User user1936752

9 votes

1 answer

470 views

Quantum attack on hash functions

asked Oct 25, 2018 at 14:48

7 votes

1 answer

381 views

Why does Google's quantum processor outperform IBM's?

quantum-advantage ibm google-sycamore

asked Oct 23, 2019 at 14:15

7 votes

1 answer

165 views

Bob applies a projector - what happens to eigenvalues of Alice's reduced state?

quantum-state mathematics density-matrix partial-trace projection-operator

asked Oct 20, 2020 at 2:17

7 votes

1 answer

188 views

Closest quantum state with a fixed marginal: Analytical solution?

quantum-state density-matrix optimization fidelity partial-trace

asked Dec 19, 2021 at 9:17

6 votes

3 answers

1k views

What is the location of the Qiskit config file?

qiskit programming

asked Nov 6, 2019 at 19:03

6 votes

2 answers

302 views

Balanced vs unbalanced superposition distinguisher

algorithm deutsch-jozsa-algorithm

asked Nov 5, 2018 at 21:23

6 votes

2 answers

2k views

How to find the operator sum representation of the depolarizing channel?

nielsen-and-chuang quantum-operation textbook-and-exercises kraus-representation

asked Dec 16, 2018 at 20:35

5 votes

3 answers

599 views

Intuitive role of the polar decomposition in proof of Uhlmann's theorem for fidelity

nielsen-and-chuang fidelity

asked Nov 9, 2018 at 10:55

5 votes

1 answer

722 views

Getting a layout for qubits in Qiskit

qiskit

asked Dec 4, 2019 at 18:22

5 votes

0 answers

108 views

Connection between smooth max-relative entropy and smooth max-information

entropy information-theory

asked Sep 4, 2020 at 19:01

5 votes

1 answer

73 views

What is the quantum analogue of $P_{XY} = P_{Y|X}P_X$

quantum-state information-theory probability

asked Feb 3 at 6:56

5 votes

2 answers

48 views

What is the form of a unitary $U$ that preserves the marginals on a given state, $\text{Tr}_A(U\rho_{AB} U^\dagger) = \rho_B$?

quantum-state unitarity tensor-product

asked Dec 7, 2021 at 9:28

5 votes

1 answer

203 views

Trace distance between mixed state and pure state vs trace distance between their purifications

quantum-state information-theory fidelity partial-trace trace-distance

asked May 30, 2021 at 5:55

5 votes

1 answer

180 views

Closeness of purifications of states

information-theory fidelity trace-distance linear-algebra

asked Nov 21, 2020 at 16:15

5 votes

1 answer

142 views

Does $\mathcal E^{\otimes n}$ admit a more efficient Stinespring dilation than the one used for $\mathcal E$?

quantum-operation tensor-product information-theory linear-algebra

asked Dec 10, 2020 at 19:20

5 votes

1 answer

61 views

Upper bounding a permutation invariant state

quantum-state mathematics information-theory

asked Mar 30, 2021 at 9:47

4 votes

0 answers

118 views

Calculating the entropy of a quantum state

entropy information-theory partial-trace

asked Jan 8, 2021 at 9:25

4 votes

1 answer

70 views

Non-lockability of quantum max-entropy

entropy partial-trace information-theory max-entropy

asked Sep 23, 2020 at 16:43

4 votes

1 answer

93 views

Is there a higher dimensional Fredkin gate?

quantum-gate circuit-construction unitarity

asked Nov 8, 2021 at 17:31

4 votes

1 answer

61 views

Quantum channel between two states with inaccessible reference - when can it be done?

quantum-state quantum-operation information-theory

asked Jan 26 at 6:41

4 votes

1 answer

142 views

Can vectorization lead to mixed states?

quantum-state mathematics textbook-and-exercises

asked Dec 2, 2018 at 20:26

4 votes

0 answers

98 views

Forbidden/allowed outputs of a quantum channel

quantum-operation optimization entropy semidefinite-programming

asked Jan 27, 2020 at 19:10

4 votes

1 answer

101 views

Questions about the relation between max-relative entropy $D_{\max}(\rho||\sigma)$ and max-information

information-theory entropy max-entropy relative-entropy

asked Mar 25, 2020 at 19:30

4 votes

0 answers

142 views

Schumacher compression - comparing with Shannon compression

entropy communication information-theory

asked Apr 24, 2020 at 22:27

4 votes

1 answer

139 views

How to maximise over linear functionals of quantum channels?

quantum-operation optimization

asked Jan 16, 2020 at 11:31

3 votes

1 answer

366 views

What does a "Choi state" where we relax the partial trace condition represent?

quantum-state quantum-operation

asked Jan 21, 2020 at 13:41

3 votes

0 answers

102 views

Convexity of coherent information - erroneous argument!

entropy information-theory

asked Jan 23, 2020 at 17:42

3 votes

0 answers

69 views

Proof that quantum entanglement does not increase the asymptotic capacity of classical channel

entanglement quantum-operation

asked Dec 9, 2019 at 13:30

3 votes

1 answer

99 views

Going from a circuit to the quantum state output of the circuit

quantum-gate error-correction

asked Jul 29, 2019 at 16:09

3 votes

1 answer

344 views

What exactly is the relation between the Holevo quantity and the mutual information?

quantum-state quantum-operation information-theory channel-capacity mutual-information

asked Aug 7, 2019 at 17:54

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75 Questions

Quantum attack on hash functions

Why does Google's quantum processor outperform IBM's?

Bob applies a projector - what happens to eigenvalues of Alice's reduced state?

Closest quantum state with a fixed marginal: Analytical solution?

What is the location of the Qiskit config file?

Balanced vs unbalanced superposition distinguisher

How to find the operator sum representation of the depolarizing channel?

Intuitive role of the polar decomposition in proof of Uhlmann's theorem for fidelity

Getting a layout for qubits in Qiskit

Connection between smooth max-relative entropy and smooth max-information

What is the quantum analogue of $P_{XY} = P_{Y|X}P_X$

What is the form of a unitary $U$ that preserves the marginals on a given state, $\text{Tr}_A(U\rho_{AB} U^\dagger) = \rho_B$?

Trace distance between mixed state and pure state vs trace distance between their purifications

Closeness of purifications of states

Does $\mathcal E^{\otimes n}$ admit a more efficient Stinespring dilation than the one used for $\mathcal E$?

Upper bounding a permutation invariant state

Calculating the entropy of a quantum state

Non-lockability of quantum max-entropy

Is there a higher dimensional Fredkin gate?

Quantum channel between two states with inaccessible reference - when can it be done?

Can vectorization lead to mixed states?

Forbidden/allowed outputs of a quantum channel

Questions about the relation between max-relative entropy $D_{\max}(\rho||\sigma)$ and max-information

Schumacher compression - comparing with Shannon compression

How to maximise over linear functionals of quantum channels?

What does a "Choi state" where we relax the partial trace condition represent?

Convexity of coherent information - erroneous argument!

Proof that quantum entanglement does not increase the asymptotic capacity of classical channel

Going from a circuit to the quantum state output of the circuit

What exactly is the relation between the Holevo quantity and the mutual information?