Re: [ccp4bb] quantum diffraction
Can't find your reference unless you are referring to this one: JOURNAL OF MODERN OPTICS, 1994, VOL .41, NO .12, 2413-2423 In case I'm wrong, could you post the direct link for download of Dale's paper ? Thanks, Jürgen - Jürgen Bosch Johns Hopkins Bloomberg School of Public Health Department of Biochemistry & Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street, W8708 Baltimore, MD 21205 Phone: +1-410-614-4742 Lab: +1-410-614-4894 Fax: +1-410-955-3655 http://web.mac.com/bosch_lab/ On Oct 16, 2010, at 11:36 AM, Bernhard Rupp wrote: >> The wave function doesn't collapse to a single outcome >> until the detector measures something > > Reference: > Tronrud D, Entanglement-phasing in Quantumcryptocrystallography, > Nature epub, doi:0101010. > > >
Re: [ccp4bb] quantum diffraction
> The wave function doesn't collapse to a single outcome > until the detector measures something Reference: Tronrud D, Entanglement-phasing in Quantumcryptocrystallography, Nature epub, doi:0101010.
Re: [ccp4bb] quantum diffraction
On 10-10-15 02:14 PM, Dale Tronrud wrote: ... The photon both diffracts and doesn't diffract as it passes through the crystal and it diffracts into all the directions that match the Bragg condition. The wave function doesn't collapse to a single outcome until the detector measures something - which in the scheme of things occurs long after the photon left the crystal. ... and On 10-10-15 02:07 PM, Bryan Lepore wrote: btw, buckyballs have measurable wave properties. i think they are trying virus particles now. That reminds me that politicians also have wave properties photons interact with electrons their diffraction leads to interference for most angles the results cancel out when they are not on a common wavelength you get Laue diffraction their is no single outcome until the detector measures something politicons interact with the electorate their diffrent fractions lead to interference on most angles the results cancel out when they are not on a common wavelength you get loud distraction there is no single outcome until the polls measure something Bart -- Bart Hazes (Associate Professor) Dept. of Medical Microbiology& Immunology University of Alberta 1-15 Medical Sciences Building Edmonton, Alberta Canada, T6G 2H7 phone: 1-780-492-0042 fax:1-780-492-7521
Re: [ccp4bb] quantum diffraction
Arndt, M.; O. Nairz, J. Voss-Andreae, C. Keller, G. van der Zouw, A. Zeilinger (14 October 1999). "Wave-particle duality of C60". Nature 401: 680-682. doi:10.1038/44348. They came up with 2.5 pm for the C60. -Original Message- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Bryan Lepore Sent: Friday, October 15, 2010 1:07 PM To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] quantum diffraction btw, buckyballs have measurable wave properties. i think they are trying virus particles now.=
Re: [ccp4bb] quantum diffraction
On 10/15/10 12:38, Bart Hazes wrote: > The photon moves through the crystal in finite time and most of the time > it keeps going without interacting with the crystal, i.e. no > diffraction. However, if diffraction occurs it is instantaneous, or at > least so fast as to consider it instantaneous. In some cases a > diffracted photon diffracts another time while passing through the > remainder of the crystal. Or in Ruppian terms, a poof-pop-poof-pop > event. If you listen carefully you may be able to hear it. > The photon both diffracts and doesn't diffract as it passes through the crystal and it diffracts into all the directions that match the Bragg condition. The wave function doesn't collapse to a single outcome until the detector measures something - which in the scheme of things occurs long after the photon left the crystal. The photon also interacts with the electrons for as long as the wave functions overlap. You have to solve the time-dependent Schrodinger equation to get the details. In all the the QM classes I've had they start by writing the time-dependent equation and then immediately erasing it - never to be mentioned again. All the rest of the term was spent with the time-independent equation and the approximation of the "instantaneous quantum jump." If you assume that nothing changes with time the only way to model changes is with discontinuities. Dale > Bart > > On 10-10-15 12:43 PM, Jacob Keller wrote: >>> >but yes, each "photon" really does interact with >>> EVERY ELECTRON IN THE CRYSTAL at once. >> >> A minor point: the interaction is not really "at once," is it? The >> photon does have to move through the crystal over a finite time. >> >> JPK >
Re: [ccp4bb] quantum diffraction
btw, buckyballs have measurable wave properties. i think they are trying virus particles now.
