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QuestionEverything
  • Member for 5 years, 11 months
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14 votes
3 answers
5k views

Density matrix after measurement on density matrix

6 votes
1 answer
559 views

BB84 Protocol Alice Choice to Bob

6 votes
1 answer
386 views

Is the quantum state fidelity defined as $F(\rho, \sigma)=\text{tr}\sqrt{\rho^{1/2}\sigma\rho^{1/2}}$ or its square?

5 votes
2 answers
2k views

Physical Interpretation of Pauli Matrices as Polarization Check

5 votes
1 answer
418 views

How to calculate the conditional min-entropy via a semidefinite program?

5 votes
1 answer
279 views

Semi-definite program for smooth min-entropy

5 votes
2 answers
193 views

How are the eigenvalues of $\rho=\frac12(|a\rangle\!\langle a| +|b\rangle\!\langle b|)$ derived?

5 votes
2 answers
223 views

How to prove the positivity of the conditional quantum mutual information, $I(A;B|C)\ge0$?

4 votes
1 answer
472 views

Concavity of Conditional Quantum Entropy

4 votes
1 answer
80 views

How do I prove that $\newcommand{\tr}{\operatorname{Tr}}\tr(A \sqrt{B} A \sqrt{B}) = \tr\Big[\Big(\sqrt{\sqrt{B}} A \sqrt{\sqrt{B}}\Big)^2\Big]$?

4 votes
2 answers
1k views

'Rectilinear' and 'Diagonal' Basis in BB84 Protocol

4 votes
1 answer
867 views

What happens if I measure only the first qubit of a Bell state?

3 votes
1 answer
306 views

Trace distance of two classical-quantum states

3 votes
1 answer
376 views

How do I compute the Relative Entropy between pure and mixed states?

3 votes
1 answer
422 views

Trace of Hermitian Operator and Operator Function

2 votes
1 answer
457 views

Fidelity With Bell State Calculation

2 votes
2 answers
527 views

What happens when you send a Bell state through depolarizing channel?

2 votes
2 answers
1k views

Prove that the depolarizing channel is completely positive

2 votes
2 answers
482 views

Projecting $\lvert ++ \rangle$ on Bell Basis

2 votes
2 answers
225 views

Calculate probability of a state after depolarization

2 votes
1 answer
210 views

Depolarization of density operator with zeros in diagonal

2 votes
1 answer
149 views

Semi-definite program for conditional smooth max-entropy

2 votes
1 answer
344 views

Two qubit state + Depolarizing channel = Bell diagonal state?

2 votes
1 answer
180 views

Prove that for a cq-state $\rho_{XE}$, $H_\infty(X|E) \ge H_\infty(X) - \log|E|$

2 votes
1 answer
123 views

Prove that for a pure tripartite state $\rho_{ABE}$, $H(RB) = H(RE)$

2 votes
1 answer
87 views

Computing $H(Z|B)$ in a bipartite density matrix $\rho_{AB}$

1 vote
1 answer
362 views

Find inner product of two states given inner product of an orthogonal state

1 vote
0 answers
67 views

Linear and Logarithmic Constraint in Semidefinite Programming

1 vote
1 answer
31 views

Prove that $Tr(\chi(\rho_A) \log(\chi(\rho_A)) = Tr(\rho_A \log(\chi(\rho_A))$

1 vote
0 answers
32 views

States for Tight Maassen-Uffink Uncertainty Relation