Questions tagged [ibm-q-experience]

Use this tag for questions about IBM's Quantum Service - Circuit Composer & Quantum Lab. DO NOT use this for questions about general Qiskit issues. As of August 2020, there are 20 processors on the IBM Q Experience ranging from 5 to 53-qubits. Note: Some systems are only available to hubs, partners, and members of the IBM Q network.

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IBMQ / Qiskit slack links are broken [closed]

It appears the Slack links to IBMQ slack pages are broken (The link is no longer active). This is case for links on both Qiskit and IBMQ support pages. What is the best way to gain access to the Slack ...
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VQE jobs do not appear in queue

I am trying to calculate the ground state energy of some simple molecules using 'MolecularGroundStateEnergy' tools in qiskit. When I run the calculations for very small molecules (e.g. H2, HeH+) the ...
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How to remove ancilla bits from results?

I have a circuit with 2 ancilla bits. I have only asked that the circuit measure the 4 other qubits, but the results keep including the ancilla bits. How to remove the ancilla bits from the results?
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How do you turn the CX gate upside down on ibm-q-experience?

I am learning how to make Grover's algorithm but the last cx gate needs to be the opposite way around. It always makes the top qubit the control, so how do you turn it around?
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Why after transpiling a Qiskit circuit we obtain a different result?

I am trying to obtain the correct circuit transpiled for the ibmq_london device, as I want to know what the real gates applied in the quantum computer are. I am implementing the QFT circuit for 5 ...
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What extra functionality is available to an IBM Q Network member over a regular IBM Q Experience user

I've been trying to figure out the extra functionality available to IBM Q Network members that are not available to normal ...
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Question About How Qiskit Reset Gate Affects Other Entangled Qubits

I am trying to understand how the reset gate in Qiskit affects qubits its entangled with. Consider the following circuit with qubits $q_0$ and $q_1$: Where circuit240 takes $|0\rangle$ to $a|0\rangle ...
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72 views

What is the difference between Qiskit execute and the IBMQJobManager?

I was researching how to submit multiple pulse schedules/circuits in the same job and came across 2 methods: Executing Experiments with qiskit.execute and ...
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Why are IBM QE backend results different from the qasm simulator for a simple quantum circuit?

I have looked at other questions that ask pretty much the same thing such as this and from what I gathered the significant difference in simulation and actual results is due to decoherence and ...
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How to do error mitigation on the ibmq_16_melbourne?

I'm trying to make a calibration matrix using CompleteMeasFitter as in here on IBMQ Melbourne, but I need to use all 15 qubits, which mean it has to run 32768 calibration circuit, far exceeding the 75 ...
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Post-selection in QASM

In some quantum algorithms (for example HHL or quantum machine learning algorithms) an ancilla qubit(s) is measured firstly and based on result of the measurement other qubit(s) are measured or not. ...
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Why is the number of solutions given in Qiskit textbook(Quantum Counting Algorithm) as N-M instead of M?

I'm following the Qiskit textbook for Quantum Counting. We have assumed $M$ as the number of states containing solutions throughout the algorithm but at last, $N-M$ has been taken as the solution. ...
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Time taken on IBM Q qasm_simulator vs real backend

Running the same quantum circuit (example picture below, I've tried similar circuits too), both on a simulator and real backend, I've found than the simulator is always faster (sometimes by order of ...
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Problem with comments and code rearranging in IBM Q web interface

I wrote some code in QASM in the IBM Q Experience web interface and then I added some comments. After that I saved the code and run it. However, the code was rearranged (for example some gates were ...
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60 views

Quantum error correction on IBM devices?

I'm wondering if the gate errors on any of the IBM devices are low enough so that we could use some error correcting codes which do not require too many qubits? (such as 5- or 7-qubit codes). Even ...
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How can I install the 'ibmq_qasm_simulator' backend?

I'm having trouble running the following cell: The system told me "The 'ibmq_qasm_simulator' backend is not installed in your system." I'm so confused. Is there a way I can install this backend in my ...
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Do all physical architectures for quantum computers use the same universal gate sets?

Now I have understood that physical implementation of quantum computer need a universal quantum gate set like Clifford+T to realize any unitary quantum gate. However, I don't know if it is all the ...
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How to stop optimization of a circuit during transpiling in web-interface of IBM Q?

I was playing with approximation of gates with Clifford+T group on IBM Q. Everything works well on simulator, however, when I tried to run my circuit on actual quantum processor, a transpiler ...
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Who cares about Transpiled Circuit Text? [duplicate]

At any result of a job in this last version of the Circuit Composer, at the OpenQasm tab inside the Circuit Diagram, I am unable to use the tradicional copy or ctrl-c to get the transpiled circuit ...
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How to not optimize the quantum gates in a qiskit circuit when running it in the real device?

I have been trying to run two circuits in the ibmq_london device, the one resulting of applying one X gate on qubit $0$ and the one that applies two X gates. I know that applying two X gates is the ...
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Grover oracle result: vectors (0,1) & (0,1) => two Hadamards => product of two H results => CZ = (.5, .-5, -.5, -.5)

According to the Grover's algorithm section in the IBM Quantum Experience, if I have two qubits in the "one" state (vectors (0,1) and (0,1)), and I apply a Hadamard gate to each of them, and then ...
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Names of IBM Q backends

IBM Q backends have many different names, see for example this link. We have for example processors called Melbourne, Tokyo, Armonk etc. I am curious where these names come from? For example, I know ...
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Problem with code in 'Learning quantum computation using qiskit

I've started learning quantum computing using 'Learn quantum computation using qiskit', and I've stumbled upon what I think is a bug in the code in chapter 1.3: Representing Qubit States when I ...
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IBM Q Experience - Can it be used draw out ML inferences? [closed]

Are there Quantum-enhanced Machine Learning algorithms that can be implemented via Qiskit in IBM Q Experience and obtain valuable inferences faster than their classical counterparts from datasets of ...
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Install qiskit in django project

I was wondering if it's possible to use qiskit inside a django project. I found some ways to install jupyter notebooks, but I am not sure what is happening with qiskit. Ideally I would like to import ...
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How to obtain the density matrix using tomography in the real device?

