For the First Time Ever, Scientists Watch an Atom's Electrons Moving in Real Time

August 4, 2010 by Paul Preuss
For the first time ever, scientists watch an atom's electrons moving in real time

Enlarge

A classical diagram of a krypton atom (background) shows its 36 electrons arranged in shells. Researchers have measured oscillations of quantum states (foreground) in the outer orbitals of an ionized krypton atom, oscillations that drive electron motion. Credit: courtesy Lawrence Berkeley National Laboratory

(PhysOrg.com) -- An international team of scientists led by groups from the Max Planck Institute of Quantum Optics (MPQ) in Garching, Germany, and from the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley has used ultrashort flashes of laser light to directly observe the movement of an atom's outer electrons for the first time.

Through a process called attosecond absorption spectroscopy, researchers were able to time the oscillations between simultaneously produced quantum states of valence electrons with great precision. These oscillations drive electron motion.

"With a simple system of krypton atoms, we demonstrated, for the first time, that we can measure transient absorption dynamics with attosecond pulses," says Stephen Leone of Berkeley Lab's Chemical Sciences Division, who is also a professor of chemistry and physics at UC Berkeley. "This revealed details of a type of electronic motion - coherent superposition - that can control properties in many systems."

Leone says an example of the importance of coherent dynamics is its crucial role in photosynthesis, citing recent work by the Graham Fleming group at Berkeley. "The method developed by our team for exploring coherent dynamics has never before been available to researchers. It's truly general and can be applied to attosecond electronic dynamics problems in the physics and chemistry of liquids, solids, biological systems, everything."

The team's demonstration of attosecond absorption spectroscopy began by first ionizing krypton atoms, removing one or more outer valence electrons with pulses of near-infrared laser light that were typically measured on timescales of a few femtoseconds (a femtosecond is 10^-15 second, a quadrillionth of a second). Then, with far shorter pulses of extreme ultraviolet light on the 100-attosecond timescale (an attosecond is 10^-18 second, a quintillionth of a second), they were able to precisely measure the effects on the valence electrons.

The results of the pioneering measurements performed at MPQ by the Leone and Krausz groups and their colleagues are reported in the August 5 issue of the journal Nature.

Parsing the fine points of valence electron motion

Valence electrons control how atoms bond with other atoms to form molecules or crystal structures, and how these bonds break and reform during chemical reactions. Changes in molecular structures occur on the scale of many femtoseconds and have often been observed with femtosecond spectroscopy, in which both Leone and Krausz are pioneers.

For the first time ever, scientists watch an atom's electrons moving in real time
Enlarge

In krypton's single ionization state, quantum oscillations in the valence shell cycled in a little over six femtoseconds. Attosecond pulses probed the details (black dots), filling the gap in the outer orbital with an electron from an inner orbital, and sensing the changing degrees of coherence between the two quantum states thus formed (below). Credit: Courtesy Lawrence Berkeley National Laboratory

Zhi-Heng Loh of Leone's group at Berkeley Lab and UC Berkeley worked with Eleftherios Goulielmakis of Krausz's group to perform the experiments at MPQ. By firing a femtosecond pulse of infrared laser light through a chamber filled with krypton gas, atoms in the path of the beam were ionized by the loss of one to three valence electrons from their outermost shells.

The experimenters separately generated extreme-ultraviolet attosecond pulses (using the technique called "high harmonic generation") and sent the beam of attosecond probe pulses through the krypton gas on the same path as the near-infrared pump pulses.

By varying the time delay between the pump pulse and the probe pulse, the researchers found that subsequent states of increasing ionization were being produced at regular intervals, which turned out to be approximately equal to the time for a half cycle of the pump pulse. (The pulse is only a few cycles long; the time from crest to crest is a full cycle, and from crest to trough is a half cycle.)

"The femtosecond pulse produces a strong electromagnetic field, and ionization takes place with every half cycle of the pulse," Leone says. "Therefore little bursts of ions are coming out every half cycle."

Although expected from theory, these isolated bursts were not resolved in the experiment. The attosecond pulses, however, could precisely measure the production of the ionization, because ionization - the removal of one or more electrons - leaves gaps or "holes," unfilled orbitals that the ultrashort pulses can probe.

For the first time ever, scientists watch an atom's electrons moving in real time
Enlarge

Femtosecond-scale pulses were fired to ionize krypton atoms (wide beam). Separately created attosecond-scale pulses (narrow beam) were absorbed by the krypton atoms. Spectroscopy mapped the precise timing of the oscillation between quantum states thus created. Credit: Courtesy Lawrence Berkeley National Laboratory

The attosecond pulses do so by exciting electrons from lower energy orbitals to fill the gap in krypton's outermost orbital - a direct result of the absorption of the transient attosecond pulses by the atoms. After the "long" femtosecond pump pulse liberates an electron from the outermost orbital (designated 4p), the short probe pulse boosts an electron from an inner orbital (designated 3d), leaving behind a hole in that orbital while sensing the dynamics of the outermost orbital.

