||. eady using it for that.
FLR
This is Slashdot. We know who Uhura is.
Karma fed to this user will be promptly burnt. Be warned; be wary.
I'll wait and see what happens.
I'm here for the experience, not the Hyperbole.
This new speed will totally revolutionize excuses for online gaming!
This reminds me of the movie Paycheck where they create a "time telescope" to see the future. I was surprised to see the post wasn't about seeing the future/past but rather the future of fiber optics. Certainly, I'm not going to complain if this eventually helps me download movies faster. Maybe at that speed, 2408 picoseconds faster is a big deal, like .1 second is a big deal to a 100m dash runner but irrelevant to a 1600m runner.
This is a complete oversell on a normal everyday phenomenon. This is a simple compression of a lightpulse, and has been done for a long time. Dispersion usually smears out a pulse, but can easily, compress the pulse. There is no "bending of time" here. Look up "Chirped pulse amplification" and also "Prism compressor", and maybe "soliton". First descibed in 1834 by John Scott Russell
don't cut it off www.mgmbill.org
Which means the IPO should be right around the corner.
The world's burning. Moped Jesus spotted on I50. Details at 11.
Perhaps all the information is there, but its been compressed by a time telescope to the point it is now a black hole. Since the information is within the event horizon, you cannot see it.
Go ahead. Disprove it.
The speed of light in a vacuum will never change. However, many different materials have different speeds of light. Just the earth's atmosphere has a slower speed of light than c. Normal lenses take advantage of the different speeds of light in glass versus air, and use that to their advantage to redirect the path of light. Time to take a physics class.
My blog. Good stuff (when I remember to update it). Read it.
So, the same as they do with origins science...
Peter predicted that you would "deliberately forget" creation 2000 years ago...
make it fancy sounding enough, and you can sell people air
read this:
http://en.wikipedia.org/wiki/Client-server
aka: cloud computing
"Client/server is a communications model. Cloud computing is a business model, a management model, a deployment model, etc... You might as well say "networking" is the real concept, and that fancy "cloud computing" is just a PHB term for "networking". Let's just call cloud "computer networking!""
so when the PHBs of the 1980s were deploying client/ server based systems, they were concerned with simply ethernet cable and routers? they weren't thinking at all about their business model, management model, or deployment model?
look, if i wave my hands fast enough, you can't see what i'm really talking about... zzz
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
Yes, but you may not like what you see. Lets just put it like this:
Last Night
You Beer
Girl Hideous
You Horny
Taxi Ride
Whale Ride
Light pulses of encoding?
I can't wait for the light pulses of devouring.
"Please describe how 'time-compressing' a waveform is different than frequency-shifting it"
If I frequency shift a waveform by a factor of 2, then the time compression is also a factor of 2. The article doesn't really mention it, but the frequency shifts in this experiment are much less than a factor of 2, but the time compression is from 2.5 ns to 95 ps, a factor of 27 compression.
This is a real time lens. A spatial lens works by imparting a quadratic spatial phase to light. Diffraction then causes the beam to focus due to the quadratic spatial phase.
A time lens works in analogy to a spatial lens by imparting a quadratic temporal phase to a light pulse. Propagation in a dispersive media then leads to the time compression.
The difficulty is it is very hard to impart a quadratic phase to short light pulses. The only real way to do it is nonlinear optics, which is where the (small) frequency shifts mentioned in the article come from.
Download my free songs!
...and he got modded up. "News for Nerds" used to mean the kind of nerds that were like Lisa Simpson and Martin Prince. Now the typical Slashdot nerd is more likely to be the Milhouse van Houten kind of nerd.
What happens when you take four Time Lenses and align them to be 90 degree angles to each other?
ONE MAN KNOWS THE TRUTH!
He even linked to a picture of the wrong Uhura :P
It pays to be obvious, especially if you have a reputation for being subtle.
And that's not Uhura.
Let's make a time machine with this technology already! :o
I think you're 83.33% correct.
Imagine a speech audio signal.
If you were to just compress the signal in time, the rate of speech would increase, but the frequency (pitch) would as well - it would sound like a chipmunk. This is what a simple resampling program would do.
On the other hand if you were to just frequency-shift the signal (say by heterodyning) then the rate of speech would be the same, but the pitch would change. This is what pitch-correction programs do.
If you do both in series and in opposite directions so the cancel, then the pitch remains the same but rate of speech is now increased. This is what fast playback programs (say for audio books) do.
The researchers figured out how to do the last to light using simple lenses. This could be useful because you can send the data down the same channel (like a frequency multiplexed fiber) as the original signal was intended for.
I could be very wrong but wouldn't shifting the frequency increase the latency of the signal since the original wavefront will be delayed to allow for the compression to happen? Maybe it wouldn't be a great shift (and so not really matter) but I was curious. Anyone with expertise in field care to comment?
"Why, Johnny Ringo. You look like somebody just walked over your grave." Doc Holliday, Tombstone.
Where's my goddamn flying car???
The other issue which nobody seems to be bringing up is that at the other end the light has to be uncompressed and corrected for errors so that it can be read properly. This takes time and essentially negates any savings. I suppose this sort of thing would be useful if vast distances were involved, but on the Earth, the distances are short enough where it's really a neat science trick rather than anything useful.
It seems like it could, provided that the lines can handle the bandwidth (which you claim, I'll take your word for it). As for the other end, if I got it right the process can be reversed to restretch out small chunks of the signal into something slow enough to be readable.
