Quantum entanglement is the mechanism by which quantum correlations between two sub-systems survive even after being physically separated from an interaction region. The correlations could in principle survive without neither time nor space constraint.

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Non-locality and topology

This is a purely speculative question: Has there been any work that describes non-locality/entanglement in QM by using exotic topologies in configuration space? The 'conceptual' picture that I have ...
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Is this state an example of a separable state or an example of an entangled state?

The Hong–Ou–Mandel effect also underlies the basic entangling mechanism in linear optical quantum computing (https://en.wikipedia.org/wiki/Quantum_computing), and the two-photon quantum state |0,2> + ...
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Is linear polarization of entangle photons in 2-particle decay always correlated?

In Aspect's paper "Bell's Theorem: The naive..." and in an 2002 AJP article by Dehlinger and Mitchell "Entangled photon apparatus..." the photons are described to be in the $|xx\rangle+|yy\rangle$ ...
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Under what conditions does a beam splitter entangle two input photons?

There is a dispute on PhysicsForums related to what are the conditions necessary for two photons to be entangled by a beam splitter. Lots of references given by the forum users but they never arrive ...
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Does a normal torch emit entangled photons?

I was reading a sciencenews.org post about three photons being entangled. My question here is, why is the chance of producing an entangled pair once in a billion times? Isn't every particle produced ...
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Entanglement in Quantum field theory [duplicate]

How is entanglement represented in a field theory? For instance how can I represent a maximally entangled state such as a Bell state? Would such an approach also apply in a Conformal field theory ...
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21 views

Production of entangled photons by spontaneous down conversion [on hold]

I have found that the conditional uncertainty product of position and momentum of any one photon produced in the spontaneous parametric down conversion process using a gaussian pump beam decreases ...
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1answer
26 views

How is conversion inside heat engines of heat (random motion) to work (organized motion) explained in quantum physics?

When heat engines convert heat into work, they change the random motion of millions of particles into motion in a single direction. What is the phenomenon responsible for this alignment of ...
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140 views

Quantum probability of entangled spin-1/2 particles?

Let us say that you have two entangled spin-1/2 particles (entangled in such a away that angular momentum is conserved). Let us say particle 1 moves to the left and particle 2 to the right. We measure ...
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Couder-Fort Oil Bath Experiments and Quantum Entanglement Phenomena

The oil bath experiments of Couder and Fort have been able to reproduce various "pilot wave like" quantum behavior on a macroscopic scale. Particularly striking is the fact that the double-slit ...
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How do particles entangle and how does polarization work? [closed]

I am trying to learn about how particles get entangled and when I searched it up I did not understand how polarization worked. I am still in elementary school so if please make the definition simple! ...
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Entanglement of kinetic energy [closed]

Mass-energy is conserved in particle events. Consider a scattering event where a certain amount of kinetic energy is conserved between two emitted particles. However the velocities (and thus the ...
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3 particle spin entanglement [closed]

When 2 particles are emitted with equal and opposite spin a measurement of one particle's spin orientation fixes the spin of the other particle in the opposite orientation so as to conserve the total ...
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27 views

Possible with entangled particles? [closed]

I saw this video on Veritasium, where it is shown that a electron's spin direction can be changed using radiowaves. Would this be possible if that electron was entangled with another electron? Is it ...
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43 views

Bell state Orthogonality [closed]

Given the Bell states $|\Psi^+\rangle = \frac{1}{\sqrt{2}}(|H\rangle_1|V\rangle_2-|V\rangle_1|H\rangle_2)$ and $|\Phi^-\rangle = \frac{1}{\sqrt{2}}(|H\rangle_1|H\rangle_2-|V\rangle_1|V\rangle_2)$, I ...
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28 views

Is quantum entanglement feasible for communication? [duplicate]

Is it possible to have two entangled particles, say electrons, and transmit information through a property, like spin? I was recently watching a video on how qubits work. In the video a group of ...
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Can different components of a wavefunction become entangled with different systems?

