Quantum Theory

Let say we will bring negatively charged metal plate in contact with p-type semiconductor. Will electrons from charged plate enter p-type semiconductor and recombine with holes under condition that metal work function is much higher than that of a p-type semiconductor? Similarly, what if we bring positively charged metal plate in contact with p-type semiconductor, under condition that metal work function is much higher than that of p-type semiconductor? Will valence band electrons from p-type semiconductor transfer to a positively charged metal?

So i understand that two particles are said to be entangled if their joint wavefunction cannot be written as a product of their separate wavefunctions. So [math]\psi(\underline{r}_1, \underline{r}_2) = \psi_1(\underline{r}_1) \psi_2(\underline{r}_2) [/math] is not entangled whereas [math] \psi(\underline{r}_1, \underline{r}_2) = \frac{1}{\sqrt{2}}\Big(\psi_1(\underline{r}_1) \psi_2 (\underline{r}_2) - \psi_2(\underline{r}_2) \psi_1 (\underline{r}_1) \Big) [/math] is entangled. Does this stem from the fact that if two random variables in a joint probability distribution are independent of each other then their respective marginal distributions can also be written as a…

I'm asking members of this society this question although its been almost a year since I last was active...i assure you...what i was getting at has been streamlined and revamped...I am goibg to stop this because i realize i am not following protocol so...

So I am 13 years old and recently discovered Quantum Computing and I think it's the coolest thing ever. But it's really tough to find a good place to start or ease my way into it. I think I could learn and understand it if i could find a place to start. I've heard Classical Physics are what you should learn first but would love to hear your opinions. Thanks in advanced!

Hi, I am an amateur enthusiast and this is a direct question (not a proposal, i'm not nearly qualified to offer a proposal). I would like to throw to experts and people who are more qualified, because it's got me a bit stumped. Could I ask for an answer which is as simple as I am please, lols - answers for dummies style would be just great As I have read it from popular reading books - Copenhagen asks us to believe that the wavefunction breaks down for big things but not for small things until they are observed and offers no explanation as to why, and this is the main criticism of it right? Whereas many worlds says the wavefunction never breaks down and all outc…

I have read in several books and articles that the Copenhagen interpretation is the most common among physicists (latest is a physics textbook from Giancoli). Is that true? If so, why? It requires a boundary between the "quantum world" and the "macroscopic world": when is a system too large and do the wave functions collapse? To me that seems to be adding unnecessary complexity, but I may be missing something. As a side note: a while ago I read about an experiment where they wanted to bring a tiny mirror (i.e. a macroscopic object) in superposition. Does anyone know whether that experiment was ever performed?

i am pretty new in this but qunatum P. it is facinates me. one idea i had is about how sub atomic substances can exist in multiple places at the same time. untill we start to obeserve it. which all others except one to cease to exist. by looking at a subatomic particle we are enforcing the existence of our universe. because of that the others cease to exist. subatomic particles can coexist in multiple universes/paralell... but once we look at it we enforce our universe into it and other parallek universes can not exist here and because of that they cease to exist. like to hear your thoughts on this. i have some more mad theories about light, our origin and so on/..

Hello, I am brand new to the forum and I am wondering what theories there are that use determinism as a posit to explain reverse causality to everyone's satisfaction? Thanks, Dave

Hello, I know I posted a question that was similar to this one a while ago, but this one is very new and claims to have "substantial evidence" that we live in a Hologram. Here is the article claiming to have substantial evidence that we live in a hologram: http://www.southampton.ac.uk/news/2017/01/holographic-universe.page So my main question is: Does this study discussed in this article really prove that we live in Hologram and that we are not real or is it still just a theory. why does it claim to have substantial evidence and is that substantial evidence enough evidence to say that we live in a hologram? Thank you all!

I'm so confused i'm not even sure what i'm confused about, so any help appreciated. So i understand the z-component of the spin state of a particle can represented by [math]|A \rangle = a_1 |\uparrow_z \rangle + a_2|\downarrow_z \rangle [/math], where [math] |\uparrow_z \rangle [/math] and [math] |\downarrow_z \rangle [/math] provide an orthonormal basis in spin space and [math]a_1, a_2 [/math] are complex numbers. I'm also aware that [math]|\uparrow_z \rangle = \frac{1}{\sqrt{2}} |\uparrow_x \rangle - \frac{1}{\sqrt{2}} |\downarrow_x \rangle [/math]. But my understanding of [math]|A \rangle[/math] above is that it only spans a 2-dimensional space defined by the …

It's claimed quantum capacitance depends on material density of states. https://en.wikipedia.org/wiki/Quantum_capacitance ​ Is there a materials or substances which have infinitely high or infinitely low density of states? What is a negative quantum capacitance? Do I understand it correct that high quantum capacitance reduces overall energy which could be stored in a capacitor while negative quantum capacitance increases total energy stored?

