Slashdot Mirror
Quantum Holography
Buzz Skyline writes "Physicists succeed where psychics fail. Researchers from Boston University propose a quantum holography system that can construct 3d images of objects sealed in closed containers. Could it lead to quantum luggage scanners at the airport?"
Great! Now we'll be able to tell Schroedinger once and for all whether his stupid cat is dead or not.
Nathan
The article seems to imply that you need a specially constructed sphere to make this work. One that lets light in at a specific point, and allows no light out. It also is built in such a way to detect when a photon hits the inside surface. Just take a look at the diagram.
So unless someone is stupid enough to try and sneak a bomb onto a plane in one of these spheres, it's not much use to the security guards.
"Tomorrow's forecast: a few sprinkles of genius with a chance of doom!" - Stewie Griffin
Would spare them from the dreaded Dirty Laundry DoS attack frequently perpetrated at Customs. =)
- billn
Why does everybody still have airport security on their brain still? Think if this can be used in medicine.
No more exploratory surgery. Quickly detect cancer growths.
Perhaps somone will be able to make a pair of X-RAY specs that actually work! :)
...but I get to check two boxes in Slashdot Buzzword Bingo. Just a few more to go....
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
http://www.sciam.com/explorations/061796exploratio ns.html
http://users.ox.ac.uk/~jsw/Schroedinger.html
The man who trades freedom for security does not deserve nor will he ever receive either. - Benjamin Franklin
. . .
propose to create holographic images of objects concealed in a spherical chamber. Ideally, a small opening in the chamber wall permits light to enter, but lets no light out. The photons in a beam of light directed through the hole scatter from the enclosed object, and ultimately strike the inner wall of the chamber (see figure).
So it's not sealed, but a small opening. I dunno if I want people making holes in my luggage.
1q2w3e4r5t6y7u8i9o0pqawsedrftgthyjukilo;p'azsxdcf
"Look! I think its a bomb!"
"Sure does look like one..seize her!"
Five minutes later.
"There was no bomb in here..WTF?"
"It would have been in there if we hadn't looked!"
Job? I don't have time to get a job! Who will sit around and bitch about being broke and unemployed then?
Ah, but what if I knew what it looked like before setting the whole thing up? If my hologram looked like the original, as I saw it in the first place, then is this not accurate?
I suppose you could argue collapsing wave functions and quantum probability, but I'd think that was pushing it, no?
"They do not preach that their god will rouse them, a little before the Nuts work loose." Kipling, 'The Sons of Martha'
Correct link with no space!
The man who trades freedom for security does not deserve nor will he ever receive either. - Benjamin Franklin
I don't believe so. I personally feel the problem with airport security is not the type of equipment used, but the incompetence of some of the security people employed there. You've heard the security breach stories on the news.
"What is that, a hairdryer with a scope on it ?... That looks okay, keep it moving". "Some sort of bowling ball candle ? That's fine, just... we don't want to hold up the line, don't hold up the line"
Jerry Seinfeld on Airport Security
Think for a moment which is worse: to have the government searching you in broad daylight, where everyone can witness, or to give that government the power to search you at any time it wishes, with neither consent nor notification?
I for one do not feel the same way. In my mind, this kind of "secret" searching is just as degrading, and does not provide as much protection for the citizen.
-Justin
That's enough posting for now lads, there're trolls afoot.
I don't really understand quantum entanglement but . . .
Couldn't you use it to communicate instantly over any amount of distance?
Imagine:
You are at point A (say, earth) and I'm at point C (say, a spacecraft) and we have a buoy, at point B, precisely half way between us. Let's say that you and I are one light-year apart, and that buoy has been splitting a beam of photons between the point where I am and the point were you are for the last six months.
You have a photoreceptor oriented 90 degrees out from the beam, and I have a mirror at 45 degrees, hooked up to a solenoid. I type you a message in morse code on a switch that controls current to the solenoid. You see it in real-time.
I'm sure that either 1. there is a really good reason why this won't work in theory or 2. someone else has proposed it.
Can someone give me a reference either way?
-Peter
So unless someone is stupid enough to try and sneak a bomb onto a plane in one of these spheres, it's not much use to the security guards
Reminds me of the old joke...
In the early days of Rocket Science(tm), they were trying to figure out how to protect the astronaut from acceleration. So they hired one of the leading physicists of the day to investigate.
A month later, he came back with a solution. He got up in front of the NASA bigwigs, and said, "First, assume a perfectly spherical astronaut..."
Fascism starts when the efficiency of the government becomes more important than the rights of the people.
You can get an idea of what something is shaped like in more conventional ways. Like X-ray.
What is really impressive is that they can see what the surface of a flat object, like a photograph, looks like. Neat!
-Peter
First, I'd like to point out that quantum computation and quantum encryption are two almost completely separate concepts. Quantum encryption is based on the fact that quantum states cannot be measured without altering. The most common example is the polarization of a photon, but it will work for any quantum state, so long as there exist, effectively, two unique states that can transmit the data.