In singly charged krypton ions, two electronic states are formed. A wave-packet of electronic motion is observed between these two states, indicating that the ionization process forms the two states in what's known as quantum coherence.

Says Leone, "There is a continual 'orbital flopping' between the two states, which interfere with each other. A high degree of interference is called coherence." Thus when the attosecond probe pulse clocks the outer valence orbitals, it is really clocking the high degree of coherence in the orbital motion caused by ionization.

Indispensable attosecond pulses

"When the bursts of ions are made quickly enough, with just a few cycles of the ionization pulse, we observe a high degree of coherence," Leone says. "Theoretically, however, with longer ionization pulses the production of the ions gets out of phase with the period of the electron wave-packet motion, as our work showed."

So after just a few cycles of the pump pulse, the coherence is washed out. Thus, says Leone, "Without very short, attosecond-scale probe pulses, we could not have measured the degree of coherence that resulted from ionization."

The physical demonstration of attosecond transient absorption by the combined efforts of the Leone and Krausz groups and their colleagues will, in Leone's words, "allow us to unravel processes within and among , molecules, and crystals on the electronic timescale" - processes that previously could only be hinted at with studies on the comparatively languorous femtosecond timescale.

More information: "Real-time observation of valence electron motion," by Eleftherios Goulielmakis, Zhi-Heng Loh, Adrian Wirth, Robin Santra, Nina Rohringer, Vladislav Yakovlev, Sergey Zherebtsov, Thomas Pfeifer, Abdallah Azzeer, Matthias Kling, Stephen Leone, and Ferenc Krausz, appears in the 5 August 2010 issue of the journal Nature.

Provided by Lawrence Berkeley National Laboratory (news : web)

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Warrensn
Aug 04, 2010

Rank: 1.6 / 5 (5)
That's a beautiful image. Attosecond pulses? If we can measure attosecond pulses, wouldn't that make the atomic clock obsolete?
Doug_Huffman
Aug 04, 2010

Rank: 1.5 / 5 (6)
Human visual 'bandwidth' 8960 kilobits per second pales, is blind to attoseconds. http://www.newsci...of-sight
Objectivist
Aug 04, 2010

Rank: 5 / 5 (1)
Sherlock: The same logic would apply for any interval of time. The unit is however defined by cesium 133 decay, which is of course merely another interval.

Wattson: The "recording" is of course slowed down for human observation. We can observe the electron several times during the same period. Meaning we can follow it as it oscillates live and inconsistent, instead of merely calculating an average. Hence the illustration.
Going
Aug 04, 2010

Rank: 5 / 5 (2)
"One attosecond is to one second what one second is to twice the age of the universe." - Wikipedia
Question
Aug 04, 2010

Rank: not rated yet
Quote from article: "The femtosecond pulse produces a strong electromagnetic field, and ionization takes place with every half cycle of the pulse," Leone says. "Therefore little bursts of ions are coming out every half cycle."

What I don't understand is how half of a cycle can cause ionization? Is 1/2 a photon causing this ionization?
abzu
Aug 04, 2010

Rank: 5 / 5 (3)
What does this mean for Uncertainty?
franco_bonafe
Aug 04, 2010

Rank: 5 / 5 (2)
What does this mean for Uncertainty?

Same question. I presume Heisenberg's Uncertainty Principle is still valid 'cause you need to ionize the atom in order to "observe" the electrons. The principle applies if electrons are observed in its fundamental state, and not in transitions between states?
Ethelred
Aug 05, 2010

Rank: 3.3 / 5 (3)
Question:
What I don't understand is how half of a cycle can cause ionization? Is 1/2 a photon causing this ionization?
Half a cycle is the extreme opposite of a full cycle. So every half cycle should get the same result as a full cycle. At least I think that is what is going on.

abzu :
What does this mean for Uncertainty?
That was what I was thinking when I first saw the headline link. However they are observing the electrons so that should make them behave as if they were particles and not as waves. That is they are testing for the position of the electrons and not the momentum of the electrons. As pointed out in the article the results were as expected by theory.

Ethelred
unit
Aug 05, 2010

Rank: 2 / 5 (1)
How does this affect the Heisenburg Uncertainty principle? Seems like if they can see it moving in real time they would be able to simultaneously know the electrons' position and momentum. Can anyone clarify?
denijane
Aug 05, 2010

Rank: not rated yet
Yeah, isn't that measurement supposed to collapse the wave function of the electron?
From what I read, I don't think that the title is very correct. They didn't measure motion but ionization rates and coherences degrees. Which of course imply motion, but then, with electrons what doesn't...
Ethelred
Aug 06, 2010

Rank: 3.7 / 5 (3)
? Seems like if they can see it moving in real time they would be able to simultaneously know the electrons' position and momentum


It wasn't in real time. It was in pulses. Each pulse would collapse any waveform. They did not see individual electrons. They saw SOME electrons in SOME atoms, SOME of the time.

