Decoherence Definition and 179 Threads

In quantum mechanics, POVMs can be considered more fundamental than PVMs because PVMs can be considered a special sort of POVM. However, because of the Naimark extension, one can formally consider POVMs to always be derived from PVMs. Accordingly, one could argue that choosing PVMs or POVMs to...

Hi, I was wondering whether we are sure (I know, strong word) that decoherence is the mechanism that takes us from the quantum world to our classical world. Correct me if I'm wrong, but basically decoherence is a phenomenon where we have a bunch of quantum states that, when piled onto each...

I have a couple of questions about entanglement and decoherence! 1. Sometimes you read that, strictly speaking, all electrons are entangled with one another. But can that be right?! Isn't it at least the case that electrons have to have interacted with one another in the past in order to...

I read it some where that there is very small decoherence for photons. The reason being that photons do not interact with each other (Is that because photons are chargeless, colorless and flavourless particles?) and hence the information that they contain tends to stay with them. They have a...

Decoherence relationship to the "measurement problem" I have heard the argument that "decoherence" in quantum states causes the quantum collapse to occur, and that this solves the "measurement problem". But I'm still left with a nagging question... Does decoherence only produce quantum collapse...

1. What (property) makes a photon less likely to decohere/(entangle with the environment) relative to other "fundamental" particles (non leptons?) such as an electron?...say during single particle interference experiment Photon single particle interference can done without the need for a...

It seems that many systems currently studied, are very fragile to dechorence. Great care is taken to isolate them from even the smallest amount of interatction with the outside environment. Yet, the most well known quantum mechanics experiment, the double slit experiment, seems incredibly...

While reading Zurek paper Decoherence and the transition from quantum to classical -- REVISITED, he makes the statement: What exactly is a "robust enough" correlation (from a interaction with the environment)?

I found an interesting paper here a two level system is measured by a harmonic oscillator(the apparatus). the apparatus is coupled to its environment, a bath of oscillators. The article shows how the reduced matrix of S+ A decoheres (the off diagonal elements tend to zero). I am looking for a...

Books of quantum mechanics are very ambigous in this aspect. A classical apparatus that collapse wavefunction of a quantum system must "quasieliminate" the non-diagonal elements of density matrix, or have a quasiclassical wavefunction of the form ae^{iS\hbar^{-1}} where a is a real slowly...

Yeah, the beta movement from pshycology for example, it impose that a perceptions matter in a 0,1 s (+ or -), but this need a physical explanation. The decoherence times for examle cat alive cat dead is very low than this. But we are there while decoherence. Why we don´t perceive it. The...

¿Can´t matter that decoherence matters for 2 distinct observables simultaneously ¿ Maybe the measurement apparatus must been defined clasically in this case

¿ What´s the matter if after decoherence the measured system coherences again with the bath ¿ Is measure erased

I know that the theoretical decoherence mechanism makes the density mattrix diagonal, but my question is if that happens in real life. I mean, let's take the hidrogen atom (lets work in the QM framework And not in the QFT framework in order to have multiple stationary states) And suppose that...

I was recently told virtual particles don't cause decoherence. Why not? Do they just never interact with their environment (apart from transferring energy/force) so they can never collapse a wavefunction?

does quantum decoherence mean object is leaking into the environment and actually exists permentely as a superstion of states?

As the Title describes, Is the measuremet problem completely solved by the decoherence Program? In specific I would like the following question addressed. Is there is clear explanation as to what it means to Record Infromation? Can it explain the behaviour of a photographic plate? What happens...

what is the formula for estimate decoherence time and decoherence length from voltage, current and resistivity value ?

From what I have read online, decoherence is an irreversible process that gives the appearance of wave function collapse. For example, a macroscopic measuring device will always interact with the particle it is trying to measure, and the particle becomes entangled to this environment, and...

Is the interaction with the Higgs field helping/causing the process of decoherence?

"The characteristic feature of the first (often called ‘dynamical’ or ‘environmental’ decoherence) is the study of concrete models of (spontaneous) interactions between a system and its environment that lead to suppression of interference effects"...

In principle, what is the absolute simplest arrangement to cause decoherence? In other words what constitutes a measurement? Clearly gravitational interaction is not sufficient.

Hi everybody, which are the physical laws that make photons free from decoherence? I only read about the fact that photons have no charge, but why this implies no decoherence? Thanks you all, gioia

Hi everybody, I've searched all the internet but I can't find the answer to my question. Which are times of decoherence for different physical realization of a qubit? Like, if I use photons, or spin electron, or nuclei, or ion trap, to encode a qubit, which are times of decoherence for each...

Hi all, I've been reading the seminal Zurek papers on decoherence but there is one (crucial) point on which I am confused. I understand the mathematical demonstrations that over very short timescales the superpositions of states represented as off-diagonal terms in the density matrix can be...

Hi all, My limited knowledge of quantum decoherence leads me to believe that it can be demonstrated experimentally via rather humble apparatus involving low power lightbulbs, a few sensors, & some plywood with holes in & some switches etc. I was just wondering what kind of pattern you get if...

