Observation of a ‘‘quantum eraser’’: A revival of coherence in a two-photon interference experiment

Physical Review A (Impact Factor: 2.81). 07/1992; 45(11):7729-7739. DOI: 10.1103/PhysRevA.45.7729
Source: PubMed


We have observed an effect known as a quantum eraser, using a setup similar to one previously employed to demonstrate a violation of Bell's inequalities. In this effect, an interfering system is first rendered incoherent by making the alternate Feynman paths which contribute to the overall process distinguishable; with our apparatus this is achieved by placing a half wave plate in one arm of a Hong-Ou-Mandel interferometer so as to rotate the polarization of the light in that arm by 90°. This adds information to the system, in that polarization is a new parameter which serves to label the path of a given photon, even after a recombining beam splitter. The quantum ``eraser'' removes this information from the state vector, after the output port of the interferometer, but in time to cause interference effects to reappear upon coincidence detection. For this purpose, we use two polarizers in front of our detectors. We present experimental results showing how the degree of erasure (which determines the visibility of the interference) depends on the relative orientation of the polarizers, along with theoretical curves. In addition, we show how this procedure may do more than merely erase, in that the act of ``pasting together'' two previously distinguishable paths can introduce a new relative phase between them.

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Available from: Aephraim Steinberg, Jan 05, 2015
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    • "There have been many quantum optics experiments involving two photon entangled states and quantum eraser arrangements to prove the complementarity arguments above. Three of the better ones are [9] [10] [11]. One experiment in particular by Zeilinger's group [12] is worthy of a special note. "
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    ABSTRACT: This paper explains the delayed choice quantum eraser of Kim et al. in terms of the transactional interpretation of quantum mechanics by John Cramer. It is kept deliberately mathematically simple to help explain the transactional technique. The emphasis is on a clear understanding of how the instantaneous "collapse" of the wave function due to a measurement at a specific time and place may be reinterpreted as a gradual collapse over the entire path of the photon and over the entire transit time from slit to detector. This is made possible by the use of a retarded offer wave, which is thought to travel from the slits (or rather the small region within the parametric crystal where down-conversion takes place) to the detector and an advanced counter wave traveling backward in time from the detector to the slits. The point here is to make clear how simple the Cramer transactional picture is and how much more intuitive the collapse of the wave function becomes if viewed in this way. Also any confusion about possible retro-causal signaling is put to rest. A delayed choice quantum eraser does not require any sort of backward in time communication. This paper makes the point that it is preferable to use the Transactional Interpretation (TI) over the usual Copenhagen Interpretation (CI) for a more intuitive understanding of the quantum eraser delayed choice experiment. Both methods give exactly the same end results and can be used interchangeably.
    Foundations of Physics 01/2015; DOI:10.1007/s10701-015-9956-8 · 1.03 Impact Factor
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    • "Again, both the causal interpretation [38] and its extension to Boson fields [31] can explain the Wheeler delayed-choice experiment in a causal, non-paradoxical way. A further push of conceptual boundaries occurred with the introduction of quantum erasure experiments [39] [40] [41] [42] [43] [44] [45]. Perhaps the best example is the quantum eraser experiment of Kim et al [45]. "
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    ABSTRACT: I argue that quantum optical experiments that purport to refute Bohr's principle of complementarity (BPC) fail in their aim. Some of these experiments try to refute complementarity by refuting the so called particle-wave duality relations, which evolved from the Wootters-Zureck reformulation of BPC (WZPC). I therefore consider it important for my forgoing arguments to first recall the essential tenets of BPC, and to clearly separate BPC from WZPC, which I will argue is a direct contradiction of BPC. This leads to a need to consider the meaning of particle-wave duality relations and to question their fundamental status. I further argue (albeit, in opposition to BPC) that particle and wave complementary concepts are on a different footing than other pairs of complementary concepts.
    Foundations of Physics 08/2014; DOI:10.1007/s10701-015-9959-5 · 1.03 Impact Factor
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    • "After the two slits, a photon is in a state that entangles the spatial slit states and the polarization states which might be represented as: |s1 ⊗ |h + |s2 ⊗ |v (for a discussion of this type of entanglement, see [7]). But as this superposition evolves, it cannot be separated into a superposition of the slit-states as before, so the interference disappears. "
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    ABSTRACT: There is a very common fallacy, here called the separation fallacy, that is involved in the interpretation of quantum experiments involving a certain type of separation such as the: double-slit experiments, which-way interferometer experiments, polarization analyzer experiments, Stern-Gerlach experiments, and quantum eraser experiments. It is the separation fallacy that leads not only to flawed textbook accounts of these experiments but to flawed inferences about retrocausality in the context of "delayed choice" versions of separation experiments.
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