# What is Weak measurement: Definition and 13 Discussions

In quantum mechanics (and computation & information), weak measurements are a type of quantum measurement that results in an observer obtaining very little information about the system on average, but also disturbs the state very little. From Busch's theorem the system is necessarily disturbed by the measurement. In the literature weak measurements are also known as unsharp, fuzzy, dull, noisy, approximate, and gentle measurements. Additionally weak measurements are often confused with the distinct but related concept of the weak value.

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1. ### A Quantum weak measurement parameter estimation vs Classical Estimation

I am not an expert in quantum theory. I want to carry out some parameter estimation on a set of data I have. I have a model for the data with the parameter(s) of interest as variable(s). The data available is sporadic, meaning non-statistical or techniques involving no prior knowledge on the...
2. ### A Applications of weak measurement of quantum mechanics in other domains

This is a surface level question and I don't want to go into detail. Imagine an algorithm which when used with a sensor output gives the statistical moments of a variable in nature (for example mean and standard deviation of a variable). The sensor measures this once in a while (like once in a...
3. ### I Weak measurement and the measurement problem

When I think about it my biggest issue with the interpretation of QT can be boiled down to this question. There are the axioms of measurement in QT, which have their limiting nature and claim to be the only way to extract information from a quantum system - but that is just a claim with enough...
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### I What material is used in weak measurements for Young's experiment?

hello i try to look for some informations about the weak measurments that have been used in the Young's experiment. The slit was made with absorbent material to detect which slit the photon passes through but the fringe interferences are destroyed because of that. Which material is it? Does the...
5. ### Weak measurement quantum circuit

Homework Statement The circuit in the attached photo has a one-qubit operation ##U## which is controlled by the first qubit. The box with the meter and arrow denotes a measurement. If ##U=H## what is the probability of finding 0 or 1 in the final measurement of the second qubit? Homework...
6. ### B Does weak measurement cause mixed state?

Does a 'weak measurement' on the spin of an electron in a pure state put the electron in a mixed state of the previous state and the state of the measurement axis of the measurement?
7. ### B Weak measurement in double slit experiment gives which path

In 2012, experimenters showed that when two entangled photons separate and when one goes through the double slit, we can tell which slit it went through and see that they still created an interference pattern because the photon that it was entangled to tells us which slit it went through. What...
8. ### The No Cloning theorem vs weak measurement

Question: hypothesis Would it be possible to determine/ capture the total wave function of an ensemble using quantum tomography & weak measurement ? As seen in the following article.. Its been done on a photon.. My question is, could this same technique be done on an ensemble of particles...
9. ### Weak measurement with post selection

I'm reading stuff about weak measurements with post selection and its likely ability to improve computational performance. What I'm curious about is whether weak measurement is a real thing or not. There are many papers showing how to do the measurements and the theory behind them, and then...
10. ### Do weak measurement prove randomness is not inherent?

Weak measurement show that you can get "partial/probabilistic" which-way info and get a "partial" interference pattern. Deduction 1: Does this mean that weak measurements prove that we can control the degree of randomness? (either of individual photons or average of a thousands of photons)...
11. ### What really is a Weak Measurement?

Does it explain what occur during strong measurement or "approximately" solve the measurement problem? I'm asking because below it is mentioned that "it is this uncertainty that creates the uncontrollable, irreversible disturbance associated with measurement". Does it mean that measurement...
12. ### What do you think these Weak Measurement, Quantum Uncollapse Tests. Re-write QM?

What do you think these Weak Measurement, Quantum Uncollapse Tests. Re-write QM?? http://www.scienceagogo.com/news/20080706233709data_trunc_sys.shtml http://www.sciencedaily.com/releases/2008/08/080806140128.htm Are they going to re-write the quantum mechanics?
13. ### Consequences of Hardy's paradox and joint weak measurement

I read two articles recently and I am wondering if I have the correct interpretation of them. They deal with joint weak measurement and Hardy's paradox. Is the result of the "Direct observation of Hardy's paradox by joint weak measurement with an entangled photon pair" paper indicating...