Quantum information Definition and 104 Threads

Last year I've finished the undergraduate course in Mathematical-Physics and Mathematics and this year I've started on graduate school on Physics in order to obtain a master's degree. What I'm really interested are two main topics: general relativity and quantum field theory. I also like...

Hey all! I'm a junior undergrad and am beginning to think about what graduate programs I would like to apply to next fall. Recently I've been doing theoretical research in quantum computing which I'm really enjoying. I'm pretty sure that this is the sort of research I would like to pursue in...

An interesting paper has appeared on nature.com: http://www.nature.com/articles/srep32815 The abstract: I expect this to spawn plenty of pop science claims about "scientists say we can reverse entropy". But the paper itself looks like a good discussion of how the second law actually works...

I am an undergraduate student in India doing my final year BS degree in Math. I am extremely interested in quantum mechanics and want to peruse quantum computation. What is the best possible course that I can take for my Masters? There appears to be a limited number of colleges that offer a...

How is information conserved when one form of energy is converted to other? Like how a black hole's gravitational energy is used to create photon pairs near the event horizon, what happens to the information in the gravitational wavepackets (gravitons?) and how is it not lost?

Homework Statement Prove the following relation for ##\zeta:=r e^{i \theta}##: S(\zeta)^\dagger a S(\zeta)= a \cosh r - a^\dagger e^{i \theta} \sinh r with ##S(\zeta)=e^{1/2[\zeta^\ast a^2-\zeta(a^\dagger)^2]}## and ##a## being the annihilation operator with eigenvalue ##\alpha##...

I have just finished my 2nd year of undergraduate study, which had the first pass of QM in it. I want to do a PhD in Quantum information/computing. What can I learn in my own time to get me closer to understanding QM information/computing? Currently I only know what we covered in lectures, and...

Homework Statement Prove the following relations (for ##\zeta:=r e^{i\theta}##): \begin{align} D(\alpha)^\dagger a D(\alpha)&=a+\alpha\\ S(\zeta)^\dagger a S(\zeta)&= a \cosh r- a^ \dagger e^{i\theta} \sinh r \end{align} Homework Equations ##|\alpha\rangle## is the coherent state. ##a## and...

Hi everyone, Hoping someone can give me insight on this. I am visiting two schools next week - CU Boulder and University of Maryland, both of which I have been accepted to for quantum information experiment (PhD.) Both are very highly ranked and seem to have great departments, and I'm...

Hi everyone I need help understanding the lines on the attached picture. In the proof of corollary 14 how does it follow from corollary 13 that: Λ(X) = ∑li><il Tr[KijXKij†] I think what has been done is take a partial trace over the system HB, but what exactly is the effect of this? It says...

Hi, guys, I am an undergraduate pursuing electronics and communication in her 3rd year. For last few months, I have been trying to obtain internships in the field of quantum information so that I could have more exposure to it. I am already pursuing the subject learning it in bits by bits and...

Consider a system with countable quantum states. One can define Jij as the rate of transition of probability from i-th to j-th quantum state. In H-theorem, if one assumes both $$ H:=\Sigma_{i} p_{i}log(p_{i})$$ $$J_{ij}=J_{ji}$$ then they can prove the H always decrease. The latter is Fermi's...

I would appreciate any clarification (or opinion) on the relationship between Quantum Numbers and Quantum Information. My question is related to the puzzle wether matter merely represents information or - at the basement level of reality - actually can be said to be information. Just to give...

Does anyone know anything about quantum information theory? I am reading a text about transmitting quantum states, represented by density matrices, through channels. Here the depolarising channel is defined as the map: X: -> (1-p)X + pτ Tr[X] which with probability (1-p) maps the state onto...

Hi everyone. I'm just looking for schematics of cnot quantum gate, but on the Internet it only talks about it from a mathematical point of view. I want to ask you if you have some drawing, or schematics of it, from a "Physical" implementation, in the sense, how are the spins prepared, how we...

