Quantum decoherence is the *irreversible loss of ordering of the phase angles* between the components of a system in a quantum superposition resulting in classical or probabilistically additive behavior, thereby suppressing interference of wavefunction components.

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Decoherence Free Subspaces and how they stay this way, using the Zeno Effect

I am currently reading papers discussing the Zeno Effect, which discuss how measuring a system at high frequencies can almost freeze the state of a system, or keep the system in a specific subspace of ...
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Quantum fluctuations in a classical domain?

"In the presence of chaos, even small fluctuations (including quantum fluctuations) can be amplified to produce large uncertainties in later behavior"(http://arxiv.org/pdf/gr-qc/9210010v2.pdf) Is there ...
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Modelling the onset of decoherence in a subspace as a transition out of the subspace

http://arxiv.org/pdf/0903.3297v1.pdf I am currently reading papers discussing the Zeno Effect. The linked paper discusses modelling a transition out of a wanted subspace as the onset of decoherence. ...
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Probabilities with the Density Matrix

The density matrix of the system is given by: $$ [\rho_{S}(t)]_{mn} = [\rho_{S}(0)]_{mn} e^{-i\omega_{0}(m - n)t} e^{-i \delta(t)(m^2 - n^2) - \gamma(t)(m - n)^2}, ...
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Decoherence, collpse, and WHEN does the collapse occur?

The idea that decoherence stands behind the so-called collapse (reduction) of the wave-function doesn't seem satisfactory. Consider a quantum particle whose wave-function is of the form (1) $$\left|...
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Decoherence and interpretations

With quantum decoherence, are there still any "gaps" in our knowledge of quantum mechanics that hint (either in terms of the physics, philosophy, or otherwise) at the need for further interpretation? ...
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What are the requirements on conditional unitaries for overcomplete bases?

On way to describe "pure" decoherence (that is, decoherence with respect to a basis that doesn't involve transitions between basis states) between a system $\mathcal{S}$ and an environment $\mathcal{E}...
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Does quantum mechanics require classical measurement apparatus?

I am trying to learn quantum mechanics and I have a question. Landau, in his quantum mechanics book says that it is in principle impossible to formulate basic concepts of quantum mechanics without ...
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What is the influence of QED vacuum in electron-double-slit experiments?

In a recent question on superpositions of different quarks it was explained, that the superpositions of different electric charged particles cannot exist, in contrast to strangeness quantum number. It ...
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Schrödinger's cat experiment in the context of decoherence

I am trying to visualize in more detail the Schrödinger's cat experiment in the context of decoherence. Please let me know if the description below makes sense or is somehow flawed. If the ...
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How does gravity affect entanglement?

Hypothetically an entangled pair of atoms are placed inside two similar satellites orbiting at the same altitude, one of the satellite will then slow its speed and descend towards the surface of Earth....
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Coherences in the density matrix

It is said that the off-diagonal elements of density matrix are coherence. When a system interacts with its environment the off-diagonal elements decay and the ...
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How can the pre-measurement be fulfilled?

In the decoherence program, the pre-measurement refers to the evolution in which the system and apparatus form a Schmidt state. In Maximilian Schlosshauer's review article(2005), I read "the linearity ...
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Decoherence: What is the spectral density of a bath of gaseous particles?

I am studying the decoherence theory of a two-level system in interaction with a background gas. Caldira and Leggett (1987) showed that any environment can be modeled by a bath of harmonic oscillators....
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Finding the dependence of dephasing time on flux noise in Transmon Qubits

Before introducing some relevant concepts I'll begin by stating my question. What I am looking for is the connection between the noise the flux through the SQUID in my transmon qubit (related to the ...
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Continuous spectra and quantum decoherence

Suppose that some quantum wave function $\psi = \int a_i \,i\rangle \,\,di$ where pseudo-spanning ket "vectors" of $\psi$, $i \rangle$, are continuous. (thus the use of integral.) By normalization, $...
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decoherency of number states

The meaning of decoherency is: When a nonclassical state, transitions to a classical state. It means that the state lost it's phase information. I can't understand how it happens in number states.
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fast quantum random number generator + limited decoherence rate => Schrödinger cat state?

Suppose that fast quantum random number generator (QRNG, https://qrng.physik.hu-berlin.de/) is placed in a subsystem which has limited interaction with the rest of the world. What would happen if ...
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Dissipation vs dephasing in master equation

I have a two-dimensional system, with Hamiltonian $H_s=ωσ_x$ which is interacted with the environment through $σ_z$. The decoherence process is described by a master equation like: $$∂ρ/∂t= −iω[σ_x,ρ]...
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Proof of Tridecompositional Uniqueness Theorem (Elby and Bub, 1994)

I'm looking for a proof of the Tridecompositional Uniqueness Theorem (Elby and Bub, 1994). Could someone help me? References: Maximilian Schlosshauer, arXiv:quant-ph/0312059; p.12-13. A. Elby &...
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The Hamiltonian of the Spin-Boson Model

I came across the following two specifications of the spin boson model with weak system-environment coupling: Dissipative/Population Decay Model: $$ \mathcal{H} = \frac{\omega_{0}}{2}\sigma_{z} + ...
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How is the lifetime of a symmetric and antisymmetric state determined by its constituents

In the context of quantum mechanics, there is the concept of so called symmetric and antisymmetric states, which can have multiple constituents. A type of hybridized state, if you will. To keep the ...
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Can particles recohere after measurement?

I try to elaborate the relation between decoherence and the ouputs problem. Talking about the Stern-Gerlach experiment Caldeira writes here: "Recovery of coherence should be achieved simply by ...
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Resources on estimation of environment model for environemnt induced quantum decoherence

I am curious to see what literature exists about estimation of a quasi-classical environment interacting with a quantum system causing decoherence in system states. There has been in general a lot ...
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Data: decoherence time

Searching for experimental data on decoherence time. For example, this type of data can look like (but is not limited to): atomic species (eg. Carbon) vs. decoherence time. Physics stackexchange ...
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Collisional decoherence and trajectories

The density matrix of a mesoscopic particle subjected to collisional decoherence satisfies the equation $$ i\frac{\partial \rho(x,x',t)}{\partial t}= \frac{1}{2m}\left (\frac{\partial^2}{\partial x'^...
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Decoherence in the long time limit of density matrix elements

For a state $$ |\Psi(t)\rangle = \sum_{k}c_k e^{-iE_kt/\hbar}|E_k\rangle, $$ the density matrix elements in the energy basis are $$ \rho_{ab}(t) = c_a c^*_be^{-it(E_a -E_b)/\hbar} $$ How is it that ...
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Why decoherence?

Why do we study decoherence? I mean the postulates of quantum mechanics agree with experiments perfectly and we all know how a superposition state looks like, for example the spin-z up state is ...
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Derivation of the dynamical master equation for collisional decoherence of a massive particle

I'm working on the problem of collisional decoherence of a massive particle interacting with an environment of light particles. The problem. I have some confusion regarding the derivation of the ...
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Why is it necessary for all the component-states to have same phase for interference?

I am currently reading Decoherence. In this site, it is written : Now here is the absolutely key point: every component eigenstate has an associated phase . It is this phase$^1$ which gives the ...
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Non-unqiue basis sets of reduced density matrix in quantum mechanics/decoherence

In Why decoherence solves the measurement problem by Art Hobson: $|\psi \rangle _{SA} = c_1|s_1 \rangle |a_1 \rangle + c_2 |s_2\rangle |a_2 \rangle$ which is a wavefunction that describes non-local ...