# Tag Info

### Can we use entangled particles to find out what is going on inside a black hole?

This is a version on steroids of the famous Einstein–Podolsky–Rosen Paradox. In General Relativity, to get out of a black hole requires you to move faster than light, so your question can essentially ...
• 9,621
1 vote

### FTL signaling by direction?

Yes, that would be FTL communication, but no it is not possible to do. To convince yourself, ask yourself: If person A measures first, which measurements can person B do, to tell which axis A measured ...
• 4,271
1 vote

• 3,155

### Where does the black hole firewall energy come from?

The firewall is a thought experiment stressing an incompatibility between previous agreed pictures, few actually consider it an actual physical entity. The common belief is that some of the ...
• 4,300

### Where does the black hole firewall energy come from?

No one really has a good answer to this because the firewall is only theortical with no expieimental evidence to back it up. (It is a seperate question if evidence even could exist in the first place ...
• 1,713
Accepted

### Entanglement entropy of the infinite transverse field Ising chain at the critical point

These few-site entropies tend to converge fairly fast with finite size, because they ultimately depend on very local physics. If you switch to DMRG you should easily see the values converge fully. You ...
• 1,958

### What Class of Interactions, excluding spontaneous pair creation, Entangle two particles

The confusion here seems to be a mix of classical and quantum terminology. You discuss the most famous multi-particle system with no entanglement (neglecting the Schwinger effect), which is a pair of ...
• 5,014
1 vote

### Mixed separable state with a continous probability distribution

The key point here is Caratheodory's theorem: If a state can be written as a convex combination of tensor products of density matrices, such as your integral, then it can also be expressed as a convex ...
• 17.1k
1 vote

### Questions on Bell's theorem and Disproving the hidden variable theory

I'm going to update part your RSA token analogy to reflect the experimentally observed behavior of entangled particles. Hopefully this helps demonstrate why the hidden-variables theory doesn't work. ...
• 121
Accepted

### How does the many-worlds interpretation solve spooky action at a distance?

In the Everett Interpretation (often called the Many Worlds Interpretation), when an 'observer' system interacts with an 'observed' system in a superposition of states, the result is that the observer ...
1 vote
Accepted

### Quantum extremal surface and black hole evaporation inquiry

First of all you are looking at the calculation of the generalised entropy of the black hole radiation inside the cutoff region. The paper then goes to do the calculation of the region beyond the ...
• 4,300
1 vote
Accepted

### Mixed separable state with a continous probability distribution

Yes, provided that $$\int p(a)\ \text{d}a = 1$$ the mixed state defined in terms of such an integral represents a valid separable state.
• 12.3k
1 vote

### Understanding Entanglement basis change in a practical sense

You've made this harder than it needs to be by choosing $R$ and $L$ with different lengths. You can always replace a state vector with a parallel vector of the same length without affecting any ...
• 12.7k
1 vote

### Representation of an entangled state

I think your confusion stems from what is the system and what is the state. The system is the measurement apparatus, which sometimes leaves the state of the particles unchanged if it happens to be ...
• 893
Accepted

### What is meant by the term "elements of physical reality" used by EPR paper?

The original article by Einstein, Podolsky and Rosen includes the following paragraph: The elements of the physical reality cannot be determined by a priori philosophical considerations, but must be ...
• 5,365
1 vote

### What is meant by the term "elements of physical reality" used by EPR paper?

Every particle has “elements of physical reality”. We couldn’t detect them if they didn’t. These elements, also known as variables could be as simple as mass, velocity, direction, angular momentum/...
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### 2 qubit entanglement in a QC

Generally speaking, the practical limitations of quantum computing are in the form of noise, and quantum decoherence, both of which occur due to interaction with the environment. Noise in quantum ...
• 33

### What is meant by the term "elements of physical reality" used by EPR paper?

The widely accepted view of nature of reality is that of copenhagen interpretation(please correct me if I am wrong!) I am not sure whether it is "widely accepted" today. Bohr and company ...
• 28.8k