Quantum Computing Stack Exchange

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14

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Am I doing anything wrong when trying to calculate the expectation value in Qiskit on the real hardware?

qiskit

asked 2 hours ago physavage 131

1

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0

answers

8

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Can a Kraus representation be always an identity to any operator?

quantum-information mathematics

asked 3 hours ago Amplituhedron 11

1

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1

answer

59

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How does the graphical notation used to denote doubly-controlled gates work?

quantum-gate matrix-representation notation

modified 3 hours ago M. Stern 1,759

0

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1

answer

14

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Randomness using simple parallel Hadamard circuit

measurement hadamard random-quantum-circuit

answered 3 hours ago Craig Gidney 9,147

1

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0

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16

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What is the pseudo threshold of a QECC using stabilizer formalism

quantum-information error-correction stabilizer-code terminology fault-tolerance

modified 5 hours ago El-Mo 119

2

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2

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145

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How do you implement a negative controlled gate using the regular controlled gate?

quantum-gate error-correction

modified 5 hours ago glS 10.2k

1

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2

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129

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Quantum Circuit explaination

circuit-construction graph-states

modified 6 hours ago glS 10.2k

0

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1

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38

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Question About How Qiskit Reset Gate Affects Other Entangled Qubits

quantum-gate qiskit programming ibm-q-experience measurement

modified 6 hours ago glS 10.2k

0

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1

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33

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How can I represent mixed states in Q#?

quantum-state programming q#

modified 6 hours ago glS 10.2k

1

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1

answer

54

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What extra functionality is available to an IBM Q Network member over a regular IBM Q Experience user

qiskit programming ibm-q-experience ibm

modified 6 hours ago glS 10.2k

1

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1

answer

28

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What is the representative matrix for a measurement in the Bell-state basis?

measurement bell-basis

modified 6 hours ago glS 10.2k

1

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1

answer

29

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Visualizing custom gates in Cirq

quantum-gate programming cirq

modified 6 hours ago glS 10.2k

1

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1

answer

21

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Applying a gate to all line qubits without explicitly listing them in Cirq

quantum-gate programming circuit-construction cirq

modified 6 hours ago glS 10.2k

0

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0

answers

12

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How to construct quantum circuit to count number of 0-qubits and 1-qubits

circuit-construction

asked 7 hours ago Isomorphism 1

3

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1

answer

48

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Is the Hilbert-Schmidt probability simply zero that a generic rank-2 two-qubit (“pseudo-pure”) density matrix is separable?

quantum-state quantum-information entanglement density-matrix

modified 7 hours ago Paul B. Slater 631

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1

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35

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Confused regarding explanation of Schumachers compression in N&C

quantum-information nielsen-and-chuang quantum-channel

modified 11 hours ago glS 10.2k

2

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0

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14

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Computing the expectation values of a Hamiltonian constructed from a cost functions in combinatorial optimization

algorithm optimization dynamics

modified 14 hours ago glS 10.2k

0

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1

answer

29

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Question regarding part of the proof for the typical subspace theorem

quantum-information error-correction nielsen-and-chuang

modified 15 hours ago glS 10.2k

2

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1

answer

73

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How to prepare a quantum circuit for $\frac{1}{\sqrt{3}}(|00\rangle+|01\rangle+|10\rangle)$ starting from $|00\rangle$

quantum-gate quantum-state circuit-construction entanglement

modified 16 hours ago glS 10.2k

4

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4

answers

527

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Nielsen and Chuang, Exercise 6.5: How to simulate oracle for n+1 qubits using one oracle gate for n qubits and one extra qubit?

grovers-algorithm nielsen-and-chuang oracles

answered 22 hours ago kianna 31

1

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1

answer

74

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Can quantum computing help to recover a lost private key?

programming

answered yesterday Jonathan Trousdale 1,786

3

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1

answer

33

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Is running a for loop faster on a quantum computer than a classical computer?

algorithm

answered yesterday Craig Gidney 9,147

1

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1

answer

45

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Quantum-Assisted Neural Network Training (Is my design reasonable?)

algorithm quantum-state machine-learning

modified yesterday Mridul 105

1

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1

answer

69

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Why after transpiling a Qiskit circuit we obtain a different result?

