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.

learn more… | top users | synonyms

1
vote
1answer
88 views

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 ...
2
votes
2answers
50 views

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 ...
0
votes
0answers
26 views

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 ...
3
votes
2answers
144 views

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 ...
4
votes
1answer
62 views

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 (...
0
votes
1answer
39 views

Does the Delayed Choice Quantum Eraser require the signal and idler photons to be entangled?

In everything I've read about the Delayed Choice Quantum Eraser Experiment, the descriptions talk about the BBO crystal splitting of the photon into two entangled parts. The signal photon of the pair ...
0
votes
1answer
166 views

Quantum Measurement of Entangled Time-Varying Systems

Suppose System A has a dynamic, continuous variable $O_A(t)$, which we wish to measure via a quantum probe. Assume system A has a self-Hmiltonian, $H_{SA}$ so that the evolving wave function of ...
0
votes
2answers
61 views

On significance of Quantum Entanglement

I'm a Software engineering bachelor student and hence i don't have a strong physical background. i've been recently studying material related to quantum computing and its underlying physics and i came ...
2
votes
1answer
68 views

Quantum teleportation of atomic states that involve energy [duplicate]

With quantum computing the concern is with information, and when quantum teleportation appears, the states being transferred are often spin states. However, there is an energy difference, even if ...
1
vote
0answers
47 views

Converting a Bell state to a less entangled state by LOCC [closed]

How can I convert a maximally entangled state, $ \frac {1} {\sqrt2} (|00\rangle +|11\rangle) $, to a less entangled state like, $$ cos(\theta)|u_0 v_0\rangle + sin(\theta)|u_1 v_1\rangle $$, by using ...
0
votes
0answers
44 views

Why does the interference patterns in delayed choice quantum eraser cancel out? Why/how does it have a phase shift?

Talking about this experiment https://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser#The_experiment_of_Kim_et_al._.282000.29 I am assuming that anyone able to answer my question is already ...
-1
votes
1answer
116 views

Why is particle superposition still part of quantum mechanics? [duplicate]

After reading an article on Schrodinger's Cat, it seems that if we take the environment as an observer, that superposition cannot occur because all atomic and subatomic entities would be observed all ...
2
votes
2answers
122 views

Why when we have GHZ, then we cannot send a qubit using teleportation technique? [closed]

Suppose the following example Alice has a qubit $|A\rangle$ and Bob has a qubit $|B\rangle$, then by teleportation technique we can send an unknown qubit state (i.e. $|\psi\rangle = \alpha |0\rangle ...
1
vote
0answers
54 views

Entanglement in laser beams [closed]

Recent experiments in entanglement of two laser beams using OPOs indicates higher level (photon group instead of pair) of entanglement. When a higher ensemble of photons are entangled there is no ...
1
vote
0answers
107 views

The link between non-locality and Heisenberg's uncertainty relations

I have recently found out1 that the concepts of non-locality and Heisenberg's uncertainty do not live independently of one another in Quantum Mechanics. In other words, roughly the idea goes as: the ...
0
votes
3answers
186 views

Quantum entanglement - problem with Bell's inequality [closed]

To ask the question, I will state the scenario first. Please let me know if the scenario is not described appropriately. The question is in the scenario itself. There are many questions marks in this ...
0
votes
1answer
53 views

Quantum Entanglement of Lee and Ron [duplicate]

Lee and Ron are born as perfectly identical twins except for Lee being left handed and Ron being right handed. Years after birth they are seperated, Lee moving to Latvia and Ron moving to Rwanda. At ...
1
vote
1answer
217 views

Single quantum particle in beam splitter, with different systems located in each channel

Suppose a quantum mechanical particle enters a beam-splitter, which sends its wave packets into two mutually orthogonal channels, $C_a$ and $C_b$. Suppose that $C_a$ also contains System A, with ...
0
votes
2answers
93 views

Does quantum entangled particle release energy when its “twin” is measured? [closed]

So I was just thinking a bit, and I came up with a couple of questions. As we all know the scenario: We have two quantum entangled particles. Let's call them A and B. We like to measure the state of ...
0
votes
0answers
34 views

Entanglement up to a finite distance

We do not have a theory which predicts the working distance of entanglement, and this distance is usually taken to be infinity. However, up to now, experiments have just rigorously confirmed ...
3
votes
1answer
86 views

Beyond usual quantum mechanic description of entanglement, is there any QFT or stringy formalism/explanation of it? [closed]

Currently entanglement is speculated to be one underlying mechanism of emergent spacetime, but what are its foundations?
2
votes
1answer
82 views

Entanglement, superposition, and propositional logic [duplicate]

From what I am understanding, there is entanglement in a system if there is a correlation between elements of that system. For an example that I found, If you have only two cards and know that one is ...
1
vote
3answers
83 views

Is it probable for particles to become entangled under natural conditions?

Under what circumstances could particles become entangled without our intervention? How frequent would that have happened in the various stages of cosmic expansion? Is it possible that particles may ...
1
vote
0answers
36 views

Why is entanglement such a big deal? [duplicate]

I just learned about it to some depth (not very much, just the basics), and I fail to see why is this phenomenon considered strange or unexpected and the like at all. I mean let's consider a bag with ...
2
votes
2answers
149 views

What patterns could be observed in this quantum entanglement thought experiment?