By 'Genuine Decoherence' - I mean collapse of the wave function by a theory and its mathematical equations. If a micro system encounters a macroscopic apparatus - in collapse theories a definite state appears for both the apparatus and system, but after a tiny time since the system entangled...

Two questions regarding decoherence 1) preferred pointer basis: Decoherence explains why a quantum object interacting with a measurement device plus environemt results in a "classical state" of the measurement device. What is the explanation for a "preferred pointer basis"and why does the...

I've read the Quantum Zeno (QZ) Effect is caused by Quantum Decoherence (QD), and that QD is, in general, a representation of the wave-function collapse of a quantum system (the Wikipedia explanation on this is confusing to me, to say the least). If I understand the QZ Effect correctly...

I'm trying to at least understand what decoherence can and cannot explain about how quantum mechanics works, the more I read, the less clear I am about what is known and what is merely speculative. So I finally decided the only way to get any further was to try and clarify what I think is...

Why doesn't it occur constantly and only when 'interacting" with another larger scale phase space? Why does an electron for example require a large scale human readable detector in the way to interact that way with the environment when the environment is there anyway? Air, Dust, etc. -- Also...

I'm a physicist, but I'm not a specialist in the foundations of quantum mechanics. This month's Scientific American has an article by Vlatko Vedral about entanglement and decoherence. Paywalled article, with a brief summary...

Hi, I'm confused by subtle differences between the concept. Let's take the example of a Schrodinger Cat. Supposed you could make a box that can isolate anything inside from say gravity, microwave radiation, is in 0 kelvin, etc. or let's just accept (for sake of discussion) that a box can totally...

In order for decoherence to work, does it require the second law of thermodynamics to be valid?

I've been reading a bit about quantum decoherence today. But I'm stuck on the following contradictions: I think I've read somewhere that after the wave function collapses, it will resume its normal superpositioned state soon after measurement. But according to quantum decoherence a...

Von Neumann wrote in a major physics book decades ago that consciousness was what collapse the wave function.. how could he stated this bizaare statement and the facts remain up to this day? Is the interpretation been refuted already by the latest discovery of Decoherence? I can't find...

Just read a bit about decoherence from wiki, it seems to me that according to this interpretation, the probabilistic nature of QM is no different from statistical mechanics, and the irreversibility of measurement is just thermodynamic, so does this mean decoherence is indeed a deterministic...

Suppose 10,000 years from now, we perform the ultimate macroscopic superposition experiment: We're somehow able to prepare an entire star, complete with a large orbiting planet, as a pure quantum state. It is surrounded by a black shell, of radius 1 light-day, which is maintained at a...

"Decoherence does not generate actual wave function collapse. It only provides an explanation for the appearance of wavefunction collapse. The quantum nature of the system is simply "leaked" into the environment" http://en.wikipedia.org/wiki/Quantum_decoherence I have taken a full year of...

Hello, I would like to ask if there is a standard explanation of decoherence in the universe as a whole. I can see how decoherence is responsible for the classical behavior of a measured macroscopic object in its environment. But what about the big picture? Is it thought that the entire...

From my understanding decoherence occurs whenever a quantum object interacts with a macroscopic sized object. So for instance a measurement involving a photographic plate registering a particle will cause decoherence of the wavefunction, which appears to us as the wavefunction collapsing...

It seems decoherence can not explain the measurement problem, but I wonder why I rarely read about the interaction between a quantum system and the environment being causal as an interpretation. What about a causal interpretation for the process of decoherence? This avoids a true collapse...

Why does decoherence not fully solve the measurement problem? I know that must have been discussed here before a lot, maybe someone can me direct to a earlier thread or post that explains it well? I read some QM texts, but they mostly do not discuss decoherence. I know something with...

Hi, I keep confusing myself between decoherence and the transition from pure to mixed, both of which, as far as I know, come about due to the interaction of a system with the environment. I like to think about things in terms of the density matrix to get it solid in my head. Can someone...

What is the relationship between decoherence and entanglement? Does the decoherence destroy entanglement of system and environment?

Is decoherence a resolution to the issue of measurement? I have read arguments on both sides.

Please describe decoherence simply to someone with a mostly complete undergraduate understanding of quantum mechanics.

In statistical physics, we have a system interacting with a (random) medium. This is what shifts and broadens the system states and this is well understood. Clearly the random interaction is responsible for the shift and broadening(because if it were nonrandom, it would simply cause a...

Can the Quantum Zeno Effect be solely attributed to decoherence? In every single case? Is the consensus on this matter opinion, or rigorously tested fact in which every case can be attributed to decoherence? On a more well known note, can the supposed wavefunction collapse (which gives...

While I understand that the a single quantum can indeed exist in a superposition, does the interaction of various quanta exist in superpositions as well? If so, is the idea of a limit on the number of these interactions before a definite state is reached what is referred to as decoherence, and...