I am a rising senior at a small liberal arts college, with an incredibly small (and therefore unrecognized) physics program. I am seeking advice regarding which Ph.D programs are within my reach. I plan on applying to AMO (Atomic, Molecular, and Optics) Ph.D programs with the intention of...

Hello everybody, This first post is intended, as requested, as a small self presentation. I'm an italian electronic engineer, a programmer for job and a passionate in Quantum Physics and Physics (and Mathematics) in general. I live and work in Padua. I've almost finished to follow a series of...

For a system consisting of multiple components, say, a spin chain consisting ofN≥3spins, people sometimes use the so-called geometric measure of entanglement. It is related to the inner product between the wave function and a simple tensor product wave function. But it seems that none used this...

I am still in high school but my curiosity is not stopping me from posting in this forum. How is data stored in SSD? How does it differ from the old HDD? I heard that atoms are used to store data. How? Binary consists of 0 and 1. How does someone use an atom to represent 0 and 1? Does positive...

Good day, I'm starting my master in physics, and it's time for me to choose my courses. I've decided that I probably want to pursue the direction of quantum information processing, and I'm trying to pick my courses with that in mind. For my first semester I'll be taking four courses: Quantum...

Hi everyone, Recently I read an introduction to quantum information and got interested to begin a research work on it. I am now reading Neilsen's Quantum Computation and Quantum Information. There are a lot of things but I don't know how I can find a suitable issue and start writing an article...

Could someone provide me with simple answers to the following questions? I have tried to find the answers on the internet but most search results are beyond my comprehension. 1. What is the maximum number of qubits that a photon can carry? 2. If Alice packs a qubit in a photon and sends...

Is there a thread on this forum that discusses this paper? http://arxiv.org/pdf/quant-ph/0205039v1.pdf It would suggest that the quantum wavefunction is a representation of our state of knowledge of a system. Is this an accepted view?

Hi guys, I've been reading a paper recently about trapping pseudo molecules in a magnetic field gradient. It says at one point that one of the successes has been due to using microwaves opposed to lasers; they claim that the reason for this is because lasers are notoriously difficult for...

A big hello to all physicist, chemist, engineers and anybody reading this thread, Back in the old days, information that used to be transmitted was analogue. Later it became numerical improving immunity vs noise; However I read a couple of days ago articles about the possibility of...

I am a little confused at the description of quantum information, even though I more or less understand the concept of a qubit as being a superposition. That which confused me was a phrase saying that the quantum information is the classical information that can be retrieved. But one can only...

I'm skeptical of something Neil Turok said, having to do with quantum information. http://thetyee.ca/Books/2012/10/13/Neil-Turok-Universe-Within/ From what I understand, a qubit can store an infinite amount of information. So, where does he get the number 300 from? Why not just one? Also...

Hi everyone, I'm looking to go to graduate school for a Master's in scientific computing or computational science but want to go back for a PhD in physics. I'm just starting to look into quantum information theory and while I find plenty of PDF files and articles about the topic I can't find...

I will finish my Master studies in theoretical physics next year, and I want to do a PHD in Quantum Information (my main interest). I want to apply to universities in the UK and Germany (right now I restrict myself to these two countries). What are the universities you know of, that have Quantum...

Why is |<{\phi}|exp(i{\alpha}|{\psi}>|^2 for any alpha not dependent on choice of alpha, but |<phi | exp(i\alpha) \psi >|^2 is dependent on choice of alpha. Also, is there a list somewhere for how to type this garbage on physics forums; I'm used to using TeX maker for writing math, but I always...

Hi! As I understand it, Quantum Information Theory is an attempt to apply the Classical Information Theory (i.e 0's and 1's) into the Quantum realm of superpositions. I recently came across a fascinating interpretation of QIT wherein it was described as possibly the law that effectively...

Hi, I am a student in Europe. I have been reading through the posts on Graduate schools and the essays like the one by Zapper on how to become a physicist. I am now in the stage of searching for a PhD position. 1. I would like to know what you guys think about the scope of Quantum...

