Hottest Questions This Month

6

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3

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647

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Quantum advantage with only Clifford gates (Gottesman Knill theorem)

answered Oct 11 at 13:53 Aryan Blaauw 1

2

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4

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393

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How is a Toffoli gate built without using T gates?

circuit-construction gate-synthesis clifford-group

answered Sep 29 at 5:07 sohamb172 144

5

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2

answers

305

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What is the computational complexity in initializing a quantum register?

qiskit quantum-state complexity-theory

answered Oct 8 at 12:15 epelaaez 2,354

3

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2

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590

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Why is there there an infinite number of possible bases but only a finite number of measurement outcomes

quantum-state

answered 2 days ago glS♦ 15.2k

5

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2

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294

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When can pairs of states be transformed into other pairs of states via unitary mapping?

quantum-gate quantum-state unitarity

modified Oct 5 at 13:33 DaftWullie 40.9k

6

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2

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243

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Minimum number of 2 qubit gates to build any unitary

circuit-construction mathematics quantum-circuit universal-gates

answered Sep 25 at 10:55 Nikita Nemkov 726

1

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3

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390

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Is there any simple mathematical proof that measurement destroys entanglement?

entanglement measurement

modified Oct 7 at 23:06 Adam Zalcman 9,265

2

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3

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78

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Why can no pair of single qubits look like $\frac{1}{\sqrt2}(|00\rangle+|11\rangle$)?

entanglement textbook-and-exercises

answered Oct 7 at 18:20 Martin Vesely 9,863

3

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2

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237

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How to express real matrices as linear combinations of unitaries?

vqe linear-algebra

modified Oct 6 at 5:50 Sajal 43

3

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2

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230

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Why do stabilizer codes in Nielsen and Chuang have Pauli X and Z matrices?

stabilizer-code

answered Oct 6 at 17:50 Craig Gidney 15.8k

3

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1

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287

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Why does quantum distinguishability ensure no faster-than-light communication?

quantum-state measurement nielsen-and-chuang faster-than-light

modified yesterday glS♦ 15.2k

5

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159

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Quantum communications and "knowledge" of receiving a qubit

quantum-state physical-realization communication

answered Sep 22 at 7:35 Jaswin 203

2

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2

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236

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What is the circuit for grover's algorithm if N is not a power of 2?

algorithm circuit-construction grovers-algorithm

answered Sep 24 at 18:50 Sam Jaques 1,166

5

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1

answer

250

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What is the motivation for using dual lattice in the surface code?

error-correction stabilizer-code surface-code

modified Oct 11 at 5:40 Adam Zalcman 9,265

9

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1

answer

115

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What does the paper "Training Variational Quantum Algorithms Is NP-Hard (Phys. Rev. Lett. 127, 120502)" mean?

algorithm vqe qaoa

modified Sep 28 at 17:01 jecado 638

2

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2

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172

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Proof for Cardinality of the Clifford Group

quantum-state density-matrix unitarity pauli-gates clifford-group

modified Oct 5 at 6:33 Mark Wildon 153

1

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2

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218

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How does Equation (9) follows from these definitions?

quantum-state textbook-and-exercises bloch-sphere

answered Sep 26 at 21:03 Martin Vesely 9,863

3

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1

answer

240

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Controlled Z gate using Pauli rotation operators and Z tensor product Z

circuit-construction pauli-gates

modified Sep 20 at 9:31 glS♦ 15.2k

3

votes

1

answer

229

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Using distinguishability of non-orthogonal states to create a cloning device

textbook-and-exercises no-cloning-theorem

modified Oct 7 at 10:53 DaftWullie 40.9k

4

votes

2

answers

54

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Can error correction for a classical algorithm with bit flips be easier than for a general quantum circuit?

error-correction classical-computing classical-quantum

answered Oct 11 at 17:14 user440774 31

2

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2

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213

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How can we measure a quantum system when the sum of amplitudes-squared does not equal one?

quantum-state measurement

modified Oct 4 at 13:18 Peter Mortensen 127

1

vote

1

answer

124

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Getting non-Clifford after performing several Clifford gates in qiskit

qiskit programming quantum-gate circuit-construction clifford-group

modified Oct 6 at 22:36 Adam Zalcman 9,265

2

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1

answer

120

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Is the CNOT in the standard three-qubit circuit for the GHZ state necessary?

quantum-gate quantum-state entanglement hadamard state-preparation

modified Sep 27 at 6:55 glS♦ 15.2k

2

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3

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185

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General conditions to define a logical operator: is there some general characterization of those elements (from group theory for instance)

error-correction stabilizer-code

modified Sep 30 at 17:15 Jonathan Trousdale 3,022

3

votes

1

answer

81

views

How are two photons entangled in the Xanadu computer?