qiskit programming ibm-q-experience quantum-fourier-transform initialization

answered yesterday Paula G 131

2

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1

answer

73

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How to implement Cx mod N unitary

algorithm qiskit programming circuit-construction shors-algorithm

modified yesterday glS 10.2k

0

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1

answer

62

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How the simulator work?

quantum-gate quantum-state qiskit programming simulation

modified yesterday glS 10.2k

2

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2

answers

44

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Find the Kraus operators of a combined amplitude and phase damping channel

error-correction quantum-channel operator-sum

answered yesterday glS 10.2k

1

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1

answer

41

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What can be inferred about the closeness of reduced qubit states from the closeness of the bipartite quantum state?

quantum-state quantum-information density-matrix fidelity partial-trace

modified yesterday Niraj Kumar 97

1

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2

answers

52

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Is there anything Quantikz can do that Tikz cannot do?

quantum-gate circuit-construction

modified yesterday user1271772 6,939

6

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3

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106

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How to implement a while loop in a quantum computer?

algorithm physical-realization

modified yesterday Fleeep 267

4

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3

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78

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Can you transform a quantum program into an arrangement of slits?

programming

answered yesterday DaftWullie 30.6k

1

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3

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49

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Can you encode two values in a single qubit state, say its phase and orientation?

quantum-state

answered yesterday Aleksey Zhuravlev 25

-2

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1

answer

95

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Operations needed for successful teleportation

teleportation

modified 2 days ago Upstart 976

1

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3

answers

145

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How many classical registers are there on (IBM) quantum computers?

programming qiskit ibm-q-experience

modified 2 days ago Kim Dong 251

2

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3

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206

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How can we construct a square root of NOT gate in Qiskit and IBMQ circuit composer using universal gates?

quantum-gate qiskit programming

modified 2 days ago Aleksey Zhuravlev 25

2

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3

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136

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What's the purpose of phases in quantum mechanics?

quantum-state

modified Jul 11 at 8:37 keisuke.akira 640

2

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0

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35

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Recording Quantum Queries

quantum-information oracles

modified Jul 10 at 19:02 Pratyush Ranjan Tiwari 21

0

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1

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23

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Couldn't connect to IBMQ server: error during login: Expecting value: line 1 column 1 (char 0)?

qiskit

answered Jul 10 at 12:59 jyu00 31

-1

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2

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77

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Nielsen and Chuang: Demonstration of equation 2.12

nielsen-and-chuang matrix-representation textbook-and-exercises

modified Jul 10 at 11:12 user12984287 502

2

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1

answer

177

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Couldn't connect to IBMQ server

programming qiskit ibm-q-experience

modified Jul 10 at 6:22 长风剑哥 9

5

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2

answers

96

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Representation of rotation operators $e^{-i\theta(I-Z_1\otimes Z_2 \otimes Z_3)}$ about arbitrary axis for $3$ qubits

qiskit programming circuit-construction hamiltonian-simulation matrix-representation

modified Jul 9 at 22:37 Dan Strano 31

4

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1

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117

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Use Qiskit in other programming languages (C#, JavaScript and Lua)

qiskit

modified Jul 9 at 19:03 Community♦ 1

0

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2

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278

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Problems with Q# installing

q#

modified Jul 9 at 18:05 Community♦ 1

0

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1

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41

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Feedback on Deutsch-Josza alg. homework prob. in Learning Quantum computation using Qiskit [closed]

qiskit

answered Jul 9 at 15:41 Lena 191

2

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3

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126

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Is it possible to mine bitcoin by implementing Grover's algorithm on a quantum computer

grovers-algorithm

answered Jul 9 at 15:40 Sam Jaques 699

0

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2

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70

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Does anyone know how to get a list of all the Qiskit ML datasets, and if they can also be used for classical machine learning?

qiskit machine-learning

modified Jul 9 at 14:06 Community♦ 1

0

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2

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41

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Are there any resources of lists of attempts at non-probabilistic models of quantum mechanics, with debunking?

quantum-state resource-request

answered Jul 9 at 4:33 kludg 2,210

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