What is Quantum eraser: Definition and 112 Discussions

In quantum mechanics, the quantum eraser experiment is an interferometer experiment that demonstrates several fundamental aspects of quantum mechanics, including quantum entanglement and complementarity.
The quantum eraser experiment is a variation of Thomas Young's classic double-slit experiment. It establishes that when action is taken to determine which of 2 slits a photon has passed through, the photon cannot interfere with itself. When a stream of photons is marked in this way, then the interference fringes characteristic of the Young experiment will not be seen. The experiment also creates situations in which a photon that has been "marked" to reveal through which slit it has passed can later be "unmarked." A photon that has been "marked" cannot interfere with itself and will not produce fringe patterns, but a photon that has been "marked" and then "unmarked" will interfere with itself and produce the fringes characteristic of Young's experiment.

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  1. Megatherion

    Delayed Choice Quantum Eraser & The Observer (2000)

    Hello, I signed up cause I was going through the Quantum Eraser threads, but couldn't find an answer to my question. It's about this version from 1999/2000 of the elaboration on the classic double slit experiment: Results seem quite straight forward. Wherever we have "path information" the...
  2. B

    Explain delayed choice quantum eraser without consciousness

    I'm trying to understand the delayed choice quantum eraser experiment without consciousness. As I understand it, photons will either interfere or not depending on whether or not "which-path" information is randomly hidden and rendered unkowable to the experimenter. That is, rather the by any...
  3. B

    How would MWI explain delayed choice quantum eraser?

    How would MWI explain the delayed choice quantum eraser? http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser#The_experiment_of_Kim_et_al._.282000.29 I don't see how this can be explained with MWI. If the idler photon hits detector 1 or 2, an interference pattern can be seen on the...
  4. P

    Delayed Choice Quantum Eraser

    I found other threads with the same title on this forum but my question is somehow differ. I think this was the most simple DCQE with double slits: http://arxiv.org/pdf/quant-ph/0106078v1.pdf For a short summary: the experimental setup uses an entangled pair of photons (p and s). The s-photons...
  5. J

    Quantum eraser thought experiment?

    http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser From the DCQE experiment above , assuming we could , 1. Send the idler photons on a long round trip that too a year or so before going through the double slit which is in the same lab as the detector D0. 2. Take...
  6. F

    Homemade Quantum Eraser Experiment revisited with photos and full text

    This experiment is based on a Scientific American article from April 14, 2007 ( http://www.arturekert.org/sandvox/quantum-eraser.pdf ) or ( http://www.angelfire.com/folk/thegrieves/transfer/200705.pdf in renderable text). The article demonstrates how to set up an experiment that illustrates...
  7. F

    Misc. DIY Quantum Eraser Experiment with photos and full text

  8. F

    Quantum Eraser experiment reproduced at home

    I'm just posting the bare bones of this experiment to begin with, as it was quite the task just to attach all the photos in the proper order. But this is about quantum weirdness, and how it can be demonstrated at home with polarized film, a straight piece of thin wire, and a red laser pointer...
  9. A

    What's up with the absorptive quantum eraser?

    What's up with the "absorptive" quantum eraser? In the famed "quantum eraser" of physics, there is two distinct types, one type which uses an absorptive apparatus for the method of "unmarking the path" and one which does not. For the absorptive type of quantum eraser we have a clear fallacy in...
  10. J

    Misc. DIY Quantum Eraser: Exploring the Interference of Orthogonal Light Waves

    Click here for the publication. Having performed this experiment, I have gotten clean results. Essentially, a double slit is made by putting an electron beam in the way of a wire with orthogonal polarizers on either side. This destroys the expected interference pattern since the polarized...
  11. M

    Double-slit quantum eraser: measured patterns on screen

    Consider a double-slit quantum eraser experiment such as the one by Walborn et al (http://arxiv.org/abs/quant-ph/0106078). The overall pattern formed by the signal photons on the screen behind the double slits is the same regardless of whether which-path information is available or destroyed...
  12. G

    Quantum eraser and the experimenter's retina?