Rarely if ever did they see the same electron two pulses in a row.

Ethelred
Objectivist
Aug 06, 2010

Rank: 5 / 5 (1)
It wasn't in real time. It was in pulses. Each pulse would collapse any waveform. They did not see individual electrons. They saw SOME electrons in SOME atoms, SOME of the time.

Real time is pulses, as governed by quantum mechanics.
How does this affect the Heisenburg Uncertainty principle? Seems like if they can see it moving in real time they would be able to simultaneously know the electrons' position and momentum. Can anyone clarify?

Once you launch a photon at an electron you change its state. Thus what you see is only a snapshot of what it was before you changed it. You can never know what the product of your interaction became until you probe it again -- at which point you face the same paradox. Heisenberg's uncertainty principle is so simple that it describes the paradox of any type of interaction/observation in all possible universes where energy cannot be lost or created, but rather transformed -- such as ours (if the former is even conceptually possible.)
shuwesh
Aug 06, 2010

Rank: 1.5 / 5 (2)
Heisenberg Uncertainty is far from certain. Hans Dehmelt of Germany won the Nobel Prize in Physics for a series of experiments which held an electron pinned to one spot, while simultaneous measurements of the momentum and position of the electron were performed, with complete confidence in both measurements. Dehmelt was able to confine and measure the same electron for spans of time as long as 3 months.

Secondly, Heisenberg Uncertainty does not apply to monochromatic light, in any regard. See: http://blog.hassl...n_a.html
Ethelred
Aug 06, 2010

Rank: 3 / 5 (2)
Real time is pulses, as governed by quantum mechanics.
That is not what was going on in the experiment, and while I might agree with you if you spell that out a bit more it isn't actually presently part of QM. Pulses meant a discontinuous series of instantaneous views. Which results in a collection of fixed points and thus no momentum.

Maybe if they can manage it with a Plank interval. How it could be done is another thing as light just won't do that.

Heisenberg's uncertainty principle is so simple that it describes the paradox


What paradox? It does describe the interactions but not the paradox of the interactions since there is no paradox.

Ethelred
Ethelred
Aug 07, 2010

Rank: 3.7 / 5 (3)
Hans Dehmelt of Germany won the Nobel Prize in Physics for a series of experiments which held an electron pinned to one spot, while simultaneous measurements of the momentum and position of the electron were performed, with complete confidence in both measurements.
Not quite. He got the Nobel for an ION trap. He did also trap electrons but it was the work with ions that got the Nobel.

http://nobelprize...es/1989/

Ions, being heavier than electrons can have a more precise measurement of their position and momentum. More precise being the key as an electron can have both its momentum and position measured at the same time. However the more precise the measurement of one property is the less precise the other property can be measured. For instance if you trap an electron with, oh say lasers, and cut its velocity to millimeters per second then its position becomes vague. Every test has had this result. Or worse if the test is badly done.

Ethelred
MagneticCurrents
Aug 07, 2010

Rank: 1 / 5 (2)
Important message for you scientists of the world: Regarding all this confusion & complications of only three things North pole individual magnets / South pole individual magnets & the Neutral particles of Matter !
In short > "Quantum Coherence" = "MAGNETIC CURRENTS"
zevkirsh
Aug 07, 2010

Rank: not rated yet
ive been observing atoms and electrons in real time. my whole life, all day, everyday. just cause i can't see them at their smallest resolution doesn't mean i haven't been. let me get an amen for science.
shuwesh
Aug 08, 2010

Rank: 3.5 / 5 (2)
Ethelred stated: "However the more precise the measurement of one property is the less precise the other property can be measured."

This statement wants to dogmatically deny the entire of the Dehmelt Nobel Prize, which demonstrated simultaneous measurement of the momentum and the position, of both electrons and ions, contrary to the "uncertainty principle" which is merely an abstract mathematical theory, not a physical fact. Uncertainty is not based on empirical observation, which observations denies "uncertainty" per Dehmelt, and per the proof regarding monochromatic photons in the reference cited.

Clinging to the "known" does not a good scientist make. Exploring beyond the "known" is what makes a good scientist.
Ethelred
Aug 09, 2010

Rank: 3.7 / 5 (3)
This statement wants to dogmatically deny the entire of the Dehmelt Nobel Prize
Did you read what I wrote OR the Nobel Prize pages I linked to? I am merely saying the same thing Dehmelt would tell you.