Imagine a $z$-basis spin Stern Gerlach experiment where a single particle is put through the apparatus. The output is a spin state vector consisting of the sum of the two $z$-spin states. Each spin ...
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quantum entanglement and its application in migratory birds [closed]

Explain the concept of quantum entanglement.Also explain its application in migratory birds. i know that it also has a relation with the magnetic field of the earth.
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What is coherence in quantum mechanics?

What are coherence and quantum entanglement? Does it mean that two particles are the same? I read this in a book called Physics of the Impossible by Michio Kaku. He says that two particles behave in ...
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49 views

Quantum non-locality with commuting measurements?

We consider the Bell scenario, in which Alice and Bob share an entangled pure quantum state $\mid \Psi \rangle_{AB}$. Alice gets an input in the set $\{1,2\ldots X\}$ and Bob gets an input in the set ...
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Demonstrating quantum non-locality by two consecutive measurements

Entangled state measurements says that Bob's measurement polarizes the Alice's observations. Bell has invented that we need a third property (axis) of measurement is needed in order to demonstrate ...
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Existence of anything below event horizon of a black hole

I have recently listened to L. Susskind's lecture on youtube and could not quite get some it's points. As far as I understand the argument is as follows. Suppose we have region A inside event horizon ...
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4answers
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How do particles become entangled?

A person asked me this and I'm just a lowly physical chemist. I used a classical analogy (how good or bad is this and how to fix?) Basically, light has a net angular momentum of zero, insofar as ...
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Entanglement, Bohr-Einstein Debate, Bell's Inequality

On BBC episode The Secrets of Quantum Physics (Part 1) Jim Al-Khalili explains quantum mechanics for the layman. In the first half, he does a very good job; in the second half, either he thought his ...
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What are the phenomena responsible for irreversible increase in entropy?

https://www.quantamagazine.org/20140416-times-arrow-traced-to-quantum-source This article says that entanglement drives the arrow of time of increasing entropy towards thermodynamic equilibrium: ...
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Is quantum entanglement related to the thermodynamic equilibrium?

https://www.quantamagazine.org/20140416-times-arrow-traced-to-quantum-source "Today, Lloyd, Popescu and others in their field see the arrow of time differently. In their view, information ...
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When does the world split in MWI

I've been reading Eliezer Yudkowsky's blog post regarding decoherence and many worlds, and although he is not a physics but a strong proponent of MWI, I can basically see why he feels that MWI is a ...
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Precedence and quantum entanglement: The Alain Aspect experiment in spacetime

Recall that the spin components of a spin-entangled pair do not exist until one of the pair undergoes quantum observation, at which time both of the pair immediately obtain quantum random opposing ...
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If all the particles of a Bose-Einstein condensate become entangled with each other,does the system still remain a Bose-Einstein condensate?

I know that an entangled system is found in a single entangled state and that when you try to observe the individual state of a particle from an entangled system using a reduced density matrix, you ...
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The big bang singularity and entanglement [duplicate]

Since our universe began as a singularity would that mean that everything in the universe is entangled with itself? I am not sure that makes sense, but hopefully some one can figure out what I am ...
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61 views

If I pass one member of an entangled pair through a polarizer, does the other member assume a correlated polarization?

Does that mean I have influenced the measurement result of one member of the entangled pair by acting on the other? Can information be sent this way using entanglement?
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66 views

Replica trick for calculating Entanglement Entropy?

This is probably a simple question. Von Neumann entropy is defined to be $$S_A=-tr_A\rho_A \log\rho_A$$. And it's said that it can be calculate from the "Replica trick": $$S_A=\lim_{n\to 1}\frac{tr_A ...
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Would a collection of entangled particles behave like a superfluid? [closed]

Superfluidity of a Bose-Einstein condensate comes from the fact that all the particles are found in the same quantum state. They are described by the same macroscopic wavefunction. They never collide ...
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Why doesn't time dilation resolve entanglement

I'm a layperson who has read bits about relativity and quantum mechanics over the years, so this is a naive question, but I can't see where My reasoning fails... Photons travel at the speed of light, ...
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Is the following experiment about quantum swapping possible?

