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1

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27

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Is there a way to reverse the amplitudes of a quantum system?

modified 15 hours ago Blue♦ 6,210

1

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1

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18

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Cannot load account with Qiskit

qiskit

answered 19 hours ago James Wootton 6,557

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1

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63

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What is the meaning of the state $|1\rangle-|1\rangle$?

quantum-gate quantum-state notation

modified yesterday Blue♦ 6,210

3

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1

answer

43

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Garbage-Free Reversible Binary-To-Unary Decoder Construction

algorithm circuit-construction

modified yesterday Craig Gidney 4,356

1

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0

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17

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Qiskit gates in LaTeX representation: notation meaning [on hold]

quantum-gate qiskit notation

modified yesterday Blue♦ 6,210

9

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0

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71

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Quantum machine learning after Ewin Tang

algorithm quantum-state machine-learning quantum-advantage

asked 2 days ago Alex 146

6

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0

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66

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How is Bell’s Inequality converted to the CHSH inequality?

quantum-information correlations

modified 2 days ago Bob 31

4

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1

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62

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Why do we use the quantum superposition for a period instead of factors in Shor's algorithm?

algorithm shors-algorithm quantum-fourier-transform superposition

answered 14 hours ago Sam Jaques 188

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1

answer

47

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Concurrence for a two qubit state

quantum-state quantum-information entanglement

modified 2 days ago DaftWullie 13.9k

2

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1

answer

27

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Consistent QISkit error: “All devices are currently unavailable”

programming qiskit ibm-q-experience

answered yesterday James Wootton 6,557

3

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1

answer

28

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How to add control to gates in Cirq?

programming cirq

modified Feb 18 at 22:50 Craig Gidney 4,356

3

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1

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34

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Partial Transpose and Positive Operators

quantum-information entanglement mathematics quantum-operation

modified Feb 18 at 16:59 Blue♦ 6,210

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50

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Why is Nielsen and Chuang book so popular in this field? [on hold]

nielsen-and-chuang

modified 2 days ago Tejas Shetty 14

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1

answer

60

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If CNOTs and single qubit gates are universal then why do we need to prove that controlled U operations can be composed by them as well?

quantum-gate gate-synthesis nielsen-and-chuang

modified Feb 18 at 11:49 DaftWullie 13.9k

4

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1

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37

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Creating .gifs corresponding to Quirk simulations

simulation quirk

answered Feb 17 at 21:23 Craig Gidney 4,356

7

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2

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82

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Equivalent unitary transformations

algorithm quantum-gate phase-kickback

modified Feb 17 at 14:19 AHusain 1,819

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87

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A two qubit state in a special form

quantum-state

modified Feb 16 at 23:20 Mithrandir24601♦ 2,336

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53

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Interaction of an RF pulse with transmon qubit

physical-qubit superconducting-quantum-computing

modified Feb 17 at 3:56 DanielSank 929

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0

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15

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Can one make NV centred type qubits from analogus materials in the periodic table?

physical-realization physical-qubit experiment chemistry

modified Feb 18 at 12:36 Blue♦ 6,210

4

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3

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75

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Why is there a difference between the simulation results and the actual quantum computer results?

simulation ibm-q-experience

answered Feb 14 at 18:30 Siddhānt Singh 1,003

7

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2

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74

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Simulate hamiltonian evolution

hamiltonian-simulation nielsen-and-chuang pauli-gates

answered Feb 18 at 8:24 DaftWullie 13.9k

1

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1

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73

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Can we teleport a human or send information faster than light using quantum teleportation?

quantum-information teleportation

modified Feb 16 at 18:51 Siddhānt Singh 1,003

3

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2

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165

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

quantum-gate gate-synthesis tensor-product

modified yesterday DaftWullie 13.9k

4

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0

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59

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Does Shor's algorithm end the search for factoring algorithms in the quantum world of computation?

algorithm shors-algorithm

modified 16 hours ago R. Chopin 530

3

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1

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22

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How to set a starting state in cirq?

programming cirq

modified Feb 15 at 18:13 Craig Gidney 4,356

2

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1

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83

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Decompose a general two-qubit gate into general controlled-qubit gates

quantum-gate circuit-construction gate-synthesis

modified Feb 13 at 23:07 Craig Gidney 4,356

1

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2

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66

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Is programming in quantum computer same as programming in quantum simulator in classical computer?