Please see attached image below. The DEVICE is beaming two streams of entangled particle pairs (B1 and B2) in opposite directions (e.g.: Particle no. 1 (p1) goes left, Particle no. 2 (p2) goes right,...
0
votes
0answers
43 views

A New Approach to Quantum Entanglement Communication [duplicate]

I've read other posts on the feasibility of quantum entanglement as a means of communication so I'll save repeating what's already been said. Typically it seems to be shut down as an option because ...
3
votes
2answers
69 views

Entangle more than two atoms?

Alright so we know that we can entangle any two atoms, however, what exactly is stopping us from entangling more? In theory, shouldn't we be able to entangle a third to the already entangled pair? ...
4
votes
1answer
85 views

A question about the universal quantum cloning machine (UQCM)

In the recent paper Replicating the benefits of Deutschian closed timelike curves without breaking causality, a quantum state cloner based on open timelike curve (OTC) was mentioned. There to clone ...
4
votes
1answer
76 views

Is it possible to make a state tomography of an entangled state only by measurements on subsystems?

As far as I can understand, to make a state tomography of a composite system, a properly selected set of joint measurements should be carried out on the composite system to estimate the density matrix ...
2
votes
1answer
98 views

What's wrong with my Quantum Early Warning System (Thought Experiment) [closed]

I'm a lay physics enthusiast and I came up with a thought experiment that I can't fully wrap my head around: Alice and Bob are worried about an impending attack by the dreaded Xenomorphs, so they ...
1
vote
0answers
37 views

Modified double slit experiment with single entangled particle [closed]

Say we use one of the entangled particle (A) for the experiment, if we measure the other particle (B) would particle (A) still be able to exhibit interference pattern since physically only the ...
1
vote
1answer
107 views

How to understand the measurement on entangled state in the following cases? [closed]

Assuming an EPR pair AB, event MA is a measurement on A. My questions are: (1) At MB and MB' (depending on where B is located), if we try to describe the state of B (but not measure B yet), what'...
1
vote
0answers
37 views

Quantum entangled particles [closed]

Do we understand why particles are paired with specific other ones? Were they born together or existed right next to one another at another time? Can they pick (entangle) with new ones? Do we have ...
2
votes
0answers
46 views

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....
3
votes
1answer
151 views

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 ...
4
votes
1answer
70 views

entanglement of different types of particles possible?

Perhaps this question makes no sense physically, but is it theoretically possible to entangle a photon with an electron, for example? I know that entanglement links a specific property of particles, ...
8
votes
1answer
144 views

Entanglement and the Pauli exclusion priciple

Could you say that two electrons in the ground state of a helium atom experience quantum entanglement? They are both in the same energy level and cannot have the same quantum numbers. If one is spin ...
1
vote
2answers
149 views

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 ...
1
vote
3answers
115 views

What is wrong with this method for FTL communication? [duplicate]

I've seen the other questions, but almost all of them deal with manipulating quantum states so that the other person reads a message in the data. However, you cannot force a quantum state on ...
3
votes
1answer
58 views

Quantum entanglement and superdense encoding etc

Is the following a somewhat correct analogy for what these phenomenae are? Imagine a box of thousands of apples where exactly half of each apple is red and the other half is green. Each apple is ...
1
vote
2answers
111 views

Can you force the spin measurement on an electron?

Can you force an electron spin to be up or down so that when you measure it, you know what you will expect? I imagine that with an entangled electron pair, forcing the spin on one would enable faster ...
3
votes
1answer
55 views

The entanglement of a two dimensional particle and the one of two one dimensional particles

Case 1: Usually, entanglement is a correlation between more than one particles. For example, the momentum $p_1$ of the particle $1$ and the one $p_2$ of the particle $2$ have the relation that $p_1 +...
-1
votes
2answers
176 views

What stands behind the quantum nonlocality appearing in entanglements, and why Bell's inequalities are violated?

I noticed the question whether Bell's inequalities are based on a false premise, (Could Bell's Theorem be based on a false premise?) but I bring another argumentation of the question. Also I ...
1
vote
1answer
57 views

Coincidence count probability in the entanglement-enabled delayed choice experiment

I'm trying to understand the entanglement-enabled delayed choice experiment and I'm kind of stuck at the term "coincidence count probability" which I can't seem to find definition of. Their full set ...
1
vote
0answers
26 views

In a superradiant laser, how does the collective dipole store the coherence of the photons?

In a standard laser, the stimulated emission is largely incoherent. How does a superradiant laser get around this? To my understanding, a magnetic field is usually applied to align the dipole moments ...
5
votes
1answer
117 views

What is the greatest observed distance between clearly entangled particles?

As far as I can understand, decoherence will break entanglement. Given that, what is the greatest distance between entangled pairs, that has been successfully observed? Is it possible to identify ...
1
vote
0answers
84 views

Quantum indirect measurement with probes

I am wondering about the following hypothetical example regarding quantum measurements made by probes: An open, two-plate capacitor, in a LC circuit, has charge, q, that we want to measure. Each of ...
1
vote
1answer
154 views

Which is a good and short book for foundations of quantum mechanics? [duplicate]

I am looking for a book that has stuff on quantum states, entanglement, etc. I am aware of the book, Geometry of Quantum States. I have read Ballentine's book, Quantum Mechanics: A modern development
1
vote
1answer
105 views

If Alice is moving at relatavistic speeds compared to Bob, is collapse still simultaneous?

I have read some papers about experimental proof of non-locality involving a laser that goes through a beam-splitter and then each "half" goes to an observer (traditionally "Alice" and "Bob"). It has ...
2
votes
1answer
132 views

What is the “monogamy principle” in enganglement?

What does the "monogamy" principle imply? At a superficial level, it seems to say that a particle can be entangled with at most one other particle. However, I keep reading that several particles are ...