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20h
comment Operational difference between separable, entangled, PPT and NPT states
@anuraganshu I have fixed the link. That any non-separable 2x2 system can be distilled is shown in arxiv.org/abs/quant-ph/9607009. For 2x3, I don't know. Maybe you should ask a separate question.
20h
suggested rejected edit on Can isotropic states have bound entanglement?
20h
comment Can isotropic states have bound entanglement?
The states described here are isotropic states, not Werner states.
20h
revised Operational difference between separable, entangled, PPT and NPT states
deleted 9 characters in body
1d
comment Operational difference between separable, entangled, PPT and NPT states
@CuriousOne Pure state bipartite entanglement is indeed understood. The tricky part is mixed state entanglement.
1d
comment Operational difference between separable, entangled, PPT and NPT states
@CuriousOne Teleportation requires perfect entanglement. You can consider e.g. non-perfect teleportation and ask whether you can achieve a higher teleportation fidelity than with a LOCC protocol, but then it already starts getting very tricky.
1d
answered Operational difference between separable, entangled, PPT and NPT states
May
19
answered How can a correlation be teleported?
May
7
comment Toric Code and the String-Net Model
Any string-net model can be used as an error correcting code. The Toric Code is simply the easiest to realize (qubits, four-body stabilizers, simplicity of encoding/correction).
Apr
24
revised Can reduced density matrices of sub systems of an entangled composite system be different?
Added a missing "not"
Apr
24
suggested approved edit on Can reduced density matrices of sub systems of an entangled composite system be different?
Apr
22
comment Entanglement of coherent states
Note that your state lives in a 2-dimensional space spanned by $\vert\alpha\rangle$ and $\vert\beta\rangle$. It is thus (at least regarding its entanglement properties) equivalent to a problem of a two-qubit state with the correct overlap $\langle\alpha\vert\beta\rangle$. (In particular, it converges exponentially to a maximally entangled state as $\vert\alpha-\beta\vert\rightarrow\infty$.)
Apr
22
comment Entanglement of coherent states
Your state is entangled. However, it is not Gaussian, so you cannot characterize it by solely by its covariance matrix (as you have indeed observed).
Mar
8
comment Phase Transition at Zero Temperature (Not QPT)
I think the OP asks exactly for systems which have some kind of order at $T=0$ which immediately disappears at $T>0$, and I would say the Heisenberg model is exactly such an example. Whether this should be called a phase transition, I don't know.
Mar
7
answered Phase Transition at Zero Temperature (Not QPT)
Feb
26
comment Time evolution of a discrete 1-d lattice of spin-(1/2) particles under a given Hamiltonian, or special cases thereof
This makes this a rather broad question. If you only have nearest neighbor interactions, this is can be transformed to the XX model (or directly solved by mapping it to free fermions). If the $r_{ij}$ only act between even and odd sites, you can transform this to a model of hopping particles (but this can be hard to solve). --- In any case: Why do you call this a 1-d lattice? The way you write it there is no 1-d structure.
Feb
26
comment Time evolution of a discrete 1-d lattice of spin-(1/2) particles under a given Hamiltonian, or special cases thereof
Do you know anything about $r_{ij}$? (If not, why is it a 1D lattice?)
Feb
26
comment How to connect these two formulations regarding the need for a density matrix in quantum mechanics?
en.wikipedia.org/wiki/Purification_of_quantum_state
Feb
24
comment Expression of density operator
@Urgje I see. How can you avoid that your basis $\lvert u_k\rangle$ of $\mathcal H$ contains un-normalizable states? What would happen if you would choose plain waves as your basis?
Feb
23
comment Tensor product notation in quantum mechanics
Well, if $1$ and $2$ stood for the electrons in state $a$ and $b$, respectively, this would make perfect sense.