What is Quantum measurement problem: Definition and 21 Discussions

In quantum physics, a measurement is the testing or manipulation of a physical system in order to yield a numerical result. The predictions that quantum physics makes are in general probabilistic. The mathematical tools for making predictions about what measurement outcomes may occur were developed during the 20th century and make use of linear algebra and functional analysis.
Quantum physics has proven to be an empirical success and to have wide-ranging applicability. However, on a more philosophical level, debates continue about the meaning of the measurement concept.

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  1. Gary Venter

    I Measurement problem - will this work?

    Consider the measurement problem for an electron in a single-slit experiment done one electron at a time. There are two interlinked questions, but some consider just one of them to be the actual measurement problem. The first question is concentration - a fairly uncertain distribution condenses...
  2. riballoon

    B Heisenberg's Uncertainty Principle and determinism

    As I understand it the principle states that the more accurately you measure one factor of an object, for example speed, the less you can tell of any other factors, for example position. To me this seems we will every only be able to measure an approximation of reality and thus determinism...
  3. Pipsqueakalchemist

    I Is quantum mechanics imply nature is deterministic or probabilistic?

    So initially I thought quantum mechanics was deterministic in the equations but was probabilistic in measurement. I’m aware of bell’s inequality which rules out hidden variables unless you assume super determinism. But recently I’ve come across something called decoherence and some people have...
  4. H

    I Waveform collapse due to entaglement cascade

    In my limited understanding of the quantum measurement problem, I am imagining the whole thing as corresponding to a kind of "weighting down" by a cascade of entaglement. Here is my very simple understanding of the quantum measurement problem: A waveform (Schrödinger equation) describes the...
  5. Mr_Allod

    Commutation and Measurement of Observables

    Hello there, I am having trouble with part b. of this problem. I've solved part a. by calculating the commutator of the two observables and found it to be non-zero, which should mean that ##\hat B## and ##\hat C## do not have common eigenvectors. Although calculating the eigenvectors for each...
  6. A. Neumaier

    I The thermal interpretation of quantum physics

    A complete description of the thermal interpretation of quantum physics can be found in my just finished papers (for the bare bones, see Section 2.5 of Part II) Foundations of quantum physics I. A critique of the tradition, Foundations of quantum physics II. The thermal interpretation...
  7. Johny Boy

    A Decoherence of measurement outcomes

    Suppose we have a quantum system ##Q## with an initial state ##\rho^{(Q)}##. The measurement process will involve two additional quantum systems: an apparatus system ##A## and an environment system ##E##, hence giving the initial state of the system ##\rho^{(AEQ)} = \rho_{0}^{(AE)}\otimes...
  8. Johny Boy

    A Using feedback in quantum measurements

    If we consider an efficient measurement performed on a system in a pure state. How would we use feedback (by applying to the system a unitary operator that depends upon the measurement result), to prepare the system in the same final state for every outcome of the measurement (this can be done...
  9. E

    I General Questions Related to Quantum Measurement

    I've recently been wondering about the notion of measurement in quantum mechanics. While I'm aware that understanding and precisely defining the concept of a quantum mechanical measurement is at the heart of interpreting the subject, I would like some feedback on some aspects of this topic I...
  10. pittsburghjoe

    I Explanation for the Quantum Measurement Problem?

    Do we yet have an explanation for the Measurement Problem that Einstein would have been satisfied with?
  11. munirah

    What is the Relationship Between Concurrence and Three Tangle in Quantum States?

    Good day, May anyone help me to confirm the formula use for three tangle using concurrence. From my reading, three tangle, $$\tau=\tau_{A(BC)}-\tau_{AB}-\tau_{AC}$$ and it can be related to concurrence $$\tau=C^2_{A(BC)}-C^2_{AB}-C^2_{AC}$$ and I used formula for C is...
  12. Giulio Prisco

    A Given decoherence, do we still need random quantum jumps and

    This thread was posted and discussed on Physics Overflow, I am re-posting it here to hear other opinions. http://www.physicsoverflow.org/36063/given-decoherence-still-random-quantum-jumps-interpretations? Environmental decoherence explains how the wavefunction of a quantum system q, as a result...
  13. munirah

    How to calculate negativity measurement of quantum state?

    Good day, From my reading according to negativity for tripartite state, it is given as below; $$N_{ABC}(\rho)=(N_{A-BC}N_{B-AC}N_{C-AB})^{1/3}$$ with $$N_{I-JK}=-2\Sigma_i\sigma_i(\rho^{TI})$$ where $$\sigma_i(\rho^{TI})$$ being the negative eigenvalues of $$\rho^{TI}$$, the partial...
  14. PhysicsKid0123

    Measurement-Free Interactions (MFI)

    So I have not been able to find too much information about this. Specifically in the context of the double slit experiment. I've seen just about the only video on Youtube that tries to explain this, but I did not understand-- I felt like somethings were not explained. I am acquainted with why a...
  15. J

    Heisenberg Uncertainty Principle clarification

    I found these two examples in a books which demonstrate Heiseberg's uncertainty relation...
  16. M

    What Constitutes a Quantum Measurement in Liquid Helium Experiments?

    I just found out about this via Twitter: http://phys.org/news/2014-10-function-electron.html I'm too tired to have got my head around all the details, but it looks as if there's a fascinating new experimental perspective on what a "measurement" in QM actually is. DOI for the original journal...
  17. M

    Superposition and retrocausality

    Hello guys, I made this analogy for double slit experiment. I would like to share this idea and I would like to hear your opinions and ideas. Thank you. I apologize for any typos or bad grammar, I am not native english speaker. Here it is: Analogy for wave collapse I am using term KNOWER...
  18. M

    Quantum Measurement Problem: Nature of Matter or Nature of Probability?

    The objective of this post is to: (i) generate a discussion of whether results of the double-slit experiment address solely the nature of matter, or do the results also address the nature of probability; and (ii) to determine if there have been any comparably structured experiments outside of...
  19. S

    Quantum measurement problem

    Do you believe that "conscious" observation has anything to do with "collapsing" superimposed quantum states, or do you simply believe that interaction with a macroscopic, or sufficiently large system, is what causes superimposed quantum states to collapse? Why?
  20. wolram

    Quantum measurement problem paper

    http://arxiv.org/PS_cache/quant-ph/pdf/0506/0506100.pdf Title: A New Ontological View of the Quantum Measurement Problem Authors: Xiaolei Zhang Comments: 37 pages. US Naval Research Lab memorandum report NRL/MR/7218--05-8883, paper to be presented at the Albert Einstein Century conference...
  21. G

    The Quantum Measurement Problem and Decoherence

    Hi, I am reading Brian Greene's new book "The Fabric of the Cosmos". In the book, Brian Greene talks about the Quantum Measurement Problem, different interpretations of QM, decoherence, etc... Rather than attributing the collapse of the probability wave to things like conscious or human...