Hottest Questions This Month

9

votes

2

answers

845

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Where is the parallelism in Deutsch-Jozsa algorithm?

quantum-gate deutsch-jozsa-algorithm

modified Nov 17 at 10:16 glS 11.4k

4

votes

2

answers

449

views

What's meant by the depth of a quantum circuit?

modified Nov 2 at 9:53 Glorfindel 510

1

vote

2

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292

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How do I create an inverse identity gate?

quantum-gate circuit-construction pauli-gates universal-gates clifford-group

answered Nov 24 at 11:10 Martin Vesely 6,620

7

votes

3

answers

122

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What can I conclude about $\langle \phi|\pi_1\pi_2|\phi\rangle$ if $\langle \phi|\pi_i|\phi\rangle\ge e$?

measurement projection-operator

modified Nov 19 at 17:02 Jonathan Trousdale 2,528

4

votes

2

answers

271

views

How to realize SWAP operation using iSWAP gate?

quantum-gate circuit-construction

modified Nov 24 at 14:20 glS 11.4k

3

votes

2

answers

333

views

How does the CX gate work?

quantum-gate programming

modified Nov 22 at 16:53 glS 11.4k

4

votes

2

answers

106

views

Is the trace distance between multipartite states invariant under permutations?

quantum-state partial-trace trace-distance

modified Nov 26 at 17:58 glS 11.4k

0

votes

3

answers

68

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Why 2 $H$ gates in series create a probability of 100% for one value of the qubit and 0% of the second value of the qubit?

quantum-gate hadamard

modified Nov 10 at 17:18 glS 11.4k

6

votes

3

answers

136

views

Shor's algorithm: initialization of second register

circuit-construction shors-algorithm quantum-fourier-transform

modified Nov 18 at 22:36 glS 11.4k

3

votes

3

answers

70

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How are the IBM's and Google's Hadamard gates fabricated and operated?

physical-realization hadamard ibm superconducting-quantum-computing google-sycamore

answered Nov 12 at 5:39 KAJ226 2,718

3

votes

3

answers

114

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How can I construct a 2-qubit state using single qubit gates and CNOT gate?

quantum-gate quantum-state circuit-construction

modified Nov 10 at 17:33 glS 11.4k

2

votes

2

answers

108

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Transforming $|01 \rangle + |10 \rangle - |11 \rangle \to |01 \rangle - |10 \rangle + |11 \rangle$

quantum-gate quantum-operation pauli-gates hadamard

modified Nov 10 at 17:39 user13760 3

3

votes

1

answer

273

views

How can I simulate Hamiltonians composed of Pauli matrices?

quantum-gate circuit-construction hamiltonian-simulation pauli-gates

modified Nov 10 at 17:35 glS 11.4k

1

vote

2

answers

157

views

What is the result of measuring $\sigma_x$ on the state $|01\rangle+|10\rangle$?

quantum-state entanglement measurement textbook-and-exercises

modified Nov 18 at 21:10 glS 11.4k

5

votes

1

answer

128

views

Closeness of purifications of states

information-theory fidelity trace-distance linear-algebra

answered yesterday John Watrous 3,203

2

votes

3

answers

95

views

What is a unitary operator that makes all the amplitudes all negative on the arbitrary state of $n$ qubits?

quantum-state circuit-construction

answered Nov 20 at 19:04 Appo 51

0

votes

4

answers

179

views

Import Qiskit fails [closed]

qiskit programming

modified Nov 22 at 16:53 glS 11.4k

3

votes

3

answers

78

views

How to identify index $k$ when presented with a state $\vert \psi_k\rangle$ from orthonormal states $\{\vert \psi_i\rangle\}_{1\le i\le n}$?

measurement

modified Nov 10 at 20:17 Mateus Araújo 405

2

votes

2

answers

93

views

Does 1 qubit correspond to 2 bits?

classical-computing superdense-coding

answered 9 hours ago keisuke.akira 1,313

2

votes

2

answers

109

views

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

quantum-gate quantum-state quantum-operation

modified Nov 4 at 15:49 glS 11.4k

5

votes

2

answers

51

views

Simulator-dependent implementations in Q#

programming q#

answered Nov 27 at 5:15 Craig Gidney 10.5k

3

votes

2

answers

64

views

Transforming $|100\rangle$ state into $|000\rangle + |111\rangle$ state using only Hadamard and CNOT gates

quantum-gate circuit-construction entanglement hadamard quantum-circuit

modified Nov 17 at 16:24 glS 11.4k

2

votes

2

answers

80

views

Properties of composition of isometry and a perturbed adjoint

fidelity trace-distance linear-algebra

answered Nov 12 at 16:17 tsgeorgios 936

0

votes

2

answers

71

views

How to perform the unitary transformation $U|i,j_1\rangle = 1/\sqrt{k}(|i,j_1\rangle+|i,j_2\rangle+|i,j_3\rangle…+|i,j_k\rangle)$?