    Quantum eraser and the experimenter's retina!? I just ran across the following quote from Brian Greene's "The Fabric Of The Universe": Does this erasure of some of the which-path information– even though we have done nothing directly to the signal photons– mean that the interference effects...
  13. G

    Delayed Choice Quantum Eraser communication

    Hi all, Okay, I'm writing this post keeping in mind that FTL communication (or even backward in time communication) are impossible. However, I fail to understand why this would be impossible using the delayed choice quantum eraser, so my question is: where is the error in my logic here...
  14. M

    Quantum Eraser Interference Patterns

    I'm not clear as to how the overall interference pattern (or lack thereof) observed in the quantum eraser experiments (http://grad.physics.sunysb.edu/~amarch/ ) ends up being the same if the eraser is present or not present. My thinking follows. Say N entangled photons are sent through the...
  15. L

    Help with Quantum Eraser experiments

    I read an article I found on the internet the other day about some Chinese scientists who have set a new speed record for Quantum Entanglement or (Spooky action at a distance). I have since been fascinated by Quantum Mechanics and am trying to understand it (as best I can). I am not a scientist...
  16. G

    Quantum Eraser Experiment: Fact or Fiction?

    How accurate is this statement: After the photon passes through the detector, it then passes through the eraser. The eraser is an electronic device that alters the wave-function of the photon, just like the detector is an electronic device that alters the wave-function of the photon. This guy...
  17. N

    Quantum eraser experiment - another thought experiment

    First of all, I am new to this forum but I already appreciate the great efforts invested here and the quality of many of the discussions! This is all pretty neat! My mind has just been blown by reading about the "Quantum Eraser" experiment.. It shows that it is the availability of the...
  18. I

    Double Slit Quantum Eraser, Really?

    Hello all, I have been reading about quantum entanglement on this webpage. It builds up to the quantum eraser where two entangled photons are produced using a BBO crystal, that have opposite polarity, with one going through a double slit to a detector and the other going to another detector...
  19. G

    Quantum eraser input polarization

    Hi all, I'm a bit confused about the polarization state of the photons after the BBO. I am aware that they are polarized orthogonally, but are they polarized according to a certain axis? The reason I'm asking is that one article I read seems to imply that that's not the case: i.e. the...
  20. J

    Delayed Choice Quantum Eraser Question

    I've heard we can rule out retro-causal effects if we think of the photon as both being a wave and a particle simultaneously. However I understand wave-particle duality as being the sum of all possible paths taken by a particle to a detector whilst being impossible to predict individual paths...
  21. A

    Quantum eraser and super luminous communication

    Let say we take each of the entangled photons and send one of them to receiver and one to transmitter located light years away. On receiver side photon is passing through double slit and hitting the screen. On transmitter side there is movable light stop placed at the same optical distance from...
  22. D

    Question on Decoherence and the Delayed Choice Quantum Eraser

    From what I have read online, decoherence is an irreversible process that gives the appearance of wave function collapse. For example, a macroscopic measuring device will always interact with the particle it is trying to measure, and the particle becomes entangled to this environment, and...
  23. A

    Question about a modified delayed choice quantum eraser. 2nd order interference?

    OK, a quick intro to the delayed choice quantum eraser is at wikipedia (http://en.wikipedia.org/wiki/Delayed...quantum_eraser ). I have attached a figure of the modified DCQE. In this setup there is no delay, there is no choice, and there is recombination of the idlers instead. In the...
  24. A

    Question about the delayed choice quantum eraser experiment

    In the delayed choice quantum eraser experiment of 2000 (DCQE http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser) which I have attached a simplified figure for, there is the use of a downconversion crystal which converts pump photons into two photons of half the energy, signal and idler...
  25. D

    Double Slit Experiment and Quantum Eraser

    Hello everybody, I am absolutely a novice in physics and although I generally have a good grasp of math I am pretty sure my knowledge of it is quite far from the one required by quantum physics. However, I am very interested to its main concepts and for this reason I am reading an...
  26. J

