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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Entanglement and the uncertainty principle

Suppose you have two maximally entangled particles. You measure the spin about the x axis of the first and the spin about the y axis of the second. But both spins cannot be known simultaneously, so ...
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Can any experiments NOT be done through the classic control-experimental groups method? [on hold]

The classic control-experimental groups method involves having a control group to measure what happens when everything is regulated, and then one or more experimental groups are used, each having one ...
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The “spooky action at a distance” and reference frame

It is often said that the measurement in EPR experiment is instant, as somehow described as "spooky action at a distance". However, the notation of equal time depends on reference frame, according to ...
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Entanglement of two particles with same values of the entangled parameters?

The question For an entangled state consisting of systems A and B, if A is measured when does the wavefunction at B collapse? contains next entangled state: If there are two systems A and B, with ...
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For an entangled state consisting of systems A and B, if A is measured when does the wavefunction at B collapse? [duplicate]

If there are two systems A and B, with an entangled state consisting of $$\mid \psi \rangle = \frac{1}{\sqrt{2}} (\mid \uparrow _A \rangle \,\, \otimes \mid \uparrow _{B} \rangle \,+ \mid \downarrow ...
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Is This A Working Time Machine? [duplicate]

picture taken from this video for those who do not like to click on youtube links youtube video - retrocausality through Double Slit & Bose The answer will probably be no, but i am interested ...
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Entanglement of coherent states

I am new to quantum optics and I am trying to understand whether coherent states of the field could be entangled. Let's consider, for example, a two-mode state: $|\psi^{AB} \rangle = \frac{1}{c} ...
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60 views

Evolution of Eigenstates when two spin systems are coupled

I would like to describe the following situation: We have two spin systems: Spin 1 ($S_1$) and Spin 1/2 ($S_2$). Now imagine you somehow change their interaction so that you can finetune the ...
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Bell inequality with triplet state

Is it possible to prove Bell inequality starting from a state formed from triplet states, i.e. $\frac{1}{\sqrt{2}}(|\uparrow>_A|\uparrow>_B+|\downarrow>_A|\downarrow>_B)$? If not, why? ...
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Geometric measure of entanglement for fermions or bosons?

For a system consisting of multiple components, say, a spin chain consisting of $N\geq 3 $ spins, people sometimes use the so-called geometric measure of entanglement. It is related to the inner ...
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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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Is entanglement a classical phenomena?

If I have an entangled state shared between two parties Alice and Bob $$\frac{1}{\sqrt{2}}|00\rangle+\frac{1}{\sqrt{2}}|11\rangle....(1)$$ then the reduced density operator of Alice's side is ...
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Quantum Entanglement

My book is generally being quite unclear about something. So firstly I know that if the system is not entangled, we can write its state as $|ab\rangle=|a\rangle|b\rangle$ (if we understand the ...
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Could Quantum Entanglement be related with gravitational interactions? [closed]

Particles are entangled when they share the same state and their properties become correlated. Interaction with one of them, by say measurement, is experienced instantly by the other. If we measure ...
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Is teleportation possible?

When I just learned about quantum entanglement, I read that if two electrons are in quantum entanglement and placed in two different places, the photon which interacted with one electron is teleported ...
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Is there a fundamental interaction responsible for quantum entanglement?

Quantum entanglement seems to share information between particles instantaneously, as well as characteristics of these particles through changes that occur in each particle. If forces transfer energy ...
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Particles interacting with distance invariant force [closed]

What happens if you have a bunch of particles interacting with distance invariant force between them? I was thinking about it in terms of slit experiments and quantum entanglement. Just say for ...
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Is the interference quantum mechanical superposition the same as entanglement? [duplicate]

Are the interference of two wave functions an equivalent way of saying that they are entangled?
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Entanglement entropy in (1+1)d field theory with dynamical critical exponent $z>1$

It was well known that for (1+1)d CFT(z=1) case, we can use the tool of conformal map to derive the formula of entanglement entropy for a finite interval: S ~ $c \log L$. L is the length of the ...
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Entanglement ladder algebra and quantization of entanglement

Usually in QFT, even optical quantum mechanics papers, usually resort to describe n-states in terms of the ladder algebra, plus a parameter for polarization, but the entanglement information is ...
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spooky nonlocal communication, or bad abstract?

I'm referring to this recent paper, "Experimental Proof of Nonlocal Wavefunction Collapse for a Single Particle Using Homodyne Measurements" by Fuwa et al. published in Nature Communications. ...
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Why does measuring the spin of an entangled particle cause it to become unentangle?

I've been taught that measuring the spin of an entangled particle causes it to become unentangled, but not how or why, so I'd like to know by what process this occurs. Is the cause known? If so, ...
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What laser and BBO are needed to create entangled laser streams?

I have been reading about entangled particles, lasers, the two slit experiment, etc. I really know nothing from physics (i.e. equations, formulas, theory); so please respond accordingly. From my ...
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Entanglement of Mixed Quantum State

As per Wikipedia: Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot ...
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Entanglement, real or just math?