Re: [ccp4bb] quantum diffraction
On 10-10-15 10:37 AM, James Holton wrote: ... In fact, anyone with a Pilatus detector (and a lot of extra beam time) can verify the self-interference of photons in macromolecular crystal diffraction. Since the source-to-detector distance of a typical MX beamline is about 30 m, it takes 100 nanoseconds for a "photon" generated in the storage ring to fly down the beam pipe, do whatever it is going to do in the crystal, and then (perhaps) increment a pixel on the detector. So, as long as you keep the time between photons much greater than 100 nanoseconds you can be fairly confident that there is never more than one photon anywhere in the beamline at a given instant. ... Does the length of the beamline really matter? As long as the photons are spaced apart more than the coherence length (several 1000 A to several 10um on a synchrotron beamline according to Bernard's post) they should be considered independent events. So the photon rate can probably be 5 to 6 orders of magnitude higher while still doing "single photon diffraction" experiments. Bart -- Bart Hazes (Associate Professor) Dept. of Medical Microbiology& Immunology University of Alberta 1-15 Medical Sciences Building Edmonton, Alberta Canada, T6G 2H7 phone: 1-780-492-0042 fax:1-780-492-7521
Re: [ccp4bb] quantum diffraction
The photon moves through the crystal in finite time and most of the time it keeps going without interacting with the crystal, i.e. no diffraction. However, if diffraction occurs it is instantaneous, or at least so fast as to consider it instantaneous. In some cases a diffracted photon diffracts another time while passing through the remainder of the crystal. Or in Ruppian terms, a poof-pop-poof-pop event. If you listen carefully you may be able to hear it. Bart On 10-10-15 12:43 PM, Jacob Keller wrote: >but yes, each "photon" really does interact with EVERY ELECTRON IN THE CRYSTAL at once. A minor point: the interaction is not really "at once," is it? The photon does have to move through the crystal over a finite time. JPK -- Bart Hazes (Associate Professor) Dept. of Medical Microbiology& Immunology University of Alberta 1-15 Medical Sciences Building Edmonton, Alberta Canada, T6G 2H7 phone: 1-780-492-0042 fax:1-780-492-7521
Re: [ccp4bb] quantum diffraction
In temporary sense, the 'at once' I think really means this - poof - photon gone - pop - photon comes out. I am afraid one has to absolve oneself from the travelling photon picture once a QM transition occurs. br -Original Message- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Jacob Keller Sent: Friday, October 15, 2010 11:44 AM To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] quantum diffraction > >but yes, each "photon" really does interact with > EVERY ELECTRON IN THE CRYSTAL at once. A minor point: the interaction is not really "at once," is it? The photon does have to move through the crystal over a finite time. JPK
Re: [ccp4bb] quantum diffraction
>but yes, each "photon" really does interact with EVERY ELECTRON IN THE CRYSTAL at once. A minor point: the interaction is not really "at once," is it? The photon does have to move through the crystal over a finite time. JPK
Re: [ccp4bb] quantum diffraction
>but yes, each "photon" really does interact with EVERY ELECTRON IN THE CRYSTAL at once. Take a crystal from the cave...10m long..perhaps not 'really'... It is however helpful to think of a coherence volume of the photon in which it interacts with every atom. We had some discussions and estimates before, and starting from transition lifetime we ended up with an estimated 'single photon coherence length' of a several 1000 A to several 10um or so on synchrotron sources. These numbers at least seem reasonable and are not contradicting any practical observations. What 'really' happens depends on your definition of realityI like the photon annihilation- creation picture, but in condensed multi-particle matter that also stretches at least my imagination... Best, BR *** Jacob Pearson Keller Northwestern University Medical Scientist Training Program Dallos Laboratory F. Searle 1-240 2240 Campus Drive Evanston IL 60208 lab: 847.491.2438 cel: 773.608.9185 email: j-kell...@northwestern.edu ***
Re: [ccp4bb] quantum diffraction
>but yes, each "photon" really does interact with EVERY ELECTRON IN THE CRYSTAL at once. Take a crystal from the cave...10m long..perhaps not 'really'... It is however helpful to think of a coherence volume of the photon in which it interacts with every atom. We had some discussions and estimates before, and starting from transition lifetime we ended up with an estimated 'single photon coherence length' of a several 1000 A to several 10um or so on synchrotron sources. These numbers at least seem reasonable and are not contradicting any practical observations. What 'really' happens depends on your definition of realityI like the photon annihilation- creation picture, but in condensed multi-particle matter that also stretches at least my imagination... Best, BR
[ccp4bb] quantum diffraction
Oh dear, here we go again. I know that there are people out there who have a hard time accepting quantum mechanics, but yes, each "photon" really does interact with EVERY ELECTRON IN THE CRYSTAL at once. Young's double-slit experiment is the simplest form of diffraction, which he performed in 1801 to settle an argument about the wave vs particle nature of light. The tricky bit, however, was performing the experiment at such low flux that only one "particle" is "in flight" at any given moment (Dontai et al. 1973, done with electron diffraction). However, if you do this, you still get an interference pattern at the end of the day: http://en.wikipedia.org/wiki/File:Double-slit_experiment_results_Tanamura_2.jpg This is the observation, and Mother Nature doesn't care if we like it or not. The only way we can interpret it is to conclude that the photon must be "interfering with itself". In fact, anyone with a Pilatus detector (and a lot of extra beam time) can verify the self-interference of photons in macromolecular crystal diffraction. Since the source-to-detector distance of a typical MX beamline is about 30 m, it takes 100 nanoseconds for a "photon" generated in the storage ring to fly down the beam pipe, do whatever it is going to do in the crystal, and then (perhaps) increment a pixel on the detector. So, as long as you keep the time between photons much greater than 100 nanoseconds you can be fairly confident that there is never more than one photon anywhere in the beamline at a given instant. Now, one photon per 100 nanoseconds is 1e7 photons/s, which is a pretty weak flux for an MX beamline, but not too bad. Ideally, of course, one would want to read out images from the Pilatus that contain at most one photon hit each. You would then sum these images all together after the experiment to confirm that you do, in fact, get the same diffraction pattern that you would have gotten using higher flux. I am willing to take bets on this! Then again, this is exactly how the old multi-wire detectors worked (at much lower flux). So, I suppose this experiment has already been done? The other observation that can only be explained by quantum mechanics is the fact that electrons orbiting atomic nuclei do not emit synchrotron radiation. Amazingly, this latter conclusion was first reached by Debye in the introduction of his now famous paper on temperature factors (Debye, P. J. W. 1915, Annalen der Physik 351, 809-823). http://dx.doi.org/10.1002/andp.19153510606 Yes, this is the paper where Debye first defines what we now call the "B-factor" (although he doesn't use "B"), as well as the first occurrence of the Lorentz factor (which appears in a second note-added-in-proof). If you read it (perhaps with the help of Google translate), you can tell that the conclusion about the de-localized nature of electrons in atoms was deeply disturbing to him as well. After all, we are all scientists, and letting go of determinism is not easy. -James Holton MAD Scientist
