All Questions
11
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Is there any restriction for locally mapping a given 2-qubit density matrix into a desired 2-qubit density matrix with lower entanglement?
Suppose we're given a 2-qubit density matrix($\rho_{4\times4}$). we can apply two local maps on each of these qubits seperatly. So the output is density matrix($\rho^{\prime}_{4\times4}$).
I'm ...
- 27
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35
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Lorentz invariance (LI) of time ordering operation
At Srednicki after eq. (4.10), we have a discussion about that the time ordering operation. Have to be frame inv. I.e it has to be LI.
He wrote that for timelike separation we don't have to worry ...
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1
answer
70
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Equivalence of two entangling operators with respect to local operators
Suppose that $U_1$ and $U_2$ are two (entangling) operators that act on a quantum system consisting of several qubits. Is there any criterion to tell if these two are equivalent up to applying ...
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115
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How do Lieb-Robinson Bounds talk about locality without the position operator?
So we know when one goes from QM to QFT Lieb Robinson bounds become micro causality. But micro causality is a statement on the commutators assuming they are space-like, time-like or light-like. ...
- 1,389
2
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193
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Conformal Field Theory and Vertex Operator Algebra
I am trying to understand CFT from the viewpoint of both math(in particular using VOA) and physics. Now, in Math, we use the VOA to make sense of fields corresponding to certain states. We define for ...
- 83
1
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43
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Why Locality meant jointly observable?
Tobias Osborne's lecture around 20:00, he mentioned that the ideal of "Locality" could be expressed as such
If $x-y$ were space-like, then for all observable $A_{j,x}$ and $A_{k,y}$ were ...
- 3,256
12
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2
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4k
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What is a local operator in quantum mechanics?
In quantum mechanics, what exactly is meant by "local" operator?
What about a "global" or a "non-local" operator? Are these the same?
Can you also also help me understand what exactly is a local ...
- 754
1
vote
1
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132
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Basic question about local algebras in AQFT
AQFT (algebraic quantum field theory) assigns "local algebras of observables" to bounded regions of spacetime, in particular to double-cone ("diamond") regions. These algebras' projection operators ...
- 163
8
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2
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602
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Does Microcausality follow from Lorentz Invariance?
In a Lorentz Invariant theory, does microcausality automatically hold?
In a free theory this is obvious. In an interacting theory I found some 'proof's in this paper: http://arxiv.org/abs/0709.1483
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- 766
13
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1
answer
665
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Explaining causal completion axiom in Haag-Kastler axioms?
There are several variants of the Haag-Kastler axioms for algebraic quantum field theory. Usually one associates an algebra $\mathcal{A}(O)$ to each open region $O$ of spacetime. An often-suggested ...
- 935
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197
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QFT basics for Klein-Gordon fields
I am teaching myself QFT from Peskin for next years maths course and I have two questions:
What is a c-number? Is it a complex number, and if so why does it mean, $[\hat{\phi}(x),\hat{\phi}(y)]~=~<...
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