photonics optical-quantum-computing continuous-variable quantum-optics linear-optics

answered Oct 5 at 13:36 Ziofil 176

1

vote

2

answers

80

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Find a unitary to prepare state $|0\rangle$ to a specific vector

qiskit quantum-state mathematics linear-algebra

modified Oct 3 at 22:03 user1271772 10.8k

1

vote

2

answers

195

views

How to analyze the following quantum circuit?

entanglement measurement quantum-circuit matrix-representation

modified Sep 27 at 17:50 Tristan Nemoz 1,408

6

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1

answer

90

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Are SIC-POVMs optimal for quantum state reconstruction?

measurement tomography povm quantum-metrology mub

modified Oct 6 at 12:04 Markus Heinrich 1,743

0

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3

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70

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Which quantum computing frame is suitable for optimization problems?

qiskit programming q# cirq

modified Oct 9 at 9:33 narip 1,529

3

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1

answer

88

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Why are all the eigenvalues of a "Hermitian block-encoding" equal to $\pm1$?

algorithm unitarity eigenvalue

modified Sep 23 at 7:25 glS♦ 15.2k

7

votes

1

answer

89

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Are projective measurements the only optimal measurements to discriminate between two states?

quantum-state measurement povm state-discrimination

modified Sep 27 at 8:09 glS♦ 15.2k

3

votes

1

answer

69

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Can quantum search be performed without phase estimation?

grovers-algorithm phase-estimation

modified Sep 22 at 6:27 glS♦ 15.2k

6

votes

1

answer

110

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Do entangled measurements across multiple copies help in state distinguishability?

quantum-state entanglement measurement probability state-discrimination

modified Sep 28 at 13:31 glS♦ 15.2k

2

votes

1

answer

57

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Showing that $e^{i \sigma_z \otimes \sigma_z t} = \text{CNOT}(I \otimes e^{i \sigma_zt})\text{CNOT}$

mathematics pauli-gates

modified Sep 22 at 6:28 glS♦ 15.2k

4

votes

1

answer

73

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What is the structure of coefficients of $2^N\times 2^N$ unitary matrices decomposed in terms of the Pauli basis?

mathematics unitarity pauli-gates linear-algebra

modified 2 days ago Danylo Y 4,610

4

votes

2

answers

68

views

What are introductory resources to learn about quantum computing hardware?

resource-request physical-realization

answered Sep 22 at 16:26 Catalina 21

3

votes

1

answer

41

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How to apply Euler's formula to $Z$ rotations such as $e^{i\pi/8 Z}$?

qiskit quantum-gate

answered Sep 22 at 17:17 forky40 3,187

3

votes

1

answer

84

views

Implement the classical shadow coding error?

qiskit programming algorithm tomography shadow-tomography

modified Sep 23 at 23:11 forky40 3,187

5

votes

1

answer

50

views

What does it mean for a channel to be independent of the input state?

quantum-operation physical-realization open-quantum-systems

modified Sep 20 at 9:32 glS♦ 15.2k

3

votes

1

answer

81

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Can I use the Lie product formula to simulate the Hamiltonian of an adjacency matrix by using the QPE to take Nth roots of permutation matrices?

mathematics hamiltonian-simulation phase-estimation

answered Sep 18 at 20:44 Quantum Mechanic 1,509

2

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1

answer

102

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Major Security proofs available for Device-Independent QKD

resource-request cryptography key-distribution qkd

modified Oct 1 at 8:29 Rammus 3,472

4

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1

answer

68

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What is an algorithm to generate random error in depolarizing channel

error-correction quantum-operation depolarizing-channel

modified Oct 3 at 14:09 glS♦ 15.2k

6

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1

answer

49

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Resources for QRAM implemented as a subroutine for quantum algorithm

resource-request quantum-memory

answered Oct 4 at 23:39 Dr. Sarah Kaiser 814

1

vote

1

answer

62

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Is it possible to perform $z$ rotation in Qiskit with just $x$ and $y$ rotations?

qiskit programming quantum-gate circuit-construction

modified Oct 3 at 11:41 glS♦ 15.2k

3

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1

answer

62

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What are the problems of linear inversion quantum state tomography?

resource-request tomography

modified Oct 6 at 14:37 Mateus Araújo 1,335

3

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1

answer

37

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Using Classical Shadow to predict quantum state's fidelity has nothing to do with the dimension of the density matrix?

tomography shadow-tomography

modified Oct 11 at 8:09 Markus Heinrich 1,743

2

votes

2

answers

47

views

What is the name of this "ancilla based" process to implement gates

quantum-gate teleportation

modified Oct 8 at 9:50 Craig Gidney 15.8k

2

votes

2

answers

36

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Optimal decompositions of some standard multi-qubit gates

resource-request gate-synthesis quantum-circuit transpile

modified Oct 12 at 9:24 Nikita Nemkov 726

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