Nothing he did was contrary to the uncertainty principle. It is that simple and is in no dogmatic. Its a simple fact. YOU are the making the claim NOT Dehmelt. At no time did I deny his work. Just your FALSE claims about it.
contrary to the "uncertainty principle" which is merely an abstract mathematical theory, not a physical fact.
Which fits every experiment. Including Dehmelt's.
Clinging to the "known" does not a good scientist make
Clinging to false interpretation of someone else's work who DOES NOT agree with your claims is a sign of a crank.

YOU made the claim now post link or something to support your claim. I posted the stuff you misunderstood and that supported me and the Uncertainty Principle. It is funny how Demelt DID NOT make the claim you did.

Ethelred
shuwesh
Aug 13, 2010

Rank: 3.5 / 5 (2)
I read those pages long before you did. And clearly you did not read the link I presented, which discusses the fact that the Uncertainty Principle cannot be applied to monochromatic photons. For example, if I am observing coherent monochromatic light, at any point in time along the line A-B, I can predict each and every one of these factors: Wavelength, Frequency, Polarization Angle, Phase, Momentum, and Position of the photons, simultaneously, with complete certainty.

E.G., the only limitation to accuracy of position is the time of emission accuracy which is related to the accuracy of the timer. NASA has developed a timer system accurate to 10 femtoseconds, with projections of improvements into the .001 femtosecond regime. Emission time is then not an issue over a pre-measured course and thus location of the photon is known to within the accuracy limits of the timer.

We can know momentum with absolute certainty because the momentum of a photon is directly related to its frequency.
Ethelred
Aug 14, 2010

Rank: 3 / 5 (2)
clearly you did not read the link I presented, which discusses the fact that the Uncertainty Principle cannot be applied to monochromatic photons
It applies to all particles. And I just double checked and I DID look at the blog you linked to. Its a Crank site written by a health worker. Why should I take his word on anything? Then again you didn't link to anything about monochromatic light in anycase. I am not not going to hunt all over a cranks site for more crap than was on the page you linked to.
I can predict each and every one of these factors: Wavelength
Yes, in part.
Frequency
That is inherent in the frequency.
Polarization Angle, Phase
Yes for angle, no for phase.
Momentum
Yes, and oops:
and Position of the photons, simultaneously, with complete certainty
NO. You can't know the position.

Explanation follows
Ethelred
Aug 14, 2010

Rank: 3.7 / 5 (3)
The photons in a coherent beam are entangled and therefor they overlap on top of not being able to know both the momentum and position at the same time for ANY specific photon much less a larger number of entangled photons.

Just claiming that you can do something doesn't mean you can and in this instance you don't even understand that 'coherent' entails entanglement.
NASA has developed a timer system accurate to 10 femtoseconds
Doesn't matter for TWO reasons. ONE the photons are entangled or they are not coherent. TWO 10 femtoseconds is precision but is in no way complete certainty. Which is what you claimed. Same for attoseconds only you get more precision but you still get entanglement and a lack of simultaneous MEASUREMENT. You CAN predict, but not measure, to attosecond accuracy. Which simply isn't complete certainty.

Yes there is more.
Ethelred
Aug 14, 2010

Rank: 3 / 5 (2)
with projections of improvements into the .001 femtosecond regime.
There was and article about attosecond pulses in the last week. Still isn't exact. To get an exact measurement you would have to actually affect the photon with the instruments used to measure. Thus either testing for position or momentum both at the same time one will be limited inversely by the accuracy of the other.
We can know momentum with absolute certainty because the momentum of a photon is directly related to its frequency.
Which still doesn't get you absolute certainty of the position. Not only of the packet of photons but FOR ANY of the photons because they are coherent and thus entangled which means that ALL the photons are smeared over the entire volume of the packet.

And next time you post a link you might try to actually give a clue as to where the heck the information is if the link is so vastly less specific than your thought experiment.

Ethelred
shuwesh
Aug 14, 2010

Rank: 3.5 / 5 (2)
How much would you like to wager as to whether or not I can know the phase of the photon at any point along a pre-measured course? Coherent light makes this measurement even more precise. And by the way, these several simultaneous measurements do not require us to influence the photon in any regard. Heisenberg made a mistake by treating electrons and photons in exactly the same way (identical), when they are not identical in any way. Ions and electrons and photons are all different kinds of particles and have different physical properties and behaviors. As to the certainty of these various simultaneous measurements, for all practical purposes they are exact. The uncertainty principle clearly has limited domains of applicability, especially with regard to monochromatic photons.

