Questions tagged [programming]

For any questions whose answer is expected to require code or programming notions. For questions about a specific framework (e.g. qiskit or cirq) please also include a more specific tag.

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2
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1answer
264 views

Print circuit compiled on hardware?

I would like to see the compiled circuit as executed on a hardware. Nominally, this sequence of commands should return the QASM circuit in the variable ran_qc, but ...
3
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2answers
813 views

How to fix? 'E1101:Instance of 'QuantumCircuit' has no 'h' member' and 'E1101:Instance of 'QuantumCircuit' has no 'cx' member'

I'm using this simple code to test my Qiskit and learn how to use it but it keeps giving this problems, how do I fix it (Using VS Code and Anaconda Python 3.7) ...
2
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1answer
917 views

qiskit - Is there any way to discard the results of a measurement?

I have a circuit composed by n qubits, plus a single one which is an ancilla. I'm making multiple measurements on the ancilla at different stages of the circuit, ...
3
votes
1answer
813 views

Is it possible to expand/merge different circuits?

Suppose I have created a circuit composed of some registers with the usual qc = QuantumCircuit(qr, cr) where qr and ...
3
votes
1answer
430 views

How to set up Qconfig.py and where is the file?

How to set up Qconfig.py and where is the file? I mean under which folder? Like /anaconda/lib/python3.6/site-packages/qiskit/.
3
votes
2answers
331 views

Implementing gate with two parameters using Qiskit in Python

I am trying to implement the HHL algorithm (for solving $Ax=b$). I am assuming $A$ to be unitary and Hermitian so that I can find the Hamiltonian simulation for it easily. For any $A$ to be Hermitian ...
2
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1answer
126 views

An algorithm with the Hadamard operator

My goal in writing this algorithm in Q# was that func would either output (1,2) or (10,20), ...
6
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2answers
924 views

Measuring the Hamiltonian in the VQE

I am trying to implement VQE in pyQuil and am dumbfounded by how to measure the expectation value of a general Hamiltonian on $\mathbb{C}^{2^n}$ i.e. determine $\langle\psi , H \psi\rangle$ on a ...
1
vote
2answers
276 views

Is it possible to create controlled gates with an exponent in Cirq?

Is it possible to create controlled gates with an exponent in Cirq? For example, a controlled $\sqrt Z$ gate.
6
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2answers
393 views

Quantum counting in Q#

I cannot seem to get an estimate for the number of solutions using the quantum counting algorithm described in Nielsen and Chuang, i.e. phase estimation with the Grover iteration acting as $U$. I try ...
2
votes
2answers
178 views

Why do $n$ inputs to a ket give a vector of dimension $(2^n,1)$?

NB - notation from Octave. I understand that ket([0]) is the $(1,0)$ in a $(x,y)$ plane. But when I try a ket with three numbers I get a column vector of dimension $(8,1)$. I assume that comes ...
2
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1answer
168 views

Are there any test examples of Octave and Quantum Entanglement?

I read this research paper. I have octave and the package running. This is an example of what I did so far - octave:3> s1 = state(normalize(ket([1,0])+ket([0,1]))) s1 = 0.00000 0.00000 0....
7
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0answers
79 views

Is it better to use fewer gates or fewer working qubits? [closed]

I have a script that takes a while to simulate. I can modify it in such a way where I can use fewer qubits at a time, but it will require more iterations of manipulation. I believe this will cut down ...
3
votes
1answer
970 views

Practical example of Grover's algorithm (in Q#)

Is there any real example for Grover's algorithm but with real database (generated from SQL or file)? I download the Q# development kit & its example, there was one call DatabaseSearchExample ...
8
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2answers
710 views

Qubits specification on IBMQ devices

As it is shown here, CNOT gates between different qubits have different error rates. I have the following questions: 1) While defining a circuit on QISkit, does ...
1
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2answers
189 views

How can the state $\lvert0\rangle+M^{-1/2}\sum_{j=1}^M\lvert j\rangle$ be generated?