quantum-gate quantum-state unitarity

modified Nov 23 at 17:06 glS 11.4k

1

vote

2

answers

94

views

Question about a circuit from “Quantum Computing for Computer Scientists”

quantum-gate programming grovers-algorithm quantum-circuit

modified 10 hours ago LPenguin 113

2

votes

1

answer

71

views

What is the probability of finding the second qubit as $0$ in the state $|\psi\rangle=\frac1{\sqrt2}|00\rangle+\frac12|10\rangle-\frac12|11\rangle $?

quantum-state measurement textbook-and-exercises

modified Nov 22 at 17:01 glS 11.4k

-1

votes

3

answers

91

views

University Project - Quantum computing and it's social impact? [closed]

resource-request applications

modified Nov 12 at 21:20 Greenstick 583

2

votes

1

answer

90

views

Toffoli circuit explanation [closed]

quantum-gate qiskit programming

modified Nov 10 at 17:19 glS 11.4k

2

votes

2

answers

53

views

Does it make sense to sum two Choi operators?

quantum-state quantum-operation

answered Nov 26 at 18:12 user2723984 817

3

votes

2

answers

108

views

Is there an explanation for why, to search through an unstructured database, the average number of checks is $\frac{N}{2}$ in classical computation?

grovers-algorithm classical-computing

modified Nov 19 at 10:03 glS 11.4k

5

votes

1

answer

50

views

Difference between Bell's inequality and CHSH

entanglement bell-experiment non-locality foundations

modified Nov 10 at 17:28 glS 11.4k

3

votes

1

answer

82

views

Confused about the application of Hadamard gate to uncorrelated qubits [duplicate]

qiskit hadamard

modified Nov 3 at 14:13 luciano 785

3

votes

2

answers

48

views

$S^{\dagger}$ gate in Q#

q#

modified Nov 18 at 6:16 luciano 785

3

votes

2

answers

99

views

Traveling salesman problem in Qiskit: cannot find a solution on simulator

qiskit programming ibm-q-experience quantum-computing-for-finance

modified Nov 10 at 17:17 glS 11.4k

3

votes

2

answers

60

views

Proof of the no-communication theorem

measurement density-matrix communication

modified Nov 4 at 16:00 glS 11.4k

4

votes

1

answer

57

views

(Why) does unconditionally secure multi-party quantum computation imply quantum bit commitment?

cryptography

answered Nov 4 at 16:49 Martti Karvonen 151

1

vote

2

answers

91

views

Which Gate set can be used to perform the function $U|0\rangle =\frac{1}{\sqrt{n}}\sum_{i=0}^{n}(|i\rangle)$?

quantum-gate quantum-state circuit-construction

modified Nov 19 at 9:53 glS 11.4k

3

votes

1

answer

91

views

Qiskit Inverse of a quantum fourier transformation

qiskit circuit-construction quantum-fourier-transform

modified Nov 18 at 9:05 glS 11.4k

2

votes

2

answers

68

views

What is the “sum-over-paths” picture of quantum computing?

resource-request simulation interpretations

modified Nov 26 at 14:04 ahelwer 3,233

4

votes

1

answer

51

views

Does the quantum Jensen-Shannon divergence appear in any quantum algorithms or texts on quantum computing?

resource-request density-matrix entropy information-theory classical-quantum

modified Nov 4 at 20:37 glS 11.4k

2

votes

1

answer

65

views

Depolarization of density operator with zeros in diagonal

quantum-state density-matrix noise linear-algebra depolarizing-channel

answered Nov 8 at 19:53 keisuke.akira 1,313

1

vote

3

answers

50

views

Why, in a discrete-time quantum walk,we first apply the tensor product of the coin operation with the identity?

quantum-walks

answered Nov 6 at 8:35 DaftWullie 34.2k

3

votes

3

answers

77

views

How to learn parameters in a quantum circuit, given an interference pattern?

programming cirq machine-learning tfq

modified Nov 16 at 10:30 Calum Macdonald 31

1

vote

2

answers

74

views

What is $\sum_{i}\langle i \vert U \vert j\rangle$ for unitary $U$?

mathematics textbook-and-exercises unitarity linear-algebra

modified Nov 26 at 11:27 glS 11.4k

1

vote

2

answers

57

views

How to find original matrix from eigenbasis and eigenvalues?

matrix-representation

modified Nov 14 at 7:28 Martin Vesely 6,620

2

votes

1

answer

55

views

Gate cancellations in Hamiltonian simulation

hamiltonian-simulation quantum-control

modified Nov 20 at 6:29 KAJ226 2,718

0

votes

1

answer

68

views

Quantum Phase estimation with $2\pi$ replaced with $2e$

qiskit ibm-q-experience phase-estimation

answered Nov 12 at 20:25 C. Kang 1,256

3

votes

1

answer

67

views

Question about Haar random quantum states

quantum-state information-theory probability

modified Nov 23 at 8:04 David Bar Moshe 1,704

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