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DaftWullie
  • Member for 6 years
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39 votes

How do I show that a two-qubit state is an entangled state?

38 votes
Accepted

What exactly is an oracle?

37 votes
Accepted

What is quantum gate teleportation?

28 votes

What is the "surface code" in the context of quantum error correction?

26 votes
Accepted

Significance of The Church of the Higher Hilbert space

23 votes
Accepted

What is the Helstrom measurement?

23 votes
Accepted

Has there been any truly ground breaking advance in quantum algorithms since Grover and Shor?

19 votes

What are examples of Hamiltonian simulation problems that are BQP-complete?

18 votes
Accepted

Is quantum cryptography safer than classical cryptography?

18 votes

Why can't there be an error correcting code with fewer than 5 qubits?

17 votes
Accepted

Why does the "Phase Kickback" mechanism work in the Quantum phase estimation algorithm?

17 votes
Accepted

Why doesn't the Gottesman-Knill theorem render quantum computing almost useless?

16 votes
Accepted

Is swap gate equivalent to just exchanging the wire of the two qubits?

16 votes
Accepted

Density matrices for pure states and mixed states

14 votes

What is postselection in quantum computing?

14 votes
Accepted

Why can the QFT be replaced by Hadamard gates?

13 votes
Accepted

How to reduce circuit elements of a decomposed $C^2(U)$ operation?

13 votes

Composing the CNOT gate as a tensor product of two level matrices

13 votes
Accepted

Is entanglement transitive?

13 votes
Accepted

Is entanglement necessary for quantum computation?

12 votes

Is quantum computing just pie in the sky?

12 votes

Hamiltonian simulation with complex coefficients

12 votes
Accepted

Is the Kraus representation of a quantum channel equivalent to a unitary evolution in an enlarged space?

12 votes
Accepted

How does the Grover diffusion operator work and why is it optimal?

12 votes
Accepted

Is the Solovay-Kitaev theorem relevant for modern hardware?

11 votes
Accepted

Proof that any unitary can be written as $U=e^{-iH}$ with $H$ Hamiltonian with bounded norm

11 votes
Accepted

How to compute the average value $\langle X_1 Z_2\rangle$ for a two-qubit system?

11 votes
Accepted

What happens if two separately entangled qubits are passed through a C-NOT gate?

11 votes
Accepted

How is Grover's algorithm used to estimate the mean and median of a set of numbers?

11 votes
Accepted

Arbitrary powers of NOT and SWAP

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