All Questions
Tagged with quantum-field-theory quantum-entanglement
73
questions
1
vote
1
answer
243
views
Vacuum flucutuations = local entanglement between quantum fields?
I'm puzzled by this statement by Dieter Zeh: "Various types of quantum fluctuations (in particular vacuum fluctuations, often visualized in terms of 'virtual particles') are used to describe ...
- 81
0
votes
2
answers
59
views
How can I construct a trivial product state in the continuum?
When working on the lattice it is easy to define a trivial product state. A state $|\psi\rangle$ is a trivial product state if it admits the following tensor decomposition,
\begin{equation}
|\psi\...
2
votes
1
answer
67
views
Operational meaning of mode dependence of mode-entanglement
In this paper, Vedral shows that the entanglement in second quantized states can depend on the choice of modes. As a simple example, he points out that the ground state of two non-interacting harmonic ...
1
vote
1
answer
130
views
Does the no signalling theorem in quantum mechanics beg the question?
I had always thought similarly and then came across a paper here that argues this.
The abstract is as follows:
Many authors state that quantum nonlocality could not involve any controllable ...
3
votes
0
answers
103
views
Decoherence time of quarks
I have been reading papers on using top quark's use as a probe for new physics using quantum information theoretic observables such as concurrence. One of the reasons they provide for using a top ...
- 309
4
votes
0
answers
128
views
Entanglement entropy in states with particle content
I am studying entanglement and its measurements in the context of a lattice model of the Dirac theory. The idea is that one has two bands, symmetric with respect to $E=0$, and the groundstate is ...
- 503
3
votes
0
answers
87
views
Is Von Neumann entropy in QFT related to the two-point function?
Suppose I have a scalar QFT. Is the Von Neumann entropy related to the two point function? More generally, given the two point function and an entangling surface, can we calculate the Von Neumann ...
- 672
1
vote
0
answers
45
views
Resource Recommendation for Quantum Information Theory especially entanglement in quantum field theory
I am trying to start learning quantum information from a theoretical point of view not involving aspects of quantum computing. The main thing that I want to understand is entanglement from both a ...
1
vote
0
answers
51
views
How is entanglement of non-spin variables incompatible with local realism?
It seems to me that spin/polarization entanglement is the only spooky one. That's because the entanglement of other observables would happen even in regular classical physics if we made a "...
- 2,475
2
votes
1
answer
128
views
What's wrong with my argument about entanglement entropy in QFT being time-independent?
Let's say we need to compute the entanglement entropy (EE) of a subsystem $A$ ($A=[0,L]$, $L>0$) in a 2D CFT.
The density matrix of the total system (i.e., the real axis) is given by
$$
\rho(t)=\...
- 51
2
votes
2
answers
773
views
Proof of the expression for entanglement entropy from correlation matrix
Let a quantum system be described by a correlation matrix
$$
C_{ij} = \langle c_i^\dagger c_j \rangle\ ,
$$
which we can split in components $A$ and $\bar{A}$. I have read that we can calculate the ...
- 601
2
votes
1
answer
108
views
Is the circuit unitary in Nielsen's method for calculating complexity?
I was trying to learn how to calculate circuit complexity (1707.08570) when I chanced upon a seemingly confusing concept. The "Nielsen method" involves looking at a unitary transformation $U$...
0
votes
0
answers
40
views
How to describe the entanglement in the jets?
Consider a pair of quark and anti quark flew away and generate the "jets"(whatever that meant).
But from the color conservation, it was assured that the seemly isolated jets that was ...
- 3,256
6
votes
0
answers
92
views
Can we determine when the lowest-energy state cannot be annihilated by any local operator, just by inspection of the Hamiltonian?
Relativistic quantum field theory (QFT) has the property that the lowest-energy state cannot be annihilated by any operator that is localized in a finite region of space (references 1,2,3). In other ...
- 54.5k
1
vote
0
answers
102
views
Hamiltonian basis in multiple particle systems
I have a question about the choosing of basis that compose the Hamiltonian of multiple systems. For example if we have a system of N particles, that depend in our case of Pauli matrixes i will give ...