    Delayed Choice Quantum Eraser - double-photon explanation

    It is claimed that DCQE is equivalent to a single-photon double-slit setup. However, In this experiment, the 351.1nm Argon ion pump laser beam is divided by a double-slit, which means the actual photon rate is 1013 times higher than in a single-photon setup. Consequently, it makes it possible...
  27. F

    Delayed Choice Quantum Eraser and other oddities + their meaning

    Can someone list the different interpretations of QM and how they differ in their predictions on the nature of reality, and what wave function collapse really is? I keep flip flopping between thinking the weirdness in QM is just our human minds not comprehending reality correctly and...
  28. P

    Unraveling the Mystery of Quantum Eraser - Help Needed!

    Hi, I'm new here, and not *really* a physics student, just a guy trying to wrap his head around science by reading lots of books! Stuck on a well known theory, which in my head does not make sense, and hoping someone can clarify... Homework Statement A quantum Eraser - this works by...
  29. A

    Can Longer Waves Enhance the Quantum Eraser Effect at Home?

    Hello, some time ago I had a little idea which was posted here: http://asterisk.apod.com/viewtopic.php?f=39&t=21247 (see the last post) Maybe some minds about such possibility to explain the phenomenon?
  30. N

    Quantum Eraser and Its Implications

    Hi all. I am new here, and am very interested in developments in theoretical physics, though I am not trained as a scientist. I am hoping some of you can help answer a question. The quantum eraser experiment is said to prove that when which-path information is "erased" we get an...
  31. T

    Can someone explain the quantum eraser please?

    A double slit experiment which has two stages: first the experimenter marks through which slit each photon went, without disturbing their movement, and demonstrates that the interference pattern is destroyed. This stage shows that it is the existence of the "which-path" information which causes...
  32. S

    Entanglement in delayed choice quantum eraser (DCQE)

    In the delayed choice quantum eraser (DCQE), such as the walborn paper, link below: http://arxiv.org/PS_cache/quant-ph/pdf/0106/0106078v1.pdf" we try to find out the polarization/path via quarter wave plates (see diagram on page 7 of the paper) Now does not entanglement break (i.e...
  33. B

    Delayed Choice Quantum Eraser Experiment with a Black hole

    Assuming the setup of Kim, Yoon-Ho; R. Yu, S.P. Kulik, Y.H. Shih, and Marlan Scully (2000). "A Delayed Choice Quantum Eraser". Physical Review Letters 84: 1–5. arXiv:quant-ph/9903047. Bibcode 2000PhRvL..84...1K. doi:10.1103/PhysRevLett.84.1 (See...
  34. S

    Delayed choice quantum eraser – Yoon Vs Walborn experiment/paper

    Delayed choice quantum eraser – Yoon Vs Walborn experiment/paper is it true that in the Walborn experiment we manipulate p, but in Yoon paper we do not? The below link discusses the Walborn paper: http://grad.physics.sunysb.edu/~amarch/...
  35. R

    Implications of Quantum Eraser, Delayed Choice, etc.

    The behavior of the particle at the slits seemingly depends on what the photon encounters after the particle has passed through the slit(s). Does this prove that: 1. Particles can go back in time and do stuff? 2. Has quantum erasers been done using electrons or molecules like buckyball...
  36. StevieTNZ

    Quantum Eraser & 50% information eraser

    Hey there, I was pointed to the article attached, where I am meant to find an answer as to why in the proposed quantum eraser experiment, only 50% of the time 'information' would be erased - if that was the option chosen. On page five of the PDF, there seems to be some form of explanation...
  37. strangerep

    Rigorous treatments of double-slit , quantum eraser, etc.