I wonder something though, can't they just send a bunch of parallel signals each at different frequencies instead of bothering with serialising the whole thing onto the same carrier? I mean it would use the same bandwidth in the end, so why bother making it all be on one carrier?
You just got troll'd!
If we really must have a car analogy, that's like making a packed 27-lane freeway going at 100 mph become a 1-lane road and still go at 100 mph. So for it to work they make the cars 27 times shorter in length.
You just got troll'd!
Uh, you guys are confusing me. Isn't there still going to be a bottleneck at the point between the output of the laser, and the lens? How do you actually compress anything with that bottleneck?
The article doesn't really mention it
Indeed: the article doesn't mention anything at all about what is actually going on here. It just throws out a confusing buzzword. Junk science reporting at its worst.
The analogy you describe makes sense to me, but unlike the idiots who decided to call this a "time lens" I know that the term will do nothing but confuse the ignorant, despite the relative elegance of the analogy.
There has to be some significant and permanent effect on the frequency dispersion, though, just as there is a significant and permanent effect on the momentum dispersion of a pulse due to a "spacial lens" (a term which I'm sure has never been seen outside of discussions of this badly misnamed analogy). Liousville's Theorem insists upon it.
So while I guess it is possible that the centre frequency of the pulse isn't changed, there are going to be huge effects on the overall frequency structure due to the "temporal focusing".
So why not call this a "frequency lens" in analogy to the more ordinary "momentum lens"? It would capture the elegant analogy, but be far less misleading to the innocent laypeople who are now being blindsided by the dishonest and stupid terminology of "time lens".
Blasphemy is a human right. Blasphemophobia kills.
Not quite. It's like you driving your 12' long car along the highway. When you drive through a tunnel your car (and you) come out perfect, functional, but only 3' long. After going through another tunnel you regain your original length.
The time lens terminology does seem a little sensational, but it is kind of descriptive. It's also very useful - we're not good at modulating light. We can completely saturate the bandwidth of an RF channel but we can only use a small fraction of the bandwidth of an optical signal. This type of device lets you upsample your slow, crappy modulation into something faster.
Next time you see someone with an article in Nature you might want to take slightly longer to try and figure out what he's actually done before you jump to the conclusion that he's "an #@&*$."
OMFG, that is the BEST Simpsons analogy EVER.
*rotflmao*
Do daemons dream of electric sleep()?
This means I can watch all six Star Wars Episodes in less than ten minutes.
Todos mis movimientos están friamente calculados
IANAP but based on reading temporal magnifier article the conclusion is that this is cool stuff that is intentionally being massively distorted by New Scientist in a UFO-craze way. Totally turns me off that mag now.
The paper is relatively readable even if you are not a physicist. Basically there is nothing spooky going on as New Scientist would say. The researchers developed a way to greatly stretch a short signal to a long one, is all.
The problem as stated in the Nature abstract, is that the science of photonics delivers such super-high speed signals that electronics are not fast enough to cope, you'd need a computer built of optical circuits. So this is a hybrid photonic and electronic circuit that delivers the next level of sophistication in enabling people to handle high speed signals.
Older ways of analyzing brief signals are limited to signals of low bandwidth, or they only work on repetitive ones, or they are hard to read out quickly. For example you could take a short signal and spread parts of it across several different detectors in space, but that isn't very good.
The researchers used a totally different approach. In information communications science it appears there is an equivalence between the way a signal can disperse diffracts in space and how it disperses in time. One method called four wave mixing (FWM) can be used to stretch out the signal in time.
The scientists at Cornell used FWM but introduced a non-linear process that stretches the signal much more. The process is not just linear, it is quadratic so you can get exponential amounts of stretching.
They call this device a a time lens, as it operates in the time domain, the way a normal optical lens works in the spatial domain. It even has a similar quality they call its focal length. The "lens" can "magnify" (stretch) a very short signal into something long enough that it can be analyzed.
It also can be used in reverse to "shrink" (compress) a signal in time similarly. For example as a demonstration they created a sequence of pulses each 33 picoseconds in length and then compressed each pulse in the sequence to only 4.5 picoseconds in length using their time lens as a compressor.
The lens can be set at different magnification factors, and the maximum they achieved so far is a world record, 520 times magnification. It is very cool and the idea of usign an optical paradigm in the time domain to create a circuit that is a "time lens" seems to be a very powerful technique that will generate a lot of further advances and applications.
How is this flamebait?!?!
This is an interesting idea, but they note that you will need to decompress the stream at the other end. This means that unless you can multiplex the light and have multiple compressed streams sharing the same channel, you won't see any performance improvement. You are still limited to transmitting/receiving at a fixed rate; its just that the bits take a shorter time to transit the pipe.
Are there any losses that are proportional to the time a light pulse spends in a fiber? I'm pretty sure its just related to distance.
Mon chien, il n'a pas du nez. Comment scent-il? TrÃs mauvais!
Who said that?
He just did it while he was sober.
bickerdyke
I was unfortunate enough to have to watch this movie. Let me just say that Ben Affleck and this movie were made for one another. I can't imagine any other actor as a better fit for the role.
Most informative comment I've seen today, and I'm fresh out of modpoints.
What a depressingly stupid machine.
So they've discovered WinZip for laser pulses? That's what this sounds like to me... 2.5 nanosecond / 24 bit laser pulse goes in, 92 picosecond / 24 bit laser pulse comes out, with the same information encoded. It's lossless compression, basically.
Yes, the Time Tunnel project has begun!
If this is what the researcher figured out how to do, this is truly a time lens.
No ascii art.