I am trying to run the QFT algorithm for n=5 (n number of qubits). The number of experiments that it generates is bigger than the one allowed by the IBM devices (i.e. 75). Therefore, I have tried to ...
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Moore's law for quantum computers

Moore's law states that performance of classical computers doubles every two years (later revised to 18 months) and a price for computing resources halves during same time period. Currently, it seems ...
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28 views

Conversion of python code on Machine learning to realise on quantum processor

I need to realise a Python code program on Qiskit. It works on fuzzy logic. How should I realise the same using quantum processors using Qiskit? Is there any support on realising Python code for Fuzzy ...
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How do IBM, D-Wave, etc. change phase physically?

How do IBM, D-Wave, etc. change phase physically? In real hardware?
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IBMQfactory._initialize_providers Error

After a successful first run without problems, I found that I cannot connect any longer. Code: ...
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How to get running time for each circuit executed on IBM's quantum processors in one round?

I want to execute multiple circuits in one round on IBM's backends, especially the 16-qubit one, to save time. For instance, ...
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Is it possible to build a quantum processor with connections among all qubits?

Current quantum processors have constrained connectivity among qubits. For example Starmon-5 processor by Quantum Inspire has only one qubit connected to others, effectively it looks like a star. The ...
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60 views

How to reduce unnecessary waiting time when using IBM's backend?

I'm working with a program, which needs iterations of quantum computation like this ...
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ibmq_qasm_simulator from IBMQ provider and qasm_simulator from Aer provider gives different results

I'm running an experiment first on qasm_simulator backend from Aer provider and the most frequent result is the correct one with ...
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Do I have to upgrade to personal computer or laptop computer in order to be able to use the IBM Quantum Experience website or run code locally?

I currently have a tablet I don't have a desktop or laptop to access the IBM Quantum Experience. Do I have to upgrade to personal computer or laptop computer in order to be able to use the website or ...
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How to write decent code for oracle in Qiskit without custom circuit or long truth table?

I am now practising using Qiskit. The example of Grover's algorithm in tutorials suggests using logical expression, truth table or circuit to construct the oracle. In most textbooks on quantum ...
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How can I find the most suitable IBMQ provider for my location? [duplicate]

I have been trying to run my code on IBM's quantum computers, so I used the following commands to associate a quantum computer to the component qcomp: ...
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Trying to get a provider from IBMQ but get 'No provider matches the criteria.'

I have created a circuit and then run the following: provider = IBMQ.get_provider('ibm-q') And this is what I get: ...
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1answer
183 views

ModuleNotFoundError: No module named 'qiskit.circuit.library'

I am importing from qiskit.circuit.library import MCMTVChain on python IDLE editor but it showing error ...
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1answer
178 views

How to make circuit for n-control Z gate( i.e $C^3Z$ )?

I am trying to make circuit for $C^3Z$ gate I have seen a circuit for $C^2Z$ or $CCZ$ gate made by using $CCX$ gate so is there any way to make circuit for $C^3Z$ in this similar manner( i.e by using $...
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Why is a different convention used for the $Rz$ implementation on IBM Q?

A $z$ rotation gate is defined as $$ Rz(\theta)=\mathrm{e}^{-i\frac{\theta}{2}Z}= \begin{pmatrix} \mathrm{e}^{-i\frac{\theta}{2}} & 0 \\ 0 & \mathrm{e}^{i\frac{\theta}{2}} \end{pmatrix}, $$ ...
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63 views

Quantum gates execution times on IBM Q Melbourne

I am interested in the execution time of quantum gates on IBM's $15$-qubits Melbourne computer. Is there any information regarding this? After searching for a while I have only managed to find the ...
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Access IBM Q processors from MatLab

Qiskit allows a user to directly access IBM Q quantum processors (both real ones and simulator). Each user is given a personal code which is entered into source code and serves as a login to the IBM Q ...
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What is the best IBMQ provider to South America?

What is the best option for South America Brazil to configure: provider.get_backend (''), because melbourne_16 is very slow.
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Is there an archive of IBMQ calibration data?

Specifically, I'd like to see the ibmq_london calibration file for April 15, 2020.
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What are examples of quantum computing platforms availble for free (other than IBM Q)?

IBM Q is (maybe first) quantum computing platform allowing users to register for free and run algorithm on real quantum processors. There are several processors with usually 5 qubits, however, it is ...
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Transpiling error in IBM Quantum Experience

I ran the following code which adds two 2-digit numbers on different back-ends and the simulator gives the expect result while all real QC's have a problem with the transpiling: In fact, Melbourne ...
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2answers
84 views

Readout error in IBM quantum experience processor

Is there a section on the IBM website that shows information about the readout error for the devices of quantum experience? I have only seen the errors for single-qubit (U2) and CNOT gates but nothing ...
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Tensor product IBM on Quantum Experience

How can you take the Tensor Product in IBM Quantum Experience? For example $$(X|1⟩) \otimes ((X|1⟩)$$ I have tried to look up but couldn’t find anything
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Qiskit flipped representation of qubits in CNOT gate?

The conventional CNOT gate is shown on the right, and the Qiskit version is on the left. Since Qiskit defines it has a flipped representation kindly explain what is happening to the 11 position?

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