Labeling anything that disagrees with "standard" concepts as "crank" or "crackpot" makes you appear the same way as a dogmatic religious fanatic. Science is not a religion. Is is a search for observable facts.
Ethelred
Aug 15, 2010

Rank: 3 / 5 (2)
How much would you like to wager as to whether or not I can know the phase of the photon at any point along a pre-measured course
Nothing. Bets are for people trying to run a bluff.

Since the photons are entangled you cannot measure a single photon. Thus you cannot know the phase.
Coherent light makes this measurement even more precise.
Less. Due to entanglement.
And by the way, these several simultaneous measurements do not require us to influence the photon in any regard.
Then you didn't measure a single photon or even a coherent packet.
Heisenberg made a mistake by treating electrons and photons in exactly the same way (identical)
No. They have different masses and thus are different. Not counting spin.
Ions and electrons and photons are all different kinds of particles and have different physical properties and behaviors
And with different masses which is what Heisenberg was dealing with.
Ethelred
Aug 15, 2010

Rank: 3.7 / 5 (3)
As to the certainty of these various simultaneous measurements, for all practical purposes they are exact.
No. They are entangled and thus smeared out. Nor is 'for all pracitcal purposes' relevant to uncertainty measurements. Precision is the key. This isn't horse shoes or hand grenades.
The uncertainty principle clearly has limited domains of applicability, especially with regard to monochromatic photons.


A claim you have failed to show any support for and I showed the problems with your claims. However if you can show that someone has actually has done the experiment and gotten the claimed results then I will be willing to change my mind. So far all I have your unsupported claims. Even your link had nothing to support your claims. Nor did Dehmel ever say anything that supports you. I asked for evidence and you have only given me YOU. You don't seem to have done the experiments either. Just made the claims.
Ethelred
Aug 15, 2010

Rank: 3.7 / 5 (3)
Labeling anything that disagrees with "standard" concepts as "crank" or "crackpot" makes you appear the same way as a dogmatic religious fanatic.
Utter rubbish. I am NOT going on faith. I am going on decades of evidence that supports the Uncertainty Priciple. You are going on a Gedankenexperiment where you don't understand what coherent entails nor have you made any effort to support your claims. When I pointed out that Dehmel never said anything that supports what you claim you simple ignored the issue. Which is quite popular with people that are blowing smoke.
Science is not a religion. Is is a search for observable facts.
Hey we agree on something. Now where are the observations that support you and show that coherent light is not entangled. Where is something that shows Dehmel supports your version of what he REALLY did?

Ethelred
shuwesh
Aug 15, 2010

Rank: 1 / 5 (1)
Dear Ethelred, You are confusing randomities inherent in white light with the behaviors and properties of LASER systems.(A common error, which is even made by university professors.)The above well-known expressions of the physical behaviors and properties of the photons in LASER systems are not at all "thought experiments", but are in common use every day by DoD and NASA. There is no "entanglement" in the coherent monochromatic photons which are called LASER beams. LASER ranging systems which are commonly used in military and commercial applications all rely on the certainties of the behaviors of photons in coherent monochromatic light, to do their jobs. If LASER light was at all randomized internal to the beam, a great many optical techniques such as "adaptive optics" and "phase conjugate optics" would not be available to us, nor in common use. Do either of these two terms mean anything to you?

Heisenberg uncertainty does not apply to LASER optics. That is physical fact, not theory.
shuwesh
Aug 15, 2010

Rank: 1 / 5 (1)
"Polarimetry of Scattered Light Using Coherent Laser Radar" Tenth Biennial Coherent Laser Radar Technology and Applications Conference, Page: 207-210
Abstract: Measurement of the polarisation properties of light (polarimetry) is a powerful diagnostic tool with uses in many applications including ellipsometry. The horizontally and vertically polarized components of light scattered from depolarising surfaces were independently measured by a two-channel coherent laser radar. Because of the phase-sensitive nature of heterodyne detection, the relative phase of these components can be measured, and this gives all the information required to construct the polarization ellipse at any instant. The phenomenon of laser speckle ensures that the intensity and polarization state fluctuate as the beam scans across the surface of the target. The method described allows the time development of the polarization state to be followed in real time.
shuwesh
Aug 15, 2010

Rank: 1 / 5 (1)
"Laser Beams And Images Adaptive Correction, Including Laser Guide Star Schemes For Formation And The Tip-Tilt Problem" Academy of Sciences (Russia) (Tomsk, Russia)Report #:AD-A370706, EOARD-SPC-98-4041
Institute of Atmospheric Optics RAS
"...optical wave propagation in the atmosphere, calculating the parameters of optical waves propagating in both inhomogeneous layers and random-inhomogeneous stratified media under the conditions of thermal blooming."
frajo
Aug 15, 2010