programming q#

answered Feb 12 at 17:48 Mariia Mykhailova 1,605

5

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2

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63

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Constructing a circuit which performs the transformation $|x,y\rangle$ $\rightarrow$ $|x, x + y\text{ mod } 4\rangle$

algorithm circuit-construction

modified Feb 11 at 20:17 ahelwer 1,791

8

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2

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2k

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Why is quantum Fourier transform required in Shor's algorithm?

algorithm complexity-theory shors-algorithm quantum-fourier-transform

modified Feb 8 at 15:33 Community♦ 1

6

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1

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90

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Is quantum computer equivalent to Turing machine with matrix multiplication oracle?

complexity-theory matrix-representation

modified Feb 14 at 16:53 ahelwer 1,791

2

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0

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49

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ProjectQ - In which part of the controlled gate object are the control bits scored

quantum-gate programming simulation

modified Feb 15 at 9:14 Blue♦ 6,210

3

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1

answer

24

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Using parametrised values and 'Symbols' in Cirq

programming cirq

modified Feb 14 at 23:02 Craig Gidney 4,356

8

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2

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105

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Fast way to check if two state vectors are equivalent up to Pauli operations

pauli-gates

modified Feb 11 at 19:13 Craig Gidney 4,356

6

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1

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28

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If $|\psi\rangle, U|\psi\rangle$ are known, how many pairs of such qubits are required to find the operator $U$?

quantum-gate quantum-state

modified Feb 12 at 15:42 Blue♦ 6,210

3

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1

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49

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Is it possible to create a superposition in IBMQ QISkit which has probability amplitudes $|a|\neq |b|$?

quantum-state qiskit

modified Feb 13 at 10:20 James Wootton 6,557

0

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1

answer

69

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Why does $|P_U − P_V |$ equal $\langle \psi |U^{\dagger} M U|\psi\rangle −\langle \psi |V^{\dagger} M V |\psi\rangle$?

quantum-gate quantum-state measurement nielsen-and-chuang

modified Feb 13 at 8:42 Josu Etxezarreta Martinez 1,573

6

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2

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96

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Who discovered the phase kickback trick?

history phase-kickback

answered Feb 9 at 0:13 Mark S 448

3

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1

answer

125

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Is there a polynomial quantum algorithm for graph coloring?

algorithm complexity-theory space-complexity

modified Feb 10 at 19:35 John Watrous 1,698

5

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0

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64

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Quantum teleportation with moving Alice and Bob

quantum-information teleportation

modified Feb 13 at 9:44 glS 4,071

3

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1

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50

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Do the probability amplitudes describe the probability of projective measurement?

quantum-state measurement

modified Feb 12 at 0:40 bilanush 85

8

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1

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77

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Current limits on Grover search space

architecture physical-realization grovers-algorithm ibmq

answered Feb 9 at 12:48 cnada 2,389

1

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3

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71

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Is it correct to say that we need controlled gates because unitary matrices are reversible?

quantum-gate unitarity

modified Feb 8 at 3:22 Blue♦ 6,210

3

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2

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92

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SWAP test inputs

quantum-gate circuit-construction

modified Feb 8 at 14:49 Aman 142

1

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1

answer

68

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QISKit warrning on marshmallow

programming qiskit

answered Feb 11 at 5:35 Leron Gil 31

2

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1

answer

51

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How to implement a $\frac{\theta}{2}$ rotation from $\theta$ rotation?

quantum-gate gate-synthesis quirk

answered Feb 10 at 20:29 Craig Gidney 4,356

4

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1

answer

53

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What resources are available for learning QCL?

programming resource-request

modified Feb 15 at 23:02 Stephane Rolland 105

6

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3

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392

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Is there any method of adding two operators in a circuit?

quantum-gate circuit-construction gate-synthesis quirk

modified Jan 31 at 14:29 James 150

2

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1

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56

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Is there a place online where I can catch up with all the notational syntax associated with quantum computing?

resource-request notation

answered Feb 10 at 7:30 Blue♦ 6,210

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