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1500 questions
9
votes
2 answers
Are we certain that quantum computers are more efficient than classical computers can be built?
I mean are we certain that they will be able to provide us a huge improvements (in some tasks) compared to clasical computers?
Adou
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9
votes
1 answer
Prove that adding any non Clifford gate to the Clifford group yields a universal gate set
I have seen it claimed in multiple places that adding any non Clifford gate to the Clifford group yields a universal gate set. It is, however, not easy to find an accessible proof of this fact.
The…
Ian Gershon Teixeira
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9
votes
2 answers
Calculate the period (like in Shor's algorithm) from the factors?
One of the fundamental elements of Shor's algorithm is the calculation of the function:
$$
f_a(r) = a^r (mod \ N)
$$
where $N$ is the number to be factored and $a$ is a number chosen with some limitation. The quantum circuit is able to find the…
Doriano Brogioli
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9
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1 answer
Is the controlled-Hadamard gate in the Clifford group?
Is the controlled-Hadamard gate a member of the Clifford group? I understand that Controlled Pauli gates are in the Clifford group.
If controlled Hadamard is Clifford member, then is a controlled-SingleClifford also a member of the Clifford group ?
Isolated Information
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What are the differences between Qiskit's AerSimulator, QasmSimulator and StatevectorSimulator?
In Qiskit, we can see the names of available simulators with the command Aer.backends(). These include:
AerSimulator('aer_simulator')
AerSimulator('aer_simulator_statevector')
AerSimulator('aer_simulator_density_matrix')…
user3886914
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9
votes
1 answer
Is it possible to speed up the generation of the weighting matrix using a quantum algorithm?
In this[1] paper, on page 2, they mention that they are generating the weighting matrix as follows:
$$W = \frac{1}{Md}[\sum_{m=1}^{m=M} \mathbf{x}^{(m)}\left(\mathbf{x}^{(m)}\right)^{T}] - \frac{\Bbb I_d}{d}$$
where $\mathbf{x}^{(m)}$'s are the…
Sanchayan Dutta
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9
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2 answers
How to implement Projector Control-Not in Qiskit?
I want to impliment Projector Control-Not in Qiskit just like in this , which is a $|0\rangle\langle 0|$ projector found in the paper "Grand Unification of Quantum Algorithm" page 7. Also, is the angle $\phi$ and the exp same as the parameter of…
Shashi Kumar
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9
votes
1 answer
Can quantum annealing find excited states?
If we start with a Hamiltonian $H(t_i)$, and with our qubits prepared in the ground state of this, and then slowly change this to a Hamiltonian $H(t_i)$, the final state of our qubits should be the ground state of the new Hamiltonian. This is due to…
James Wootton
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9
votes
1 answer
What is the applicability of quantum network coding?
As the title suggests, I want to know what the applicability of quantum network coding is, besides the EPR pair construction between distant pairs of 'Users-Targets'.
Can quantum network coding be used for computation?
Ivanovitch
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9
votes
2 answers
Measuring in standard basis meaning
What does it mean to measure a qubit (or multiple qubits) in standard basis?
Archil Zhvania
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9
votes
3 answers
How to implement the "Square root of Swap gate" on the IBM Q (composer)?
I would like to simulate a quantum algorithm where one of the steps is "Square root of Swap gate" between 2 qubits.
How can I implement this step using the IBM composer?
JanVdA
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9
votes
1 answer
Where can I find example circuits to learn from?
I'm relatively new to quantum computing and my goal is to learn how to implement algorithms that I read in papers. While I have found many circuit snippets I have yet to find a repository of examples on GitHub or other places where I would go to…
ChrisBartlett
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9
votes
1 answer
Can a quantum computer tell whether a program is Turing complete?
I am very new to quantum computing and would like to know if a quantum computer can decide whether a given program is Turing complete.
Laith Striegher
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9
votes
2 answers
Allowed CNOT gates for IBM Q 5 quantum computer
I trying to do some tests in the IBM Q5 computer of IBM quantm experience for some simple error correction protocols, but as I can see, some operations between the qubits are not allowed.
For example, it is not possible to perform a CNOT operation…
Josu Etxezarreta Martinez
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Can we use quantum phase estimation to learn anything about the dynamics of puzzles like the Rubik's cube?
Introduction
Consider a state $\vert\psi\rangle$ such as below, which is in a superposition of a difference between a Rubik's cube in a solved state and a Rubik's cube in the "superflip" state.
Here, with eight cells on each face (apart from the…
Mark Spinelli
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