Rank: 5 / 5 (1)
I've made a mistake by rating some of shuwesh's comments with "2" before looking at his Hasslberger link which opens a site with the highest density of nonsense I've ever met.
The title "Continuous Creation, Einstein and the 'Expanding' Big-Bang Universe" is followed by another text titled "Toward an Empirical Reality in Consciousness Studies". Excerpt:
recent publications supporting a hyper-dimensional essence of Brain. These cutting-edge studies extend the Rubner-Kleiber scaling computation laws, thus reaching the inescapable conclusion that a 5-dimensional function is present in neural network connectivity of Brain, resulting vastly wider Information-coding abilities with respect to the Brain, far beyond mere quantum efficiency.
And:
We need to return to reality ... even at the expense of tearing down a holy of holies like Einstein's Relativity.
And:
Hydrogen From Space - The Aether 'Comes Alive'
And a lot more of the same quality ...
frajo
Aug 15, 2010

Rank: not rated yet
The uncertainty principle clearly has limited domains of applicability, especially with regard to monochromatic photons.
What is a "monochromatic photon"? Is there a polychromatic photon?
frajo
Aug 15, 2010

Rank: 5 / 5 (1)
For example, if I am observing coherent monochromatic light, at any point in time along the line A-B, I can predict each and every one of these factors: Wavelength, Frequency, Polarization Angle, Phase, Momentum, and Position of the photons, simultaneously, with complete certainty.
Yes, you can predict whatever you want.
But no, you cannot measure the exact position and the exact momentum of a single photon simultaneously.
shuwesh
Aug 15, 2010

Rank: not rated yet
You are using common debunking methods, rather than rational arguments involving scientific facts and observations. I seems clear to me that you are not qualified to address the topic of LASERs, nor the topic of coherent monochromatic light. Better bring in an expert to help you on these topics you are not competent in, else your public image will suffer. I only care about the truth and the facts. I am not compelled to agree with popular opinions just because they are "politically correct", and I am even less compelled by emotion-laden arguments that are in complete opposition to the facts. I made the statement that the location of the photon, and its momentum can be known with absolute certainty at any point along a pre-measured course. This is not a "thought experiment". This is common-place everyday-use technology. By the way, I invented the first CW laser ranging system when I worked for NASA at Goddard Optical Research Facility, at Goddard Space Flight Center.
shuwesh
Aug 15, 2010

Rank: 1 / 5 (1)
Dear frajo, If it is a fact that the speed of light is constant at every location and at every time, then we know where the photon is located EXACTLY along a line A to B, at any given instant. Given that we know the frequency of the monochromatic photon, we know at the same instant, its EXACT momentum, by the equation that won Einstein the Nobel Prize.

Since you asked, the prefix "mono" means "one" or "single". The word "chromatic" is an optical physics term relating to the color or colors of light. Thus, the term "monochromatic" simply means, only one color, which then means only one frequency of E/M propagation. When that light is also "coherent" (all photons perfectly in-phase)it takes on many properties that normal white light does not have, such as predictability, which predictability is used in countless laser optics systems throughout the world, to accomplish amazingly accurate measurements of diverse physical objects and events. I gave some examples earlier.
shuwesh
Aug 16, 2010

Rank: 1 / 5 (1)
In fact, the article above, which should be the actual topic of discussion, is another case in point regarding the accuracy of the many different kinds of laser measurement systems which rely on the fact that the uncertainty principle never applies to laser light.

frajo and ethelred (probably the same person) should take up the argument with the international team of scientists led by groups from the Max Planck Institute of Quantum Optics (MPQ) in Garching, Germany, and from the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley.

I'm sure they won't have the courage to argue with all those people, telling them that their experimental results are IMPOSSIBLE according to the theory called "heisenberg uncertainty".

The empirical facts always win out over theories, no matter how mathematically attractive or believible those theories might be.
Ethelred
Aug 16, 2010

Rank: 5 / 5 (2)
You are confusing randomities inherent in white light with the behaviors and properties of LASER
Not in the least. I am talking about what makes light coherent. If the light is coherent then it is entangled. Another way to look at it is the light waves overlap to point where they are indistinguishable thus making it impossible to pick any one.
There is no "entanglement" in the coherent monochromatic photons which are called LASER beams.
Yes there is. Otherwise the photons would not be coherent.
certainties of the behaviors of photons
Certainty of position means uncertainty of momentum. And don't bother telling me that is given by the frequency because it isn't. Momentum includes direction and light scatters when it makes the contact needed for detection and ranging. Also you are mistaking entanglement for randomness.

Yes there is more. I pity little minds that mistake brevity for wit
Ethelred
Aug 16, 2010

Rank: 5 / 5 (2)
If LASER light was at all randomized internal to the beam,
A claim I never made so you arguing about something that isn't there. Entangled in no way implies random.
Do either of these two terms mean anything to you?
Yes. They aren't relevant to your claim because the depend on the entangled nature of coherent light.

