User keisuke.akira

17 votes

What is meant by the term "computational basis"?

answered Mar 29, 2018 at 3:35

9 votes

Accepted

What's the purpose of phases in quantum mechanics?

answered Jul 3, 2020 at 23:08

9 votes

Expected value of a Haar random quantum state multiplied by a unitary

answered Nov 7, 2020 at 8:01

8 votes

If all quantum gates must be unitary, what about measurement?

answered Mar 29, 2018 at 16:44

6 votes

Accepted

Grover's Algorithm on a Database with more than 50% matching entries

answered Jul 5, 2020 at 17:51

6 votes

Does 1 qubit correspond to 2 bits?

answered Nov 30, 2020 at 14:33

6 votes

Can SWAP operators change trace of a product state?

answered Aug 7, 2020 at 22:32

6 votes

Accepted

How close or far apart are the distributions generated by two Haar random states?

answered Jun 29, 2021 at 4:26

5 votes

What does the adjoint of a channel represent physically?

answered Jul 16, 2020 at 23:08

5 votes

Is there a lower bound on the average diamond norm of two uniformly random unitaries U1 and U1 of dimension D that are sampled from haar measure?

answered Jun 2, 2020 at 2:44

4 votes

How do the probabilities of each state change after a transformation of a quantum gate?

answered Mar 29, 2018 at 10:43

4 votes

Can you encode two values in a single qubit state, say its phase and orientation?

answered Jul 11, 2020 at 7:09

4 votes

Why do we divide by $\sqrt2$ in the qubit states $\lvert\pm\rangle=\frac{1}{\sqrt2}(\lvert0\rangle\pm\lvert1\rangle)$?

answered Jul 16, 2020 at 17:03

4 votes

Accepted

Prove that $A\preceq B$ implies $A=\Psi(B)$ for some channel $\Psi$

answered Jul 22, 2020 at 22:55

4 votes

Accepted

How do we perform a measurement of an arbitrary 1-qubit quantum state in any arbitrary orientation?

answered Aug 1, 2020 at 1:36

4 votes

What's the idea behind the unitary freedom of ensemble decompositions for density matrices?

answered Dec 9, 2020 at 14:05

4 votes

On the distribution of the fidelity of a random product state with an arbitrary many-qubit state

answered Jun 29, 2021 at 2:58

4 votes

Accepted

Depolarization of density operator with zeros in diagonal

answered Nov 8, 2020 at 19:53

3 votes

Accepted

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

answered Aug 5, 2020 at 21:43

3 votes

How can I find a quantum channel connecting two arbitrary quantum states?

answered Nov 3, 2020 at 22:25

3 votes

In shadow tomography, how is the state reconstructed from its shadows?

answered Dec 1, 2020 at 7:16

3 votes

Accepted

What is the set of all functions from ℤ to ℤ?

answered Jul 19, 2020 at 1:49

3 votes

Accepted

Relation between Wigner quasi-probability distribution and statistical second-moment

answered Jul 15, 2020 at 19:36

3 votes

Accepted

What experiments can distinguish between mixed and pure states?

answered Jul 1, 2020 at 21:20

3 votes

Can we say that an $n$-qubit system is entangled if at least one basis vector is missing?

answered Jun 15, 2020 at 6:45

3 votes

Is the trace norm monotone with respect to quantum operations?

answered Jun 30, 2021 at 5:32

2 votes

Accepted

Confusion over HSW theorem depicted in Nielsen and Chuang

answered Jun 20, 2020 at 8:36

2 votes

Prove that the depolarizing channel is completely positive

answered Jun 20, 2020 at 8:58

2 votes

Algorithm to find stabilizer states

answered Jun 30, 2020 at 20:34

2 votes

Can a Kraus representation act as the identity on any operator?

answered Jul 15, 2020 at 3:06

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36 Answers

What is meant by the term "computational basis"?

What's the purpose of phases in quantum mechanics?

Expected value of a Haar random quantum state multiplied by a unitary

If all quantum gates must be unitary, what about measurement?

Grover's Algorithm on a Database with more than 50% matching entries

Does 1 qubit correspond to 2 bits?

Can SWAP operators change trace of a product state?

How close or far apart are the distributions generated by two Haar random states?

What does the adjoint of a channel represent physically?

Is there a lower bound on the average diamond norm of two uniformly random unitaries U1 and U1 of dimension D that are sampled from haar measure?

How do the probabilities of each state change after a transformation of a quantum gate?

Can you encode two values in a single qubit state, say its phase and orientation?

Why do we divide by $\sqrt2$ in the qubit states $\lvert\pm\rangle=\frac{1}{\sqrt2}(\lvert0\rangle\pm\lvert1\rangle)$?

Prove that $A\preceq B$ implies $A=\Psi(B)$ for some channel $\Psi$

How do we perform a measurement of an arbitrary 1-qubit quantum state in any arbitrary orientation?

What's the idea behind the unitary freedom of ensemble decompositions for density matrices?

On the distribution of the fidelity of a random product state with an arbitrary many-qubit state

Depolarization of density operator with zeros in diagonal

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

How can I find a quantum channel connecting two arbitrary quantum states?

In shadow tomography, how is the state reconstructed from its shadows?

What is the set of all functions from ℤ to ℤ?

Relation between Wigner quasi-probability distribution and statistical second-moment

What experiments can distinguish between mixed and pure states?

Can we say that an $n$-qubit system is entangled if at least one basis vector is missing?

Is the trace norm monotone with respect to quantum operations?

Confusion over HSW theorem depicted in Nielsen and Chuang

Prove that the depolarizing channel is completely positive

Algorithm to find stabilizer states

Can a Kraus representation act as the identity on any operator?