I'm new here, actually this is my first question so I'll just get to it. In quantum entanglement when something acts on one particle the other one reacts also, just in reverse (more or less). From ...
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Study the center and interior of a black hole using quantum entanglement

Having just watched the latest in a long line of space movies; Interstellar tries to combat the problem of studying the center of a black hole and understanding what's going on inside. My question is, ...
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Thought experiment on graviton breaking the speed of light [closed]

The effect of gravity travels at the speed of light. Suppose we can entangle a pair of gravitons (which are only theoretical, but who knows for sure?) and separate them over a vast distance. Hold on - ...
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How do we know that quantum entanglement is instantaneous?

Is it a mathematical certainty demonstrated through some proof or is this simply what observation shows? How sensitive are the measurements that determines the "communication" (I know... It is not ...
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Faster than light signals and the price to be paid if we accept them : a very simple protocol

Most physicists currently understand entanglement as transferring information instantaneously, yet not violating causality. Is this really a satisfactory explanation, or should be look for something ...
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Is there any theoretical limit to the distance at which particles can remain entangled?

As for as I understand (which is admittedly very little) particles that are created together become entangled. Currently, the experiments using entangled particles are over relatively short distances ...
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How can quantum entanglement send information?

I don't believe this is a duplication (either that or I didn't understand the answers to the other questions). I understand when sending information via radio waves that the frequency or amplitude is ...
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222 views

A naive question about topologically ordered wavefunction?

Topological entanglement entropy (TEE, proposed by Levin, Wen, Kitaev, and Preskill) is a direct characterization of the topological order encoded in a wavefunction. Here I have some confusions, and ...
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What is the difference between maximally entangled and maximally mixed states?

To my understanding, mixed states is composed of various states with their corresponding probabilities, but what is the actual difference between maximally mixed states and maximally entangled states? ...
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Why is the distance in non-local entanglement for teleportation limited by time

In a recent paper, researchers described a system that can teleport a quantum state without the need for the entangled particles to actually "meet" each other. I'm reading, in particular, ...
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can we transfer data via quantum entanglement (likewise we communicate today) to a specific target

Today we rely on electromagnetic field for communication. I'm a entrepreneur, I want to know why we can't transfer data with this technology to transfer data from one place to another place. It can ...
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Would 2 entangled atoms decay at the same time?

I have a very basic understanding of entanglement and radioactivity. But say 2 uranium atoms are entangled and then 1 of them decays, what would happen? Would the other atom decay as well? Or if not ...
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Can entangled particles stay in sync when one of them is travelling near light speed?

Can entangled particles stay in sync when one of them is travelling near light speed? I ask this because it means that time would be experienced at different speeds for both particles and could allow ...
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What does inflationary theory explain which quantum entanglement cannot?

Introduction This is an honest question... I don't study inflationary theory extensively (This is an understatement) but I am lost as to why it was developed in the first place. Here is why: ...
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Entangled Photon (laser pointer)

From a laser pointer emission; is it creating entangled pairs of photon? is it possible to get more than "pair" entangled, like group of photons all entangled?
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Properties of controlled z-rotations

Given n qubit gate of the form c-z-z-z... (shorthand for c-z between qubit 1 and 2 followed by c-z between 1 and 3 and so on up to n qubits) it seems to be possible to find local unitaries which will ...
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An error in my understanding of entanglement

Based on my knowledge of quantum entanglement, I can set up a scenario which leads to a contradiction with the No-communication theorem. Please help me find the flaw. Suppose Alice wants to ...
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What Quantum Entanglement is NOT? [closed]

What are the most insightful experiments on Quantum Entanglement undertaken in the last few years showing what it is not? What insights did we gain from does constructive failures? Is there a current ...
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Are all properties entangled when one property is entangled?

When one or more particles are quantum entangled by say their spin property, do their other measurable properties (e.g., momentum, polarization, whatever?) become entangled as well?
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About long range entanglement [closed]

“topologically non-trivial” ground states have long-range entanglement. Is this possible to process the quantum information with help of the studies in topological non-trivial ground states for ...
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Explanation for the EPR-like paradox

I am trying to understand the process of Quantum Entanglement for use in Quantum computers. The problem I have is this: Suppose some nuclear process emits an electron-positron pair. Now after ...
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How are Superposition and Entanglement related?

How are Superposition and Entanglement related? I don't know much of Quantum Mechanics. I am CSE student and got started with this Quantum Computing. It is interesting! If anybody can help me on ...
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Does continuous observation of an entangled particle keep it locked in its current state?

If two particles are entangled, and one of the particles ParticleA is periodically polled or pulsed of for it's state, and the other particle ParticleB is polled for a duration in seconds, will the ...
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Could a travelling quantum object transport an on-board monitor to restitute information later? [closed]

Could a pair of identical "automated observers" such as a camera inside a capsule, be made to travel slowly along different paths, and then be recovered to play back a film of its on-board ...
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Is there a unitary, linear bijection between (1) Maximally Entangled and (2) Factorizable States?

Pretty much as the title says. I am interested in the two particle system, each particle having two dimensional quantum states; naturally if there is a generalisation I'd be interested in that too. ...
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Entanglement entropy vs entropy

I just read that if you have a pure density matrix state on a product space, then a way to define entropy in a subspace is to take the reduced density matrix state and define $S = 1- ...