You don't seem to get this at all. There are NO INDIVIDUAL photons in a coherent beam. They are all smeared together thus you can't measure one photon. You are measuring a BEAM.[Heisenberg uncertainty does not apply to LASER optics. That is physical fact, not theory. This is a misunderstanding on your part not fact. BEAMS are not PHOTONS. Does THAT get through?

More clarifying thoughts to follow
Ethelred
Aug 16, 2010

Rank: 5 / 5 (2)
That article doesn't support YOUR claim. It is still measuring a beam and not photons. However it is nice that you understand the CONCEPT of evidence even if you failed to produce it. The reason you failed is that you don't get the difference between individual photons, which is what were talking about when we are dealing with Heisenberg, and a beam.

Again. A coherent monochromatic beam IS NOT a single photon. It is a collection of photons that are smeared out via entanglement. Thus while you can measure the beam you can't measure the photons that make up the beam because they don't really exist as individual photons under those conditions. And no that is not the same as randomness.

And I might add that I got some of these ways of thinking from Dr. Prins who is fighting against the physics establishment. I am not sure that I fully agree with him but some of the concepts are very useful to me in thinking about uncertainty and entanglement.

Ethelred
Ethelred
Aug 16, 2010

Rank: 5 / 5 (2)
I invented the first CW laser ranging system when I worked for NASA at Goddard Optical Research Facility, at Goddard Space Flight Center
Nice but it still isn't measuring photons. It is measuring coherent beams.

But that post was mostly garbage based unfounded speculation about what others understand. And what you actually were doing when you used laser range finding.
If it is a fact that the speed of light is constant at every location and at every time
Close. Add in a vacuum and avoid some cosmological speculation about VERY early in the history of the Universe and you have it.
Given that we know the frequency of the monochromatic photon, we know at the same instant, its EXACT momentum, by the equation that won Einstein the Nobel Prize
But we haven't measured even one photon and thus are still not dealing with Heisenberg's Uncertainty Principle. In other words you made claims that had nothing to with what you thought you were claiming.

Dennis Moore
Ethelred
Aug 16, 2010

Rank: 5 / 5 (2)
Since you asked, the prefix "mono" means "one" or "single".
Not sure why Frajo had a problem with that. English is his second language but I don't think that was what the problem was. Ah just figured it out several paragraphs later. YOU keep talking about beams but the discussion is about individual photons. Monochromatic photon is part of the Department of Redundency Department. ALL photons have a single color at any one point in their path.
When that light is also "coherent" (all photons perfectly in-phase)it takes on many properties that normal white light does not have, such as predictability
Actually white light is also predictable just to a lesser degree. Predictability however is NOT measurement.

I had a feeling what at least part of you misunderstanding was when you said:
How much would you like to wager as to whether or not I can know the phase of the photon at any point along a pre-measured course?
Extra More
Ethelred
Aug 16, 2010

Rank: 5 / 5 (2)
Which is not supporting what you claimed regarding Heisenberg and photons as that is NOT measurement of photons. You made other similar claims throughout your writing and never noticed that what you were claiming had nothing to do with MEASUREMENT of single photons which is what Heisenberg dealt with. Electrons really but the principle covers ALL particles.
In fact, the article above, which should be the actual topic of discussion,
Only we were talking about the Uncertainty Principle and you claimed to have evidence against it. Which you don't.
which rely on the fact that the uncertainty principle never applies to laser light.
Because it isn't made up of individual photons. And in any case the objects in the article that brought up the Uncertainty Principle weren't photons. It was electrons that the BEAM was being used to measure.

Those electrons had their positions measured but not their momenta. You can't get both at once with high precision. And they didn't.

Some More
Ethelred
Aug 16, 2010

Rank: 5 / 5 (2)
frajo and ethelred (probably the same person)
Another thing you are confused on. He is a European and I live near Disneyland.
should take up the argument with the international team of scientists led by groups from the Max Planck Institute of Quantum Optics (MPQ)
Why? They aren't the ones making the claim, you made it. Nothing you have posted has supported your claim:
Heisenberg Uncertainty is far from certain. Hans Dehmelt of Germany won the Nobel Prize in Physics for a series of experiments which held an electron pinned to one spot, while simultaneous measurements of the momentum and position of the electron were performed, with complete confidence in both measurements.
Remember that was what you were talking about. NOT beams. And remember that you have been unable to find a single reference of Dehmelt claiming he did what you claim he did. Or anyone else for that matter.

