# measurement

The Fundamental Theorem of Quantum Measurement is stated as follows: Every set of operators $\{ A_n \}$ $n =1,...,N$ that satisfies $\sum_n... Thread by: Danny Boy, Feb 5, 2018, 2 replies, in forum: Quantum Physics 2. Thread ### A Fundamental Theorem of Quantum Measurements The Fundamental Theorem of Quantum Measurements (see page 25 of these PDF notes) is given as follows: Every set of operators$\{A_n \}_n## where...
Thread by: Danny Boy, Jan 24, 2018, 78 replies, in forum: Quantum Physics

### A Defining Krauss operators with normal distribution

I am interested in defining Krauss operators which allow you to define quantum measurements peaked at some basis state. To this end I am...
Thread by: Danny Boy, Jan 22, 2018, 1 replies, in forum: Quantum Physics

### B Least / Smallest / Minimum Detectable Difference

In scientific experiment, we often have a physical property that can change but have no detectable impact on the measurement. For example,...
Thread by: Roger Dodger, Jan 21, 2018, 12 replies, in forum: Set Theory, Logic, Probability, Statistics

### I Error in the average of same-value measures

My question is simple, and I'm only asking it because most places talk about more advanced problems than this one: I've measured the radius of a...
Thread by: Guilherme Franco, Dec 8, 2017, 6 replies, in forum: General Physics

### QM: Purity, two-outcome measurements

1. The problem statement, all variables and given/known data [ATTACH] 2. Relevant equations in addition to those provided in the questions, I...
Thread by: alc95, Nov 13, 2017, 1 replies, in forum: Advanced Physics Homework

### I Velocity measurement by a stationary observer in GR

In almost general case, the space-time metrics looks like: ds^2 = g_{00}(dx^0)^2 + 2g_{0i}dx^0dx^i + g_{ik}dx^idx^k,...
Thread by: sergiokapone, Oct 25, 2017, 46 replies, in forum: Special and General Relativity

### A Falsifications and constraints due to GW measurements

This thread is to serve as - a collection of theories that have been falsified by and/or have had new constrained placed on them by the ongoing...
Thread by: Auto-Didact, Oct 22, 2017, 15 replies, in forum: Astronomy and Astrophysics

### B Understanding Measurements / Collapse

I'm trying to understand the impact of past measurements, and when measurements occur. As I understand it, in the simplest case, you've got a...
Thread by: 1977ub, Oct 10, 2017, 49 replies, in forum: Quantum Physics

### A How can i measure high magnetic fields?

Hello! I've made a lot of research about measurement of high magnetic fields - such us 1T - 2T and I can't find sensors for this range. I'm...
Thread by: Misiak, Sep 11, 2017, 6 replies, in forum: General Physics

### I Concerning the Nature of Quantum Measurement...

I'm well aware of the common adage and quantum fact that, until a particle is measured by some sort of instrument, it exists in a state of...
Thread by: PotentialReasoning, Jul 3, 2017, 4 replies, in forum: Quantum Physics

### A Field strength measurement and continuity

Something about the theory of quantum measurement/collapse in the case of quantum fields... Suppose I have a field, either a scalar, vector or...
Thread by: hilbert2, Jun 28, 2017, 8 replies, in forum: Quantum Physics

### B Basic question about double slit interferance

I am new here so I will start with a warming up question :) My question is very trivial here we go: In double slit experiment when shooting one...
Thread by: Ostrados, Feb 24, 2017, 7 replies, in forum: Quantum Physics

### I Commuting observables vs. exchanging measurements

Hi. I'm afraid I might just be discovering quite a big misunderstanding of mine concerning the meaning of the expectation value of a commutator...
Thread by: greypilgrim, Feb 21, 2017, 5 replies, in forum: Quantum Physics

### Measuring AC current with an oscilloscope.

I have a technical question, for research purposes. I have LED that we probe in AC mode. To measure the applied voltage in AC and the...
Thread by: FM79, Feb 5, 2017, 7 replies, in forum: Electrical Engineering

### How do I convert cubic picometer to cubic centimeter?

Part of the question says: An unit cell has a cell edge of 288 pm. I got to the part where volume (288 pm)^3 = (288 x 10^-10 cm)^3 I have no idea...
Thread by: Rajdeep Biswas, Dec 23, 2016, 3 replies, in forum: Introductory Physics Homework

### I Many measurements are not covered by Born's rule

Why do you have what you call a "Thermodynamic Interpretation"? My ''thermal interpretation'' is an interpretation of quantum mechanics in...
Thread by: A. Neumaier, Nov 20, 2016, 96 replies, in forum: Quantum Physics

### B Do we measure the particle or the wavefunction?

It seems to me that we don't measure a particle because a particle doesn't have an objective existence independent of the wave function or does...
Thread by: quantumfunction, Oct 30, 2016, 15 replies, in forum: Quantum Physics

### I Electrodes liquid contact electromagnetic flow meter?

Hello, I'm interested in building a small non-invasive battery powered device that wraps around a pressured 1/2" pipe for measuring potable...
Thread by: thomas49th, Oct 30, 2016, 2 replies, in forum: General Physics

### How to differentiate GHZ state and W state?

Good day, I try to differentiate GHZ-state and W-state using three tangle. Suppose The value three tangle for GHZ-state equal to 1 while W-state...
Thread by: munirah, Oct 24, 2016, 1 replies, in forum: Advanced Physics Homework

### B Why can't one metre be more than one metre?

Hello, Recently, I have been trying to work on some philosophy that I am developing, and the subject of measurement has come up. My question...
Thread by: jomsur, Sep 20, 2016, 4 replies, in forum: General Physics

### B Counterfactual definiteness and correlation

If we assume there is no counterfactual definiteness, would that mean that measurements on entangled particles needn't be correlated, for if you...
Thread by: entropy1, Jun 17, 2016, 23 replies, in forum: Quantum Physics

### I Macro state of a measurement device and correlation

I have a question that seems to reflect my main concern with QM. Here it is: Consider a series of polarisation-entangled photon pairs that are...
Thread by: entropy1, Jun 14, 2016, 8 replies, in forum: Quantum Physics

### I Is there a 'memory-effect' of measuring devices?

If I'm correct, a series of with respect to some property entangled particles exhibits a correlation between several measurements of that property...
Thread by: entropy1, Jun 7, 2016, 18 replies, in forum: Quantum Physics

### B Has any experiment actually measured PI to many places?

Ok, This probably seems a silly question, but has there been any 'serious' attempt to measure Pi PHYSICALLY, like in a lab, using say a light...
Thread by: squirrlmcduckles, May 31, 2016, 16 replies, in forum: General Physics

### B Nature of collapse / does collapse exist?

I learned that the moment a wavefunction collapse takes place is a matter of interpretation. So, I suppose the phenomenon 'wavefuntion collapse'...
Thread by: entropy1, May 25, 2016, 34 replies, in forum: Quantum Physics