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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.
...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.
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.
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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
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
Hrm....
Don't you mean time dilation?
"I am the king of the Romans, and am superior to rules of grammar!"
-Sigismund, Holy Roman Emperor (1368-1437)
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
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
"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.
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...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!
If it makes you feel better you can use such sophistry to claim they are the same thing. I'm not clear if you're being intentionally dense or just don't understand.
My point about just calling it "computer networking" is that it certainly is "computer networking". It's also "client server". And it's also "cloud computing". They all add meaning. It's not even that hard to grasp.
I'm using "client server" if I have a few hundred netapps in a computer room and use NFS to expose the data to my client machines. I'm not using cloud computing.
If I use Amazon's storage resources and Amazon's virtual computing infrastructure to host my services then I'm using the cloud.
Of course it's client/server. Almost any system that uses a network could be termed client/server, even e.g. P2P. What's your point?
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.
It's really the ecosystem of client/server systems provided by many different vendors which together form "the cloud". That's the other part of this - there was originally supposed to be one cloud. Meaning it would be Internet based. Now it's getting diluted and people are applying the same concepts inside a private network.
But again, considering these are networked systems "client server" seems a bit redundant. Like calling client/server "computer networked client/server".
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.
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?
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 #@&*$."