Quantum computation, however, is much more complex and much more interesting. Quantum computers are based on the concept of quantum entanglement, the ability of a quantum state to exist in a superposition of all of its mutually exclusive states: It's a 1 and a 0. However, this is not as easy to use as one might think. While it's true that if you have n quantum logic gates you have the ability to input 2^n data values simultaneously (as opposed to only 1 piece of data if you have n digital logic gates), this is not going to be the end of classical computing for a few reasons. First, quantum computers have to be perfectly reversible. That means for every output there's an input and vice versa. And there has to be no way of knowing the initial states of the data. You don't process data, you process probabilities in a quantum computer; if you know exactly what any one value is throughout the computation, you can find out all of the values: the superposition ends and you're stuck with a useless chunk of machinery. This means YOU CAN ONLY GET ONE RESULT FROM ANY QUANTUM COMPUTATION, THE END RESULT. You can't see what the data in the middle is or the computer becomes useless. (Landauer's principle makes heat loss data loss. When your processor gets hot, it's losing data. If the same thing happened to a quantum computer, it wouldn't be quantum anymore.) Decoherence is what happens when you randomly lose data to the environment by design, not by choice, and the superposition ends. This is bad for Q.C. Oh, and quantum computers can only do *some* things faster, like prime factorization and discrete logarithms. Not multiplication or addition. Plus, the circuits that would do basic arithmetic would be bigger and slower than what you've currently got.
So what does this all mean? It means that quantum computers are going to provide some advantages (real quick big number factorization), and some disadvantages (that whole RSA standard). The most realistic initial use of quantum computers will be as add-ons to existing super-computers to resolve certain types of NP-Complete headaches that regular math can't simplify yet. At best they will someday be an add-on to your PC; but they will never replace the digital computer.~
If you want more info, check out ahttp://www.qubit.org, it's got some decent tutorials.
if that is true then it is not real entagelment. I should not have to read what happens to photon a and compair it to photon b to if they were actualy entagled, photon a should tell me what photon b is doing.
I am the Alpha and the Omega-3
...a new, more efficient porn acquiring method for geeks - because most clothes are not entirely opaque and some light gets to the skin, can this be used to acquire 3D nude holograms of fascinating females that pass by?
Everyone who makes generalizations should be shot.
Wow, all the ideas going through my head are just amazing me. Thieves could use this to see if someone's in a house, and slashdotters could use it to broadcast live porn!
Here is a link to the
actual paper itself. It's a PDF file though
Yeah yeah, it's all funny but it ticks me off that nobody is pointing out that The principle illustrated in Schroedingers "cat" thought experiment are NOT THE SAME as the Heisenberg Uncertainty Principle. In fact, it ticks me off that nobody knows what the Uncertainty Principle is really about and people constantly confuse it with the whole indeterminate quantum particle state and whether does in fact create quantum indeterminacy on the macro scale (if a tree falls in the forest...) issue. Heisenberg's Uncertainty Principle establishes a mathematically defined absolute uncertainty balanced between the momentum and position of a quantum scale particle. The corresponding thought experiment would be the gamma ray microscope.
It Is the Nature of Information to Transgress Artificial Boundaries
OK, So we put a suitcase into one of these things at an airport, et VIOLA!...
:-)
... a hologram of a suitcase! Methinks this one will need work before it replaces the good ol' Airport Xray machine.
Of course quantum entanglement is also how "they" propose to achieve the matter-transporter, so forget looking inside the luggage, we can just send it on ahead
Enjoy Y2K? Roll-on Year 2037!
a tad OT, but: Text search for GUENTER NIMTZ on http://www.pbs.org/wgbh/nova/transcripts/2612time. html
Similar, but not the same . . .
The given example apparatus would not be a practical device in any way. It needs a way to allow photons in, and could just as easily allow photons out; additionally, the inner surface of the sphere needs to be a photon detector with very precise timing. It doesn't see anything a camera inside the sphere couldn't see.
This is about exploring quantum entanglement. When lasers were invented, nobody knew what to do with them. Everybody thought "Death ray!" which was pretty silly in retrospect; that's a minor application. Then, bit by bit, they found thousands of ways to apply them that revolutionized all sorts of practical devices and allowed entirely new ones.
Developing this would be breaking old rules about what is and isn't possible, and though it's hard to guess exactly what it's good for, you can bet it'll be good for some amazing new technologies.
Holography basics (aimed at Highschool students level).
Books and information on Holography
Some more holography Theory>
--- Metamoderating abusive downgraders since my 300th post.
If the cat meows, would that break the uncertainty principle?
Does it make you happy you're so strange?
Knowing the particles are entangled is extra information. If I know bits A and B are either both 0, or both 1 (fully entangled), and I observe bit A to be 0, I know B is 0. No information or state is transferred between the two particles after the initial entanglement.
