In physics, a quantum (plural quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a physical property can be "quantized" is referred to as "the hypothesis of quantization". This means that the magnitude of the physical property can take on only discrete values consisting of integer multiples of one quantum.
For example, a photon is a single quantum of light (or of any other form of electromagnetic radiation). Similarly, the energy of an electron bound within an atom is quantized and can exist only in certain discrete values. (Atoms and matter in general are stable because electrons can exist only at discrete energy levels within an atom.) Quantization is one of the foundations of the much broader physics of quantum mechanics. Quantization of energy and its influence on how energy and matter interact (quantum electrodynamics) is part of the fundamental framework for understanding and describing nature.
The emission spectrum or resonance fluorescence for a quantum dot, atom or defect center are discussed in many quantum optics textbook, for example see "Quantum Optics" by Marlan O. Scully and M. Suhail Zubairy Chapter 10 , "Quantum Optics" by D. F. Walls and Gerard J. Milburn Chapter 10 and...
We know that both momentum and position can not be known precisely simultaneously. The more precisely momentum is known means position is more uncertain. In fact, as I understand quantum mechanics, position probability never extends to 0% anywhere in the universe (except at infinity) for any...
In non relativistic quantum mechanics, the expectation value of an operator ##\hat{O}## in state ##\psi## is defined as $$<\psi |\hat{O}|\psi>=\int\psi^* \hat{O} \psi dx$$.
Since the scalar product in relativistic quantum has been altered into $$|\psi|^2=i\int\left(\psi^*\frac{\partial...
Hello, I am currently studying about entanglement on spin-1/2 chains and I was able to find some information about the mathematical point of view of concurrence but I can't understand the physical meaning of it . Can somebody help me, please?
Hi, has anyone tried to build "quantum GR", using the expectation value of |Psi(x)> as a "quantum ruler" and |Psi(t)> as a "quantum clock" to build up the idea of a "quantum metric"?
My article has been published in Entropy .
Abstract:
Schrödinger noticed in 1952 that a scalar complex wave function can be made real by a gauge transformation. The author showed recently that one real function is also enough to describe matter in the Dirac equation in an arbitrary...
I am trying to learn about quantum chemistry for the purpose of understanding electronic structures of nanomaterials, or perhaps more generally some theoretical computational approaches to understanding interactions of nanomaterials/small molecules and high energy (keV to MeV) radiation. I'm...
As of today, there are plenty of time machine mathematical models based on general relativity theory (warp drives, wormholes), but few ones based on quantum physics. However, back in 2010, Seth Lloyd wrote: "quantum mechanics supports a variety of counter-intuitive phenomena which might allow...
I'm sure most will be familiar with the well-known ball and cup trick. The dynamics of the game itself are unimportant, we just need to have the image of 5 cups with a single ball being revealed when the relevant cup is lifted.
The Set-up
Imagine a machine which has a conveyor belt coming out...
I heard something today about the "informational interpretation" of quantum mechanics and a phrase used was "it from bit." Is there actually such a thing? What does it mean, and how is it distinguished from other interpretations like MWI or Copenhagen?
hello: I don’t know where to post this and I think this is as good a place as any here.
question: does quantum entanglement explain how we are?
I am having trouble Even trying to express the question above. But, I just viewed PBS space-time series 6 episode eight: “how do quantum states...
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.040403
In QM, I was taught that the imaginary unit ##i## in wave functions is merely a mathematical tool. It has no physical meaning. We can always take the real part of the complex wave functions. Therefore, there should be some...
* The general formula for the magnetic moment of a charge configuration is defined as ##\vec{\mu} = \frac{1}{2} \int \vec{r} \times \vec{J} \,d^3r##* For an electron it's said that the correct equation relating it's spin and magnetic moment is is
##\vec{\mu} =g\frac{q}{2m}\vec{S}##
* It's...
Physicists have proposed linking a global network of cesium clocks in a phase-coherent entangled state, for example in the article A Quantum Network of Clocks (arXiv:131045v1). My audience would like to know how better synchronization or more accurate timekeeping would lead to advances in our...
in classical physics, when a charged particle oscillates, it emits an electromagnetic wave, and the frequency of the wave depends on the frequency with which the particle oscillates.
But in quantum physics, when an excited atom emits a photon, the energy of the photon depends on the magnitude of...
I work in IT and am a layman in the quantum world. I have obviously misunderstood something in my amateur reading of quantum, but if someone could explain my mistake in the above scenario it might be very insightful for me! Forgive me if the terminology is not correct - or if indeed lay folks'...
Under several historical experiments, measurement back-action has exhibited the ability the suppress a system's transitions to other states, especially when measurements are taken at a high frequency in time. This phenomena has become known as the Quantum Zeno Effect. In short, a quantum...
Hi Fellas! My first post after a long hiatus from forums. Feeling nostalgia (this is the place where it all began, my fuel for quantum fascination so to speak).
I am revisiting the mathematical formulation of quantum mechanics with the dimensional (MLT) perspective. I want to understand what...
I was just wondering how much work is being done in the field of quantum gravity nowdays. Is there still a huge volume of research published on the topic? Are we closer to a "solution" nowdays than we were a few years ago? And also, what exactly would constitute a solution to such problem?
