# What is Quantisation: Definition and 28 Discussions

Quantization, involved in image processing, is a lossy compression technique achieved by compressing a range of values to a single quantum value. When the number of discrete symbols in a given stream is reduced, the stream becomes more compressible. For example, reducing the number of colors required to represent a digital image makes it possible to reduce its file size. Specific applications include DCT data quantization in JPEG and DWT data quantization in JPEG 2000.

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1. ### I Is There Only One True Outcome in the Many-Worlds Interpretation?

Suppose we have a photon in superposition of reaching detector A or detector B. Then, in Everett-worlds, both outcomes (detection at A/detection at B) are true, but in different worlds (##|U_x\rangle|x\rangle##). But if we observe the law of conservation of energy and the quantisation of the...
2. ### How Many Bits Per Sample for a 10dB SNR with a Uniform Quantiser?

Homework Statement [/B] An analogue signal is uniformly distributed from -4,4. Design a uniform quantiser with minimum number of bits per sample, such that the signal to quantisation noise is at least 10dB. How many bits are required per sample? What is the mean square (quantisation) error for...
3. ### B Quantisation of light and Doppler effect

Light consists of quanta(small packets of energy). Then how do we explain doppler effect of light the same way we do for sound? What is the valid explanation of light doppler effect which is consistent with the photon picture?
4. ### How to deduce the solution of normal modes of a cavity?

Homework Statement In the book "Quantum Optics" written by Scully and Zubairy, there is an equation (1.1.5). The equation is presented directly and not explained how to be deduced. The content is as follows. Homework Equations The Attempt at a Solution I know the solution should have the form...
5. ### I About quantisation of energy

Why is E directly proportional n squared when we consider particle in a box but when we consider electron in a hydrogen atom its E inversely proportional n squared.
6. ### A Canonical quantisation of the EM field

I have just gone through chapter 14 on the QFT for the gifted amateur by Lancaster and Blundell. Quantising the electromagnetic field results in the Hamiltonian: $$\hat{H}=\int d^3p \sum^{2}_{\lambda=1} E_p \hat{a}^\dagger_{p\lambda} \hat{a}_{p\lambda}$$ with ##E_p=|p|##. In this post ##p##...
7. ### I Can diffraction be explained by quantisation?

I was wondering if the diffraction pattern through a single slit could be explained as a consequence of quantisation of momentum transverse to the main direction of travel. I know that momentum gets quantised on confinement so does the confinement in a slit quantise the momentum so that only...
8. ### Is the Hamiltonian of a string given by a sum of harmonic oscillators?

Homework Statement This problem is a continuation of the problem I posted in this thread: https://www.physicsforums.com/threads/equation-of-motion-from-a-lagrangian.867784/ (We have set the mass per unit length in that question to ##\sigma## = 1 to simplify some of the formulae a little.)...
9. ### I Schrödinger Potential Fields with no Energy Quantisation?

The solution to the One-Dimensional Time-Independent Schrödinger equation for an electric potential field of constant value is an exponential function, and its energy eigenvalue can have any value, it is not quantised. Are there any other potential field functions whereby the energy of the...
10. ### Ladder operators in Klein -Gordon canonical quantisation

The quantum Klein-Gordon field ##\phi({\bf{x}})## and its momentum density ##\pi({\bf{x}})## are given in Fourier space by ##\phi({\bf{x}}) = \int \frac{d^{3}p}{(2\pi)^{3}} \frac{1}{\sqrt{2 \omega_{{\bf{p}}}}} \big( a_{{\bf{p}}} e^{i{\bf{p}} \cdot {\bf{x}}} + a^{\dagger}_{{\bf{p}}}...
11. ### Second quantisation formula (electron-phonon coupling)

Hello, I can't understand where this formula ((8.5), Rössler, Solid State Theory, Springer) comes from (see attached file). The label l stands for the electrons positions and c and c dagger are the free electron creation and annihilation operator. This expression is used to write the linear...
12. J

### What Are Some Current Topics in Physics That Interest John Salkeld?

The title above give my name. I am a pure maths PhD with an interest in physics and geometry. I am currently studying physics for fun and I am very interested in current progress. I am especially interested in quantisation of space time, holographic theories and dualities. Regards John
13. ### Why is charge quantized and unable to exist in fractional or decimal values?

Homework Statement Quantisation means charge always exist in integral multiples of magnitude of charge of electron and to put it mathematically we say q = ne, where n is an integer 1,2,3,4 ... -1,-2,-3,... etc. Numerous print and web materials say that charge cannot exist in fraction or...
14. ### Proof for quantisation of electrons energy around an atom?

What is the proof for quantisation of electrons energy around an atom?
15. ### Exploring 2nd Quantisation in the WDW Equation

In QFT the background field is 2nd Quantised as opposed to remaining classical What exactly gets 2nd Quantised in the WDW Equation Geometry of SpaceTime Or Matter Energy Or Gravity Or Some combination of the above, if so what is the combination
16. ### Nth Quantisation and Cosmology

This article on 4th Quantisation http://arxiv.org/pdf/1304.0259v3.pdf Takes the WDW equation to 3rd Quantisation to understand the spawning of universes from false vacua from a Multiverse And Furthermore goes to 4th Quantisation to investigate multiverse interactions Is this the best way to...
17. ### Z-direction. Quantisation axis

I'm a bit confused with this concept of quantisation axis. ##|+\rangle## and ##|-\rangle## spin. And operators ##\hat{S}^+=\hat{S}_x+i\hat{S}_y## and ##\hat{S}^-=\hat{S}_x-i\hat{S}_y## are rising and lowering operator of spin projection. Why z-axis. How is measured that?
18. ### Can Moving a Hydrogen Atom by an Angstrom Alter Its Mass?

Not sure if this should be in the quantum or classical forum, but as gravity has not been shown to be quantised yet... My question is this, seeing as there is no quantised theory of gravity yet, that would mean that if a single atom of say hydrogen residing on the surface of the Earth was moved...
19. ### What Is the Rydberg Constant Value for Calculating Hydrogen Atom Transitions?

Homework Statement The ionisation energy of a single hydrogen atom is 13.6 eV. The application of Bohr quantisation to the hydrogen atom results in the stationary states having discrete energies given in terms of a positive integer n according to E=-RB/n2 where RB is the Rydberg...
20. ### Importance of pi and phi for canonical quantisation

Homework Statement Explain in words the importance of pi(x) and phi(x) for the canonical quantisation programme. Homework Equations none The Attempt at a Solution This is a past paper exam question, which I would appreciate some clarity on. As a proposed suggestion: pi(x) and...
21. ### List out the evidences of quantisation of charge.

Homework Statement List out the evidences of quantisation of charge. Homework Equations The Attempt at a Solution Like, what evidence is there for charge quantisation?
22. ### Light-cone gauge quantisation of point particle

Dear all, I'm reading Polchinski's text of string theory. In section 1.3, he demonstrates how to quantize the free point particle in the light-cone gauge. I'm confused with a step in the follows. Begin with the action, S = \frac{1}{2}\int d\tau\left(\eta^{-1}\dot{X}^\mu\dot{X}_\mu -...
23. ### Quantisation of EM field

Particle energy and momentum are obtained from the wave function as eigenfunctions of the spatial and time derivative operators. Is this true of ElectroMagnetic fields? In other words are E and B eigenfunctions of a differenial operator? I can see that E and B could be interpreted as a...