More later or was that litter
Ethelred
Aug 16, 2010

Rank: 5 / 5 (2)
What you have been doing is moving away from your initial claim regarding individual electrons and towards beams of photons which are not the same thing.
I'm sure they won't have the courage to argue with all those people, telling them that their experimental results are IMPOSSIBLE according to the theory called "heisenberg uncertainty".
At no time have any of those people EVER claimed what you claimed. So it is YOU that might want to argue with them. After all I am in agreement with them on most things. And I am willing to argue with them if they should make unsupported claims like you did.

However perhaps I missed something. Perhaps all the science magazines missed it too. Perhaps every paper on the planet missed it. Perhaps YOU could link to it. You know, an experiment where someone, anyone measured an electon's position and momentum simultaneously to a precision higher than the Uncertainty Principle allows.

Just a touch more
Ethelred
Aug 16, 2010

Rank: 5 / 5 (2)
Finished at last, Finished at last, Thank Einstein almighty finished at last.
The empirical facts always win out over theories, no matter how mathematically attractive or believible those theories might be.
I totally agree and await with baited breath a single reliable source to support your initial claim. I asked many times and you have yet to produce one. You and I even agreed on a person that should have made the claim since YOU said Dehmel did so. Yet you didn't produce such a claim by him. Just by you. And a bunch about predicting beams and evading actual measurement which is what you where claiming to be able to do.

Ethelred
frajo
Aug 16, 2010

Rank: 5 / 5 (1)
Thanks to Ethelred, most of the needed work is done. Just some minor supplements:
Since you asked, the prefix "mono" means "one" or "single". The word "chromatic" is an optical physics term relating to the color or colors of light. Thus, the term "monochromatic" simply means, only one color, which then means only one frequency of E/M propagation.
I didn't ask for the meaning of Greek words. Ta ellinika ksero arketa kala. My question was a hint that "monochromatic photon" is as meaningless as "polychromatic photon". Ethelred already pointed that out.
English is his second language
Not really. The second language was Latin - more lessons of that than in my native language.

One more point. I may be wrong (and will be grateful when corrected), but I don't think that coherence is the same as entanglement. Coherent light is simply a beam of light of in-step waves of identical frequency, phase, and polarization. No quantum considerations needed here.
shuwesh
Aug 18, 2010

Rank: 1 / 5 (1)
You all are demonstrating your lack of understanding of the principles of quantum mechanics. Ethelred, for example doesn't understand what is quantum entanglement at all, much less how non-locality might be applied in these kinds of measurement situations. He needs to at least review the material on Wikipedia on the topic (which is by no means complete). http://en.wikiped...nglement

Secondly, a beam of laser light is made of photons. Arguments which are trying to distinguish photons from considerations such as ray-tracing demonstrate a lack of understanding of foundational principles of optical physics and quantum physics.

Arguments that the photons have not been measured in these circumstances are also based purely in ignorance of laser optics.

Why don't you take your arguments up with the experimenters referenced in the article, as I suggested earlier? They will probably have more patience with your ignorance than I do.
Ethelred
Aug 18, 2010

Rank: 5 / 5 (2)
Ethelred, for example doesn't understand what is quantum entanglement at all
Nonsense, I may be overstating the case as I am using a way of thinking on this that I have doubts on myself. HOWEVER I also backed it up by pointing out that even by standard thinking the waveforms will overlap in a coherent beam so there is no chance of testing individual photons.
Secondly, a beam of laser light is made of photons.
Overlapping photons. And I am fully aware of what a beam of light is made of. I am also aware the beams are not what we were talking about when you claimed that people had shown Heisenberg wrong.

So quit evading and show something that backed you. You claimed that Dehmel did it. WHERE did he say he did it?

I have asked that question MANY times and you have ignored EVERY time.

More to come
Ethelred
Aug 18, 2010

Rank: 5 / 5 (2)
Arguments that the photons have not been measured in these circumstances are also based purely in ignorance of laser optics
Show where individual photons have been measured in a coherent beam for both position and momentum simultaneously of the same photon.
Why don't you take your arguments up with the experimenters referenced in the article, as I suggested earlier?
Since I never disagreed with them I don't need to. I pointed that out before. NONE of that agreed with you on your original claim. Changing what you are discussing is mere evasion.
They will probably have more patience with your ignorance than I do
I am patiently waiting for the evidence I asked for. I AM willing to change to my mind given EVIDENCE for A PHOTON being MEASURED for momentum and position simultaneously as that is what the discussion is about.

Not beams of photons being predicted or even measured. But a single photon or entangled pair of photons being MEASURED.

More about photons not beams
Ethelred
Aug 18, 2010

Rank: 5 / 5 (2)
Calling me ignorant does not make it so. Calling me ignorant does not answer ANY of the questions I asked and you evaded.

I notice when people evade I and I point it out. I also notice when it done multiple times as you have been doing.

Answer the bloody questions and quit insulting people instead.

Ethelred
Rank 4.9 /5 (62 votes)
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