This can still be performed if, for example, bits A and B are on different HDs, and I ship one across the country. Suddenly, by reading one, I can tell someone across the country what they will read at the address where their bit is on the disk.
IT JUST CREATES A 3D IMAGE OF A 3D IMAGE!
-theres no X-Ray vision here! For luggage they would be able to say "I think its a suitcase"
-it does seem "spooky" though
-it does have potential uses that could be really cool. Remote surgery, biometrics, 3D video
"You're on my side and the dark side, like Lando Calrissian?" --Gimpy, Undergrads
Good lhord, did anyone actual read the damn article? Here's a clue: No.
The technology described will not scan your luggage, nor will it make body cavity searches obsolete, unless you have a spherical, photosensitive rectum.
Not a cure for cancer, or a replacement for a cat scan or MRI.
What the technology excels at is showing you what's inside a specially constructed sphere. This information could also be garnered with a sufficiently large hammer.
A cool physics party trick, and some interesting basic research. That's about it.
What were you expecting?
The idea is that since photons travel at the speed of light (duh), they don't experience "time", and can actually make a "choice" about the path they are going to take, so that an entangled pair of photons "agree" as to where they will be in the future. This has the affect of looking to us like there is an "instantaneous transmission" of information from one to the other, which would violate causality from the standard view. The "choice" is the ability of the photon to "feel out" all the possible paths it could take, and select an event in the future to which to tie itself to. This might be interpreted as a basis for "fate", which is fine by me, since that's the way I lean anyhow.
Obviously (as IANAP) this explanation is worded poorly and not really an accurate representation of the weird math involved. But, while information is "traveling back in time", I don't think there is a practical way to use this effect as a communications medium. Maybe you could have four entangled beams (two each for two observers)?
I've got a bad attitude and karma to burn. Go ahead. Mod me down.
In quantum mechanics, the momentum distribution of a particle is the Fourier Transform of its position distribution. When the position distribution is narrower, the momentum distribution is wider, and vice versa. This is the basic property of FT. In fact there's a simple counter-argument to the probe effect, because when you hit something with a certain impulse and you know the mass of the particle, you can predict how the hit affects its motion.
[Disclaimer: IAAP]
Escher was the first MC and Giger invented the HR department.
The object has to be at the bottom of a pool filled with some opaque liquid; a transducer is immersed, bathing the object with ultrasound. Sound waves reflect on the object, and they form an interference pattern on the surface, which is lit by coherent light, thus forming a virtual image of the object.
One caveat, though... Given the ***BIG*** difference of wavelength, the virtual image appears to be quite far, and has to be viewed with a telescope...
better type some random text in here to dodge the lameness filter -
disclaimer: this post really was not intended as a troll or a flame - but if you're going to criticise people for not understanding Heisenberg's Uncertainty Principle, maybe you should help those who don't to do so.
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
And at FAR below the price (even the alleged 'Hologram' arcade game from Sega in 1991 or so was based on the same principle):
t ml
http://www.exploratoriumstore.com/miragemaker.h
Just because you can mod me down, doesn't mean you're right. Shoes for industry!
Abouraddy,A., Saleh,B., Sergienko,A., and Teich,M. Quantum holography (PDF, 169KB, 8pages), Optics Express, 9, 498-505 (2001).
Read the damn thing (if you can :-)), then discuss.
17779 eligible voters in a district, 17779 'vote' as one. This is Russia.
Basically, a quantum particle - like an electron - exists in a somewhat undefined state. Its location and energy are not fixed, but exist more as a set of probabilities. These probabilitiy fields are calculable and are the basis for electron shell level/sublevel 3d models.
The thing that makes all this interesting is that the certainty that a particle's position and energy level can be determined are limited. The more you define one, the fuzzier the other gets. This is not an observational thing, but an intrinsic property, as has been demonstrated by cooling some Cs atoms to
What Schroedinger's cat is all about is the fact that quantum state (the probability cloud) does not collapse until observed. I suppose that means interaction, though Physicists keep calling observation. The cat is representative of some quantum particle in an indeterminate state. It wanders between quantum energy levels until you observe it. Then the quantum state collapses into one of these levels and interacts. This also has been confirmed (the weird travel in between adjacent energy levels) - Some scientists found that they were able to keep a group of atoms from changing energy levels by constantly observing them, whereas another group, which was observed less frequently, did change levels.
Reboot macht Frei.
IANAP but two of these and an entangled atomic laser = mass duplication / transportation device?
With an atomic laser it is theorized that you can create a matter hologram, whatever that is, supposedly just like the original.
Wonder if it hangs around after you turn off the reference beam? It would be a bitch if you lost the original.. poof!
It's baffling to me that no one seems to have pointed this out, but the important applications of this technology are likely to be in light microscopy, not scanning luggage. Particularly light microscopy of biological tissues. This could be a very important advance.