I was wondering if anybody to help me to generate the following state. It would be preferable if you use only Hadamard, CNOT and T-gates, on $\lceil\log_2(M+1)\rceil$ qubits: $$|\psi\rangle = \frac{1}{...
2
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1answer
2k views

Q# How to use a namespace in another project?

I have some utility operations that I'd like to use across projects. How can I import its namespace using Q# in Visual Studio 2017 in other projects?
2
votes
1answer
74 views

How to compute the tensor product in QCL?

When I look at QCL (the documentation of the language begins in chapter 3) I don't see a way to compute the tensor product between two q-bits. Is the programming operator ...
3
votes
3answers
567 views

How to run algorithms on IBMQ via Qiskit-Aqua?

I am trying to run an optimization problem on IBMQ. Running the same code on QASM simulator works fine. However, changing only the backend name to IBMQX takes long time. I am aware of the queues ...
2
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0answers
525 views

Qiskit SDK problem [closed]

So I am getting this error when I fire the command on Ipython or Jupyter Notebook ...
2
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1answer
457 views

How to make "random U3" in QASM?

I want to make an operator: $\mathrm{U3}(\arccos(\sqrt p),0,0)$, when $p$ is a random value between $0$ and $1$ How do I write code in QASM language of this "random $\mathrm{U3}$" operator?
3
votes
0answers
554 views

Qiskit Python program cannot connect to QE API

I am just getting started with Qiskit and IBM Quantum Experience, so please forgive my newby question. I have a IBM Quantum Experience account and I generated an API token. I used the generated ...
1
vote
2answers
2k views

How do I construct a Density Matrix corresponding to a Hamiltonian?

I have a Hamiltonian and I want to know the corresponding density matrix. The matrix I'm interested in is the one in this question.
5
votes
1answer
197 views

Flying qubits compared with stationary qubits

In a previous question I asked how stationary bits could be processed by logic gates. I casually mentioned that I could visualize qubits traversing stationary logic gates, and @DaftWullie said “It ...
3
votes
1answer
200 views

How can I resolve the error QISkit Error: The same provider has already been registered!

I am writing a small algorithm to multiply two numbers using IBM's QISkit. The code is below: times_shell.py ...
3
votes
3answers
194 views

How can I get the qiskit module

I have successfully installed qiskit. However, when I try to run a simulation I get the error "No module named 'qiskit' ...
3
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2answers
122 views

Where is the problem stored in a quantum computer?

I am trying to develop a more intuitive understanding of quantum computing -- I suppose Feynman would tell me that’s impossible! Let’s try: if we are trying to find the minimum of a surface or ...
6
votes
1answer
2k views

How would one implement a quantum equivalent of a while loop in IBM QISkit?

I'm writing a simple multiplication algorithm that uses the Quantum Fourier Transform to repetitively add a number (the multiplicand) to itself and decrements another number (the multiplier). The ...
7
votes
2answers
996 views

How to construct the "Inversion About the Mean" operator?

It seems like it should be simple, based on how Nielsen and Chuang talk about it, but I cannot seem to correctly implement the Inversion About the Mean operator ($2|\psi\rangle \langle\psi| - \mathcal{...
3
votes
1answer
380 views

Confusion over tensor products in sympy.physics.quantum.qubit (in Python)

I am working with sympy.physics.quantum.qubit to help teach myself more about quantum computing. I'm confused about how best to simplify two ket expressions that ...
2
votes
1answer
231 views

How to add two integers in Q#?

I have programmed in C++, but I am interested in writing quantum programs. I have some experience with Microsoft's Q#, and I know about the canonical Shor's and Grover's algorithms. Can anyone tell ...
3
votes
1answer
1k views

How to measure in an arbitrary basis in Q#?

Q# has a measurement operator defined as follows according to the docs: operation Measure (bases : Pauli[], qubits : Qubit[]) : Result Where you give a Pauli gate ...
4
votes
1answer
214 views

How to deal with -LookupError: backend "ibmqx4" is not found?