Assume Alice and Bob have a set agenda to test for the following case: For a single given electron/positron entangled pair: Alice measures X axes which should be 50:50 up or down Bob measures Y axes which should be 3/4 the same or 1/4 different from Alice Alice measures X axes ...? I've heard form a recorded Richard Feinman lecture, that Alices X spin state can change after Bob measures a different spin state but he never gave any details behind that change. What are the new odds for Alice's X measurement to change? Must it always change? Is it still 50:50 either way? Does it depend on her last result? Does it depend on Bob's last result? Does it b…

There is such a thermoelectric phenomenon: when you will heat one end of a conductor, semimetal or semiconductor, electrons will flow from a hot end to the cold end (like any gas when it expands) and presumably you will get higher density of electron gas on the cold end than it initially was. If some material has 0 Hall coefficient and most likely the same mobility of electrons and holes then electrons and holes will move to the cold end to the same extent and therefore we will likely have larger density of electron-hole gas in comparison to its initial state. If I'm correct in my assumptions and there is such a phenomenon as electron-gas compressibility, is there any li…

Fields are the fundamental principles in QFT but you can start with a Lagrangian who describes a certain model and say "cool, those are the fields that exist physically". But then you can write another Lagrangian, maybe even contain the same fields, which describes the same physics. One of the most radical examples is 1 + 1D bosonization. You start with a theory that contains only fermions and ends with a theory containing only bosons. Totally equivalent to each other. Out of a bosonization is just a 2D trick. And the models of bosonization in more dimensions are punctual models. In 2D you can always do. In extra dimensions depends on the symmetry of the fields and the mo…

Any ideas on how to perform a Casimir Effect experiment using everyday household items? Kindly share ideas here as to how...

I'm looking for papers describing theories of quantum-like neuronal communication models. In particular, I'm interested in the biological entanglement of physical (neuronal) processes and the neurophenomenology of consciousness. Thank you,

The formula itself (f=mvc/h) interpreted by the usual QM that a particle having a mass m and velocity v can be considered as a wave of the frequency f. From here stems the whole concept of "particle-wave duality". But wait a second: the particle by itself can not have a velocity because the velocity is always relative. It has to be another solid physical object the velocity of which is zero (frame of particle accelerator , or target). That means that the formula can be applied to a photon that is produced when the particle hits the frame. Instead of duality we have a coexistence particles and waves

Has someone tested the travel time of particles in the delayed choice experiment? I realize that timing an unobserved object isn't going to be easy, but could we, at least, get an average time?

Entangle two particles, put one deep underground and inside a faraday cage. See what happens when you observe one of them.

http://www.research.ibm.com/quantum/

so if shroedinger cat is a gambler and every time he loses a life terminating device is connected on a 50% chance wouldnt the many worlds school give him a 75% edge? for of 4 worlds he just lives in 3 in which in two he won and in one he lost at roulette

In the double slit experiment you can detect through which slit a photon goes by placing a detector. But the detector prevents interference so the wave behavior is no longer visible. If you place the detector at the beginning of the laser beam, can you then create light that behaves only as a particle? In other words, does the detector changes the behavior of a photon or only how we observe the behavior?

So i'm looking at where the azimuthal quantum numbers come from and have a reached the point where i need to consider Legendre equations/polynomials. I'm a bit pressed for time and i think it will take me quite some time to get my head around this Legendre stuff, so i'm wondering whether i should just take the results on trust and skip the details. The main reason i'm studying quantum physics (other than fun obviously) is to understand vibrational spectroscopy. Any advice?

How did we overlook this? A particle in energy wave form becomes matter with observation.

I'm having a little trouble with some commutational relations between different components of the angular momentum operators. I'm OK up to: [math][\hat{L_x},\hat{L_y}]=\hat{Y}\hat{P_z}\hat{Z}\hat{P_x} - \hat{Z}\hat{P_x}\hat{Y}\hat{P_z} + \hat{Z}\hat{P_y}\hat{X}\hat{P_z} - \hat{X}\hat{P_z}\hat{Z}\hat{P_y}[/math] and the apparently this is equal to [math]\hat{Y}\hat{P_x}(\hat{P_z}\hat{Z} - \hat{Z}\hat{P_z}) + \hat{X}\hat{P_y}(\hat{Z}\hat{P_z} - \hat{P_z}\hat{Z})[/math] I don't understand this 'factoring out' of operators. I thought it was a typo in my notes and the answer is: [math]\hat{Y}\hat{P_z}(\hat{Z}\hat{P_z} - \hat{Z}\hat{P_z}) + \hat{X}\hat{P_y}(…