User GaussStrife

6 votes

3 answers

378 views

Interpretation of the unitaries involved in the eigenvalue decomposition of a density operator

asked Sep 15, 2021 at 16:17

6 votes

1 answer

89 views

Prove that $|(\langle \psi|_{A} \otimes \langle \phi|_{B})|\theta\rangle_{AB}|^{2}<1$ for entangled $|\theta\rangle_{AB}$

quantum-state entanglement mathematics linear-algebra inner-product

asked Dec 14, 2021 at 20:21

5 votes

1 answer

364 views

How can the Holevo bound be used to show that $n$ qubits cannot transmit more than $n$ classical bits?

quantum-state entropy information-theory

asked Aug 1, 2020 at 17:48

3 votes

0 answers

100 views

Circuit to construct a $n$-qubit state which is a superposition of states with only a single qubit being $\lvert1\rangle$ [duplicate]

quantum-gate quantum-state gate-synthesis

asked Nov 2, 2018 at 13:30

2 votes

1 answer

79 views

Under what situation is $\sum_{i} p_{i}S(\rho_i)$ > 0

entanglement entropy

asked Jun 12, 2020 at 12:40

2 votes

2 answers

166 views

Meaning behind obtaining a hermitian operator for measurement in another basis?

mathematics measurement textbook-and-exercises

asked Jul 20, 2020 at 14:50

2 votes

1 answer

30 views

Showing that $S(\rho_{XB}||\sigma_{XB})=\sum_{x}p(x)D(\rho_{B}^{x}||\sigma_{B}^{x})$ for classical-quantum states

entropy classical-quantum relative-entropy

asked Sep 22, 2021 at 11:31

2 votes

1 answer

57 views

What can be said about the non-negativity of the relative entropy of $S(\rho_{AB}||\rho_{B})$?

quantum-state quantum-operation information-theory entropy relative-entropy

asked Aug 27, 2021 at 11:56

2 votes

1 answer

46 views

$N(\frac{1}{2},2)=3$ for vectors in a Hilbert Space

quantum-state bloch-sphere

asked Aug 18, 2020 at 15:03

2 votes

1 answer

82 views

How is $S(\rho)=H(p_{i})+\sum_{i}p_{i}S(\rho_{i})\le \log(d)$ possible if $\rho_{i}$ are not pure states?

mathematics textbook-and-exercises entropy

asked Aug 23, 2020 at 15:43

2 votes

2 answers

58 views

How does a $d\times\ell$ matrix of rank $\ell$ and with singular values all equal to 1 imply it is maximally entangled

entanglement matrix-representation

asked Oct 9, 2020 at 11:00

2 votes

0 answers

60 views

Question regarding bloch vector solutions for master equation on page 388 of N&C

textbook-and-exercises nielsen-and-chuang bloch-sphere

asked Mar 29, 2021 at 14:48

2 votes

1 answer

39 views

How does $F(\psi, \phi) = [\sum_{x}\sqrt{p(x)q(x)}]^{2}$ [duplicate]

information-theory fidelity

asked May 17, 2021 at 17:12

2 votes

0 answers

28 views

Local operation to change the maximally mixed 2 qubit state to $\frac{1}{2}(|01\rangle \langle01|+|10\rangle \langle10|)$?

non-locality games quantum-discord

asked May 26 at 16:34

1 vote

1 answer

61 views

Moving between $\sum_{I}E_{i}=I$ and $\sum_{i}M^{\dagger}M=I$ for non-hermitian $M$

measurement povm

asked May 19, 2021 at 16:45

1 vote

0 answers

44 views

How is $I(\rho^{QC})=I_{CC}(\rho^{QC})$

quantum-operation kraus-representation mutual-information

asked Aug 12, 2021 at 11:22

1 vote

1 answer

57 views

Confused regarding explanation of Schumachers compression in N&C

quantum-operation nielsen-and-chuang

asked Jul 13, 2020 at 12:30

1 vote

2 answers

139 views

How does one go about constructing a mixed entangled state?

entanglement

asked Jul 22, 2020 at 17:08

1 vote

1 answer

84 views

Proof of quantum data processing inequality in N&C on pg 566

nielsen-and-chuang textbook-and-exercises entropy

asked Aug 10, 2020 at 16:27

1 vote

1 answer

55 views

Confusion over HSW theorem depicted in Nielsen and Chuang

quantum-state quantum-operation nielsen-and-chuang

asked Jun 19, 2020 at 16:26

0 votes

1 answer

53 views

Question regarding part of the proof for the typical subspace theorem

error-correction nielsen-and-chuang

asked Jul 8, 2020 at 17:34

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21 Questions

Interpretation of the unitaries involved in the eigenvalue decomposition of a density operator

Prove that $|(\langle \psi|_{A} \otimes \langle \phi|_{B})|\theta\rangle_{AB}|^{2}<1$ for entangled $|\theta\rangle_{AB}$

How can the Holevo bound be used to show that $n$ qubits cannot transmit more than $n$ classical bits?

Circuit to construct a $n$-qubit state which is a superposition of states with only a single qubit being $\lvert1\rangle$ [duplicate]

Under what situation is $\sum_{i} p_{i}S(\rho_i)$ > 0

Meaning behind obtaining a hermitian operator for measurement in another basis?

Showing that $S(\rho_{XB}||\sigma_{XB})=\sum_{x}p(x)D(\rho_{B}^{x}||\sigma_{B}^{x})$ for classical-quantum states

What can be said about the non-negativity of the relative entropy of $S(\rho_{AB}||\rho_{B})$?

$N(\frac{1}{2},2)=3$ for vectors in a Hilbert Space

How is $S(\rho)=H(p_{i})+\sum_{i}p_{i}S(\rho_{i})\le \log(d)$ possible if $\rho_{i}$ are not pure states?

How does a $d\times\ell$ matrix of rank $\ell$ and with singular values all equal to 1 imply it is maximally entangled

Question regarding bloch vector solutions for master equation on page 388 of N&C

How does $F(\psi, \phi) = [\sum_{x}\sqrt{p(x)q(x)}]^{2}$ [duplicate]

Local operation to change the maximally mixed 2 qubit state to $\frac{1}{2}(|01\rangle \langle01|+|10\rangle \langle10|)$?

Moving between $\sum_{I}E_{i}=I$ and $\sum_{i}M^{\dagger}M=I$ for non-hermitian $M$

How is $I(\rho^{QC})=I_{CC}(\rho^{QC})$

Confused regarding explanation of Schumachers compression in N&C

How does one go about constructing a mixed entangled state?

Proof of quantum data processing inequality in N&C on pg 566

Confusion over HSW theorem depicted in Nielsen and Chuang

Question regarding part of the proof for the typical subspace theorem