# Tagged Questions

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### Low rank entangled states

In some recent works, I got the information that low rank mixed states need not be bound entangled. In particular, for the system $3\otimes 3$ there is no bound entangled states. Can anyone tell me ...
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### What is known about the trace of two copies of a channel / four copies of an isometry

Let $\mathcal{E} : \mathcal{L}(A) \to \mathcal{L}(B)$ be a completely positive trace preserving map. By the Choi–Jamiołkowski isomorphism there is an isometry $J : A \to B \otimes C$ such that ...
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### Can Werner states have bound entanglement?

Let us consider the maximally entangled state $$|\psi\rangle=\frac{1}{\sqrt{n}}(|0,0\rangle+\cdots+|n-1,n-1\rangle)$$ and construct the pseudo-pure state ...
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### Experimental realization of Quantum Teleportation of Spin, not polarization, not ions or atoms

I've looked everywhere in databases my school provides, to google searches, to the questions asked in physics forums, and here. As I understand, the original QT (quantum teleportation) protocol ...
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### Quantum Mechanics in terms of *-algebras

I'm currently trying to find my way into the geometric description of Quantum Mechanics. I therefor started reading: Geometry of state spaces. In: Entanglement and Decoherence (A. Buchleitner et ...
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Recently, I have been studying a quantum protocol for the "Hidden Matching" problem that makes use of states that can be expressed as $|\psi\rangle=\frac{1}{\sqrt{n}}\sum_{i=1}^n ... 1answer 131 views ### How can you distinguish between projections of quantum states? Consider this problem in quantum cryptography: We have two pure states$\phi_1,\phi_2$as input and constants$0 \leq \alpha <\beta \leq 1 $, where "Yes instances" are those for which ... 0answers 82 views ### Looking for description of Helstrom's measurement I hope someone can help me find the page or chapter where Helstrom discusses his famous measurement for distinguishing between two mixtures in the textbook Quantum Detection and Estimation Theory. ... 1answer 92 views ### States diagonal in the tensor product of Bell states. Bell-diagonal states are 2-qubit states that are diagonal in the Bell basis. Since those states lie in$\mathbb{C}^{2} \otimes \mathbb{C}^{2}$, the Peres-Horodecki criterion is a sufficient condition ... 1answer 60 views ### Functional relations for Kochen-Specker proofs Many proofs of the Kochen-Specker theorem use some form of the following argument (from Mermin's "Simple Unified Form for the major No-Hidden-Variables Theorems" ) [I]f some functional relation ... 7answers 661 views ### Quantum information science references I was hoping you guys could recommend reading material on Quantum Information Science. First off, here's my background. Personally, I started reading Ballentine's Quantum Mechanics and I found it be ... 1answer 85 views ### Many body quantum states analyzed as probabilistic sequences Measurements of consecutive sites in a many body qudit system (e.q. a spin chain) can be interpreted as generating a probabilistic sequence of numbers$X_1 X_2 X_3 \ldots$, where$X_i\in ...
Every density matrix of $n$ qubits can be written in the following way \hat{\rho}=\frac{1}{2^n}\sum_{i_1,i_2,\ldots,i_n=0}^3 t_{i_1i_2\ldots i_n} ...