I am using Jupyter notebook to write and running my qiskit codes (python 3.6) and every time I encounter the message: LookupError: backend "ibmqx4" is not found, right now the ibmqx4 computer is not ...
4
votes
1answer
900 views

How to install qiskit in spyder editor?

I am working in Anaconda using spyder editor. Can anyone tell me how to install qiskit in spyder?
13
votes
3answers
423 views

Which programming language is suitable for a beginner?

I understand there are a lot of programming languages (e.g. Q#, Qiskit, etc.) Which one is suitable for someone that just started learning programming and doesn't know anything about quantum ...
8
votes
2answers
189 views

How does one obtain amplitude information in Q#?

Is it possible to obtain amplitude information (in lexicographic ordering) for a particular qubit register in Q#? For example, in the following code: ...
13
votes
2answers
1k views

Automatic compilation of quantum circuits

A recent question here asked how to compile the 4-qubit gate CCCZ (controlled-controlled-controlled-Z) into simple 1-qubit and 2-qubit gates, and the only answer given so far requires 63 gates! The ...
5
votes
2answers
545 views

Finding the maximum number of Q# simulatable qubits

I'm new to Q# and I was curious on how one would find the number of Q# simulatable qubits for a specific machine. I know Microsoft has an approximation of 16GB ~ 30 qubits but I wanted a better ...
5
votes
1answer
187 views

Q# factorization Method Program

Is there a method to calculate prime factorization in Q# of Visual Studio of Microsoft Quantum Development Kit? In the Python language, it is the sympy.factorint ...
6
votes
2answers
489 views

How do we code the matrix for a controlled operation knowing the control qubit, the target qubit and the $2\times 2$ unitary?

Having n qubits, I want to have the unitary described a controlled operation. Say for example you get as input a unitary, an index for a controlled qubit and another for a target. How would you code ...
8
votes
2answers
201 views

Can we perform quantum mechanical simulations using a quantum computer?

I'm a computer science major who's really keen on physics and quantum mechanics. I have started learning about Q# and D-Wave, but I just wanted to know if it's possible to test quantum mechanical ...
8
votes
2answers
2k views

Possibility of a "reset" quantum gate

I wish to have a "reset" gate. This gate would have an effect to bring a qubit to the $\mid0\rangle$ state. Clearly, such a gate is not unitary (and so I'm unable to find any reliable implementation ...
4
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3answers
2k views

Comparing run times on IBM Quantum Experience

I have run this program - ...
13
votes
2answers
398 views

Hamiltonian simulation with complex coefficients

As part of a variational algorithm, I would like to construct a quantum circuit (ideally with pyQuil) that simulates a Hamiltonian of the form: $H = 0.3 \cdot Z_3Z_4 + 0.12\cdot Z_1Z_3 + [...] + - ...
5
votes
1answer
466 views

List of qubit locations with cirq

As far I understand, qubits in cirq are labelled by their positions on chip. For example print( cirq.google.Foxtail.qubits ) yields ...
7
votes
3answers
419 views

Is there something like GitHub for quantum programming?

I'm just learning about quantum computer but some of it has been available for people to research & practice so I'd like to study it myself. The only kind of quantum computing I found so far is ...
7
votes
1answer
828 views

What is the purpose of the TDG gate in QISKit?

The QISKIT documentation doesn't explain what a TDG gate does and I can't find it anywhere else online.
5
votes
1answer
316 views

Quantum SVM Algorithm Error on import

I am experimenting with some Qiskit ACQUA AI algorithms which require the following import statement: from datasets import * However, ...
5
votes
1answer
475 views

Is there a common set of modules for user-defining-quantum-gate for QISKit

I am wondering if there exists a common library or a set of modules for user-defining-quantum-gate for QISKit. If it does, could you tell me? By referring to Define Quantum Gates and How to define ...
23
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4answers
4k views

Are quantum computers just a variant on Analog computers of the 50's & 60's that many have never seen nor used?

In the recent Question "Is Quantum Computing just Pie in the Sky" there are many responses regarding the improvements in quantum capabilities, however all are focussed on the current 'digital' ...