- 529
3
votes
0
answers
96
views
Is it possible to peform thermodynamic work by harvesting entanglement from the vacuum?
I have already asked two questions on this topic:
1. What happens to the vacuum when entanglement is harvested? [closed]
and
2. Does entanglement harvesting require cooling the environment to ...
- 1,488
0
votes
0
answers
295
views
Good book to study entanglement in detail
Can anybody suggest a good book to know about quantum entanglement? I am a master's student and I have good knowledge of quantum mechanics. I want to know more on this subject. It would also be useful ...
2
votes
0
answers
126
views
Why does the no-cloning theorem imply the monogamy of entanglement?
I have seen papers where they mentioned that the monogamy of entanglement can be seen as a consequence of the no-cloning theorem. Could somebody sketch this out?
N.B.: I have seen the argument that ...
- 1,544
1
vote
1
answer
119
views
Constructing orthonormal bases in sub-Hilbert spaces of $L^2(\mathbb R)$ defined for particular spatial regions?
I've explored the entanglement of modes by expanding the ground-state solution of a many-body problem as an infinite sum of Slater determinants of one-particle Hermite functions. The one-particle ...
0
votes
1
answer
67
views
Can you entangle two electrical fields?
Lets say I have two already existing electrical fields. can I entangle them and cause one to influence another. (see image)
- 75
3
votes
1
answer
416
views
What happens to the vacuum when entanglement is harvested?
I stumbled upon this website which talks about entanglement harvesting. I also already asked a question on this subject regarding some experimental question. In this post I want to ask another ...
- 1,488
3
votes
2
answers
510
views
Does entanglement harvesting require cooling the environment to sufficiently low temperatures?
I stumbled upon this webpage, which describe a process they call "entanglement harvesting". I was wondering whether to observe this effect it is necessary to cool the environment to ...
- 1,488
1
vote
1
answer
220
views
Is incompatibility required for contextuality?
A preprint just came out claiming that incompatibilty is not requried to demonstrate generalized contextuality. My question isn't about generalized contextuality---which I don't quite understand---but ...
- 1,325
1
vote
1
answer
162
views
Why are maximally entangled continuous variable states not physical?
I have been going through this paper: https://arxiv.org/abs/quant-ph/9908056
There in, just after eq (1), it's mentioned that maximally entangled continuous variable states are not physical. Why is ...
- 367
1
vote
0
answers
100
views
How does QFT explain QM phenomena?
I've been studying QFT for a couple of years now, and until today I haven't encountered any of the phenomena that I've studied in my QM course: tunneling, entanglement, probability measurements and ...
- 5,931
1
vote
1
answer
253
views
How can anything be unentangled?
If the universe is made of fields that exist everywhere, won’t every point in the universe become entangled with those around it, expanding out at the speed of light? How could two systems nearby one ...
- 749
8
votes
0
answers
259
views
The emergence of space-time from entangled states
I recently read an article by Yasunori Nomura (https://arxiv.org/abs/1711.05263), in which he says that space-time is an emerging phenomenon. At the same time, space-time disappears when the ...
- 956
6
votes
4
answers
541
views
Changing the relative phase of two photons in an Hong-Ou-Mandel interference produces anti-bunching?
What happens to the output of a beam splitter when you change the relative phase between two photons that enter from the two input ports?
In Hong-Ou-Mandel interference for a beamsplitter of the form, ...
- 2,193
1
vote
1
answer
147
views
What is the form of a many-body hamiltonian that are subject to the measurement of the position?
Suppose there is a $N$ body hamiltonian, suppose $N=2$ for simplicity:
$$
H = - \frac{1}{2} \nabla_1^2 - \frac{1}{2} \nabla_2^2 + V(r_1,r_2) + \frac{1}{|r_1 - r_2|}.
$$
If we make a measurement for ...
- 1,356
5
votes
2
answers
131
views
Why does the entanglement of quantum fields depend on their distance?
When watching Seans Carrol's "A Brief History of Quantum Mechanics", he mentioned around the 50th minute (the video I linked to starts at that point) that
[about quantum fields in vacuum] .....
- 516