User Mahathi Vempati

9 votes

1 answer

1k views

How can we be sure that for every $A$, $A^\dagger A$ has a positive square root?

asked Dec 2, 2018 at 11:28

9 votes

1 answer

451 views

Building Intuition for Relative Von Neumann Entropy

asked Dec 19, 2018 at 7:08

7 votes

2 answers

684 views

Is the set of all states with negative conditional Von Neumann entropy convex?

asked Dec 19, 2018 at 6:29

7 votes

3 answers

1k views

How do you send an array of qubits to an operation in Q#?

asked Jun 30, 2018 at 19:36

7 votes

4 answers

1k views

Maximally mixed states for more than 1 qubit

asked Nov 1, 2018 at 16:33

7 votes

2 answers

213 views

Are there disadvantages in using the inner product between states instead of the fidelity?

asked May 14, 2019 at 19:49

7 votes

2 answers

353 views

Diagrammatic Quantum Reasoning: Proving the loop equation using yanking equations

asked Dec 29, 2019 at 11:23

6 votes

3 answers

2k views

Partial trace over a product of matrices - prove that ${\rm Tr}(\rho^{AB}(\sigma^A\otimes I))={\rm Tr}(\rho^A\sigma^A)$

asked Dec 25, 2018 at 8:15

6 votes

2 answers

650 views

How does $\mathcal E(\rho)=\mathrm{Tr}_{env}[U(\rho\otimes\rho_{env})U^\dagger]$ turn into $P_0\rho P_0+P_1\rho P_1$?

asked Dec 17, 2018 at 6:28

5 votes

2 answers

139 views

Ways in which $\frac{1}{\sqrt 2} (|00\rangle + |11\rangle)$ can be expressed as $\frac{1}{\sqrt 2} (|uu\rangle + |vv\rangle)$

asked Dec 21, 2018 at 12:46

5 votes

1 answer

184 views

What are the standard eigenvalues in $\mathbb{C^2}\otimes\mathbb{C^2}$?

asked Jun 29, 2018 at 14:15

5 votes

2 answers

265 views

Shannon entropy is least when Measurement basis = Mixture basis

asked Dec 16, 2018 at 18:55

5 votes

1 answer

286 views

Equivalent determinant condition for Peres-Horodecki criteria

asked Jun 15, 2019 at 5:45

5 votes

2 answers

1k views

Why are $d^2$ dimensions required to describe a density matrix?

asked Dec 6, 2019 at 15:06

4 votes

1 answer

347 views

Difference between change of basis in bra-ket notation and matrix notation

asked Nov 4, 2020 at 13:01

4 votes

1 answer

91 views

Structural Physical Approximation of Partial Transpose

asked May 21, 2019 at 9:45

4 votes

1 answer

238 views

Are entanglement witnesses of this form optimal?

asked May 12, 2019 at 9:16

4 votes

1 answer

269 views

Proving the inequality $|\mathrm{tr}(AU)|\le \mathrm{tr}|A|$ in Uhlmann's theorem

asked May 13, 2019 at 19:48

4 votes

1 answer

329 views

How are witness operators physically implemented?

asked May 14, 2019 at 7:35

4 votes

0 answers

100 views

Deutsch Algorithm on a Quantum Turing Machine

asked Nov 4, 2018 at 16:29

4 votes

1 answer

161 views

How to find a separable decomposition for $|\Psi^+\rangle\!\langle\Psi^+|+|\Phi^+\rangle\!\langle\Phi^+|$?

asked Feb 27, 2019 at 9:23

4 votes

1 answer

199 views

Differentiate between local and global unitaries

asked Mar 1, 2019 at 7:03

4 votes

1 answer

217 views

How is the expression for the optimal entanglement witness derived?

asked Apr 2, 2019 at 10:50

3 votes

0 answers

80 views

What do you specify when you physically apply a unitary?

asked Jan 13, 2019 at 12:50

3 votes

1 answer

244 views

For 2x2 and 2x3 systems, is the partial transpose the only positive but not CP operation?

asked Feb 18, 2019 at 13:15

3 votes

1 answer

225 views

What can we know about the eigenvalues of a reduced density matrix knowing the eigenvalues of the original matrix?

asked Nov 2, 2019 at 20:44

2 votes

1 answer

114 views

What is the relevance of preservation of trace in completely postive trace preserving (CPTP) maps?

asked May 8, 2019 at 7:02

1 vote

1 answer

156 views

Quantum Fourier Transform on two qubits: Non orthogonal outputs

asked Sep 17, 2018 at 13:42

1 vote

2 answers

735 views

How to write a post-measurement state, if we don't know the measurement result?

asked Dec 14, 2018 at 10:46

Stack Exchange Network

29 Questions

How can we be sure that for every $A$, $A^\dagger A$ has a positive square root?

Building Intuition for Relative Von Neumann Entropy

Is the set of all states with negative conditional Von Neumann entropy convex?

How do you send an array of qubits to an operation in Q#?

Maximally mixed states for more than 1 qubit

Are there disadvantages in using the inner product between states instead of the fidelity?

Diagrammatic Quantum Reasoning: Proving the loop equation using yanking equations

Partial trace over a product of matrices - prove that ${\rm Tr}(\rho^{AB}(\sigma^A\otimes I))={\rm Tr}(\rho^A\sigma^A)$

How does $\mathcal E(\rho)=\mathrm{Tr}_{env}[U(\rho\otimes\rho_{env})U^\dagger]$ turn into $P_0\rho P_0+P_1\rho P_1$?

Ways in which $\frac{1}{\sqrt 2} (|00\rangle + |11\rangle)$ can be expressed as $\frac{1}{\sqrt 2} (|uu\rangle + |vv\rangle)$

What are the standard eigenvalues in $\mathbb{C^2}\otimes\mathbb{C^2}$?

Shannon entropy is least when Measurement basis = Mixture basis

Equivalent determinant condition for Peres-Horodecki criteria

Why are $d^2$ dimensions required to describe a density matrix?

Difference between change of basis in bra-ket notation and matrix notation

Structural Physical Approximation of Partial Transpose

Are entanglement witnesses of this form optimal?

Proving the inequality $|\mathrm{tr}(AU)|\le \mathrm{tr}|A|$ in Uhlmann's theorem

How are witness operators physically implemented?

Deutsch Algorithm on a Quantum Turing Machine

How to find a separable decomposition for $|\Psi^+\rangle\!\langle\Psi^+|+|\Phi^+\rangle\!\langle\Phi^+|$?

Differentiate between local and global unitaries

How is the expression for the optimal entanglement witness derived?

What do you specify when you physically apply a unitary?

For 2x2 and 2x3 systems, is the partial transpose the only positive but not CP operation?

What can we know about the eigenvalues of a reduced density matrix knowing the eigenvalues of the original matrix?

What is the relevance of preservation of trace in completely postive trace preserving (CPTP) maps?

Quantum Fourier Transform on two qubits: Non orthogonal outputs

How to write a post-measurement state, if we don't know the measurement result?