Hello, i want to know if there is any way we can describe the way our brain transfers information using Quantum Information theory. I have been looking at Quantum Information theory for some time now and would want to know if it will ever be possible to transfer information directly from the...

I seem to be at a loss to understand something pertaining to the role of the phase factors in defining quantum states and their consequences in quantum computing. So, I learned in class and read in numerous books, and online, that the phase factor has no physical significance as it does not...

I'm a graduate student, and now in the second year at graduate school I'm going to have to work on a research project on some field. I want to specialize in theoretical quantum information. My main motivation is that this field studies, in fact, quantum mechanics and is actually building and...

Anybody have suggestions on any reading material that would be (sorta) accessible to an undergrad? Intro stuff, anything would be great. THANKS!

What is the best place to do a PhD in quantum information? I want to do research on quantum entanglement and quantum teleportation.

Hi everybody, I ve been thinking a lot lately about the thesis I am supposed to start next year. I will study the categoric formulation for quantum mechanics, polytope correlations and links with the complexity theory (post quantum models etc). But on the other hand, I find my courses on...

hello,i had posted in this forum a question about linar algebra and quantum mechanics because i am studying quantum computation and information, i have the following book:"quantum computation and quantum information" by Michael A.Nielsen and Isaac L.Chuang. and i think it covers most topics of...

Hi. I'm an undergrad majoring in maths/physics from a US university now taking a year abroad at university of Bristol (UOB) in UK. After this academic year, I'll go back to study in my home university for a year and then graduate. The quantum information (QI) researches at the department of...

Note: This is a revised re-post of an earlier thread that I started, but I feel there was some misunderstanding in it's purpose so I have attempted to clarify with the current revisions. This is not intended to be a thread on metaphysical speculation, but rather an observation on a property of...

I'm trying to find grad schools to apply to, and I'm particularly interested in universities with strong programs in quantum information science/quantum optics/quantum computing (what each university calls it seems to change depending on who's funding it). I haven't gotten my physics subject...

I'm an undergraduate physics student and I'm looking for a MSc program at a european university (taught in English), related to quantum information, quantum optics etc. Any opinions?

Hey folks, I have a pretty simple quantum information question that I was hoping somebody could answer. let's say I have a pure state \ket{\psi} = \alpha \ket{10} + \beta \ket{11} + \gamma \ket{01} + \theta \ket{00}. I then perform a measurement on only the first qubit and observe a...

Homework Statement We have two people, Alice and Bob. They get numbers random, but we have two cases. Firs case: \sum6 If: Bob get 6 then Alice get 0 Bob get 5 then Alice get 1 Bob get 4 then Alice get 2 Bob get 3 then Alice get 3 Bob get 2 then Alice get 4 Second case \sum4 If...

And: So they have used phase information to control a biological process, but how about the organisms themselves: do they use light in the same way? They also mention 'the vision response', is that our eyes? Do our eyes/brain use phase information to create our vision?

Hello. I've got childish question. I know that quantum computers are more effective than classical ones in solving some problems. Naturally, a thought have come to me: are there computers which are more effective than quantum ones, maybe some "Superstring" computers? And maybe there are...

is there jobs on quantum information?? does anyone know the career potential for someone who takes phd on quantum information? i mean a kind of job other than research assisstant in university?

Hey all, I'm a beginner of the Quantum Computation and Quantum Information. For a long time, I feel very confuse about the question bellow. Could you do me a favor and show me the proof? Many thanks! Question: Show that any qubit can be expressed as psi=exp(iγ)[cos(θ/2)0+exp(iΦ)sin(θ/2)1]...

Hello, In my university there is a bit of a fuss about Quantum Information (QI). A few professors work in this field and there have been some conferences where they try to explain to the rest what is QI and so on. I think it is safe to say I know a bit of quantum mechanics, not at a...