Alice has two pairs of entangled particles: A-B and C-D. Alice sends A and D to Bob. The particles arrive at 1 pm. At 2 pm, Alice flips a coin and if it's head, she uses entanglement swapping to ...
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Quantum Erasure Spookiness

First off - I am not an expert. I am intrigued by quantum physics and have a layman's understanding at best. I've looked at other questions, but either the answers are not answering my question, or ...
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Can quantum entanglement be a proof of a 4th spatial dimension?

What I know about quantum entanglement is almost nothing. What I know can be resumed to: "two particles created together have a correlated behaviour no matter the distance between them". This is ...
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On $k$-extendability of bipartite states

Definition of $k$-extendability can be given as follows. Let $k\in \mathbb{N}$. A state $\rho_{AB}$ on a bipartite Hilbert space $\mathrm{A}\otimes\mathrm{B}$ is $k$-extendible with respect to ...
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Basic Quantum Entanglement

Quantum entanglement means that multiple particles are linked together in a way such that the measurement of one particle's quantum state determines the possible quantum states of the other particles. ...
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What are the current obstacles to experimentally testing quantum pseudo telepathy?

Quantum pseudo-telepathy refers to how, in some specific coordination games, isolated players can do better when they have pre-shared some entangled qubits. I understand how it works in theory and ...
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Will efficiency of SPDC to create entangled photon increase with resonance?

If I put a non linear crystal inside a resonant cavity will efficiency of SPDC process to create entangled photon pair increase? If so by how much? Is there any experimental data? I have this paper ...
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Entanglement using a beam splitter?

Can someone explain why splitting light using a beam splitter is an example of entanglement? I get the part where we cannot definitively tell which photos have gone in which direction, but i thought ...
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Questions regarding reversible processes, entanglement, and time reversal symmetry [closed]

Can we, a priori, state that a physical state is entangled with its environment? Its hard for me to come up with a reason for why we can't. For my next question, consider a physical state: ...
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Pauli exclusion principle and Entangled pairs

It is true for fermions in the same potential that the total wavefunction of two particles must be antisymmetric with respect to exchange of electrons. Which means the spin wavefunction is given by ...
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Can decoherence occur just by simple reflection?

I create an entangled photon pair. One photon is sent inside a resonant cavity which reflects the photon many number of times. Will there be decoherence between photon in the resonant cavity and its ...
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270 views

mixture of maximally mixed and maximally entangled state

Consider the quantum system $\mathcal{B}(\mathbb{C}^d\otimes\mathbb{C}^d)$ and $|\psi\rangle=\frac{1}{\sqrt{d}}\sum_{i=0}^{d-1}|i,i\rangle$ be the (standard) maximally entangled state. Consider the ...
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Quantum entanglement vs classical analogy

Consider that we have two balls, one white and one black, and two distant observers A and B with closed eyes. We give the first ball to the observer A and the second ball to the observer B. The ...
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Conservation of quantum coherence?

Is coherence conserved under unitary transformation? As we saw in the process of generating entanglement, coherence between states of the subsystem is transferred to quantum correlations (related to ...
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Optical Parametric Amplifier performance compared to Optical Parametric Oscillator

I am trying to design a bright source of polarization entangled beams of photons so that it is visible to human eye. I have to decide between OPA and OPO. OPAs are cheap and simple to develop compared ...
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Entanglement for Gaussian states

Let us consider the product Fock space $\Gamma(\mathbb{C}^m) \otimes \Gamma(\mathbb{C}^n)$ and consider Gaussian states in that space. While reading some literature on Gaussian state entanglement ...