    From a recent double-slit thread: Thank you for mentioning those papers! (Probably, I didn't notice the earlier mentions because I hardly ever read the endless "double-slit" threads. :-) The Fourier transform method occurred to me a while back as possibly a better way of deriving this...
  38. J

    Questions concerning Delayed Quantum Eraser

    After reading about the http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser" experiment, I thought of two interesting questions. Here I have taken http://en.wikipedia.org/wiki/File:Kim_EtAl_Quantum_Eraser.svg" and simplified it: In the normal delayed choice quantum eraser...
  39. K

    Misc. SciAm's DIY Quantum Eraser: Not Real?

    I recently tried a "DIY Quantum Eraser" experiment that was in the May 2007 issue of Scientific American (http://www.scientificamerican.com/article.cfm?id=slide-show-do-it-yourself-diy-quantum-eraser"). The basic idea is it's a double-slit experiment where photons going through each slit are...
  40. L

    Equipment for Quantum eraser experiment

    Does anyone know the full specs for those pump argon lasers used in the quantum eraser experiments? We're can I buy a used one? Also, is there a good place to buy the other equipment (lenses, crystals, etc) needed to perform the experiment? thanks! Lux
  41. D

    Interpretations of quantum eraser experiment

    Hi My interpretation of how observing the double slit experiment removes the interference pattern was that when (for example) an electron interacts with a photon, the electron is forced to be "at" that position, collapsing it's wavefunction. Then as the electron continues on towards the...
  42. G

    Resolution to the Delayed choice quantum eraser?

    I've been thinking about this weird experiment for a while and came up with a couple of insights: * This experiment presents before us the paradox between our concept of time, and the photon's nature of living outside of time. For the photon, the idler and the signal were measured at the...
  43. H

    Delayed choice quantum eraser experiment

    Hi, I would like to ask some questions regarding "delayed choice quantum eraser experiment". (I think it is possible for those who are familiar with this experiment to skip the text and go ahead into questions 1 and 2.) It is mentioned e.g. on these links...
  44. T

    Does the Quantum Eraser Experiment Disprove Local Hidden Variables?

    I have read a description of a Quantum eraser experiment: http://www.bottomlayer.com/bottom/kim-scully/kim-scully-web.htm I don't understand the technicalities, like the process how the entangled photon pair is generated. So things like that may solve my problem, or may not. What I'm not...
  45. C

    Does the Quantum Eraser Experiment Truly Erase Information or Alter Causality?

    Hello, info about quantum eraser experiment is at wikipedia and at http://grad.physics.sunysb.edu/~amarch/ I want to express my view of last part of this experiment and want to discuss whether there really is an "erasure" or a breakdown of causality even in the delayed case. the way the...
  46. I

    Delayed choice quantum eraser experiment in terms of MWI and/or BI

    I'm sure there's been a lot of posts on this before, but even after taking a look at some of them, this experiment is still eluding my understanding. I'm aware that there's no backwards causation--and that the eraser causes interference by random 'categorization'--but I'm nonetheless...
  47. thenewmans

    Quantum Eraser and Delayed Choice Quantum Eraser

    I have read that these experiments have been successful and do not cause a disagreement with QM. But I can’t quite determine what was learned. So what did they prove or disprove? Is there a simple explanation? I thought they were designed to determine if wave collapse breaks either locality or...
  48. S

    Question about delayed choice quantum eraser

    I was reading about the Delayed Choice Quantum Eraser experiment here: bottomlayer.com/bottom/kim-scully/kim-scully-web.htm In this experiment the which-path info is erased or not at random AFTER the original (signal) photon hits the screen. The results of the screen are seen by the...
  49. M

    Coincidence and Single Rate detection in Quantum Eraser experiments

    I am having difficulty understanding why the single rate of detection (as opposed to the coincidence rate) is unaffected during Quantum Eraser experiments. I'm looking at the great Kwait, Steinberg and Chiao paper: 'Observation of a "quantum eraser": A revival of coherence in a two-photon...
  50. I

    Is Timeless Light the Key to Understanding Quantum Eraser Experiments?

    The paper described at http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser rather intrigues me. While the results appear counter intuitive to us, the properties being tested are those of light, and since light travels at speed c, is it not the case that for light time stands still...
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