I tried to find states in direct method using ##\frac{E}{E_0}=\:nx^2+ny^2+nz^2## and ##100\:<nx^2+ny^2+nz^2\:<\:136##
But it was too long, found it using phi approximation there are around 300 energy states, and Python find around 271 states using direct method but I need manual or recursive...
Hello everyone,
I wanted some help deciding which elective to choose. I am a junior and for my next semester I have the option to pick either Differential Geometry-I or Quantum Information. I am confused which one to choose. We will be doing QMII as a compulsory course next semester and I have...
Summary:: I am in the highest level Quantum class at my university- technically considered a grad class. I am an undergrad and need advice on just how to learn it. What study tips? Good Youtubers? Physical simulations? Anything that helped you in quantum mechanics.
Hello! I am an undergrad...
Hi, I'd like to clarify the following terminology
(Fradkin, Quantum Field Theory an integrated approach)
"carry the quantum numbers of the representation of the gauge group":
Does the author basically mean that the wilson loop is a charged operator, in a sense that it transforms non-trivially...
I understand that string theory has almost no testable predictions, however loop quantum gravity is an enticing candidate for only quantum gravity and it doesn't explain much of symmetry, constants, mixing angles etc in Standard model. There is obviously not enough evidence to create a full...
Consider the following scenario: a space station is put into orbit, which is absurdly well shielded from all sorts of radiation, a.k.a. "a box". You cannot make any effective observation of what the astronaut inside is up to. (This postulate may be implausible, but in the age of "weakly...
https://www.newscientist.com/article/2302337-tardigrade-is-first-multicellular-organism-to-be-quantum-entangled/
A tardigrade has been quantum entangled with a superconducting qubit – and lived to tell the tale. It is the first time a multicellular organism has been placed in this strange...
According to the uncertainty principle, when we measure a micro-object with a measuring device, we cannot predict what value the device will show. But if we knew exactly the wave function of this device, together with the wave function of the micro-object, could we exactly predict the result of...
Summary:: I’m a beginner trying to get into Quantum Physics, and want some good resources (e.g. books) to get me started.
Hi everyone!
I’m a beginner trying to get into Quantum Physics, and want some good resources (e.g. books) to get me started.
I have a very basic knowledge of physics (10th...
Hi!
I want to self study some of quantum mechanics so i need introductory textbook. I've taken courses on linear algebra that covers all "Linear algebra done right" by Sheldon Axler, multivariable calculus, two courses on general physics and the basics of differentials equations.
I really like...
Summary:: I'm trying to understand the meaning behind the answer of 2.34... but I haven't taken a quantum class yet so I'm utterly lost.
So I took this physics class that's teaching us python and for our final project our teacher assigned random problems to work out, well I got stuck with a...
Hello folks, I am currently studying from Griffiths' Introduction to Quantum Mechanics and I've got a doubt about good quantum numbers that the text has been unable to solve.
As I understand it, good quantum numbers are the eigenvalues of the eigenvectors of an operator O that remain...
If gravity is the affect of time dilation because of the distance from the bottom of an object to the top then wouldn’t that mean that gravity doesn’t exist at the quantum level?
How do we map experimental measurements of quantum fields, such as those seen in accelerators, to the theory's mathematical formalism? When we see images of particle tracks produced in accelerators such as the LHC, I think it's safe to say a measurement (or series of measurements) has been...
I have some questions to this Ansatz and I would really appreciate it if I can get some insight:
1. What is the current status of gate fidelity and what are the current struggles to improve it?
2. Same question but with coherence times.
3. What are the current issues with scalability?
4. Could...
Can you please suggest a good introductory statistical and quantum mechanics book which can be self studied.
My math background :
I've done multivariate calculus, vector calculus, linear algebra ,some complex analysis all at the usual undergraduate level.
The books I've self studied thus far...
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...
##x## can be discretized as ##x \rightarrow x_k ## such that ##x_{k + 1} = x_k + dx## with a positive integer ##k##. Throughout we may assume that ##dx## is finite, albeit tiny.
By applying the Taylor expansion of the wavefunction ##\psi_n(x_{k+1})## and ##\psi_n(x_{k-1})##, we can quickly...
I have some basic questions about mixed states and entanglement.
1. Do mixed states always imply that the states are entangled and vice versa?
2. Can mixed states ever be separable?
3. Does interference have anything to do with entanglement?
In terms of Density Matrices, ρ = |ψ><ψ|:
4...
Of course, this question consisted of two parts. In the first part, we needed to calculate the first-order correction. It was easy. In all the books on quantum mechanics I saw, only first-order examples have been solved. So I really do not know how to solve it. Please explain the solution method...
(I am not sure which forum this post belongs to. Hope someone kindly helps me move it to a proper forum.)
In papers, for example, here, here, and here, the authors start from the Lagrangian for matters and gravitational fields, then Dirac's constrained canonical quantization is used. They...
Very confused about this article and the experiment it's based on. I'm not very knowledgeable on this, but I'm very confused on what's happening here. It seems extremely weird to me
I'am interested in the notation of the approximation in quantum phase estimation algorithm.
In the literature there are different definitions, which I divide into two cases here. Both different in their definition of the ##\delta##. In both cases I start with a quote of the source and show an...
Hi, there. I am interested in quantum gravity. But I am not sure how to find review papers about its recent developments. I tried "quantum gravity" on google scholar. But I could not find a suitable review other than that about loop quantum gravity. I am not sure what are the other approaches to...