2022 Developer Survey is open! Take survey.

Quantum Computing Stack Exchange is a question and answer site for engineers, scientists, programmers, and computing professionals interested in quantum computing. It only takes a minute to sign up.

Sign up to join this community
Anybody can ask a question
Anybody can answer
The best answers are voted up and rise to the top

Explore our Questions

4 votes
0 answers
66 views

Implementing "computable phase shifts" using T Toffoli ( problem 4.1 from Nielsen and Chuang's)

2 votes
1 answer
45 views

What is the difference between $|+\rangle$ and $|-\rangle$?

1 vote
2 answers
30 views

How is the ket of a quantum state calculated in this code?

1 vote
1 answer
37 views

ket statevector of a 2-quibit system

0 votes
2 answers
48 views

How to sum equal terms in a superposition state?

2 votes
1 answer
42 views

How does the Pauli Y gate act in the $|+\rangle, |-\rangle$ basis?

8 votes
2 answers
727 views

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

1 vote
1 answer
47 views

Theta value passed as input to quantum phase estimation: qiskit textbook

0 votes
1 answer
44 views

Describe |00> and |10> in terms of |0> and |1>

11 votes
3 answers
4k views

How to calculate an Expected Value of some operator acting on qubits?

1 vote
1 answer
123 views

If density matrices are linear operators, what vectors do they operate on?

0 votes
1 answer
60 views

How to create a quantum circuit checking whether two functions $f$ or $g$ are of the same type?

2 votes
3 answers
210 views

Is there any difference between "value of a qubit" and its "state"?

1 vote
1 answer
48 views

Are the eigenvalues of projectors always zero and/or one?

Browse more Questions