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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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
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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
650 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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1answer
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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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1answer
75 views

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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1answer
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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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1answer
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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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331 views

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
218 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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1answer
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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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1answer
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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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AssertionError: wrong color format 'ansibrightred'

I am running my old qiskit code after a very long time it's not running now showing error wrong color format 'ansibrightred' and ...
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1answer
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How to get QASM code from IBMQ experience

I am interested in retrieving the OpenQasm code of a quantum circuit, as it appears on IBM Quantum Experience. This is the code that the quantum machine actually runs. I used to be able to just copy ...
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How to control the qubits in IBMQ

I am trying to perform OTOC for my 7 qubit protocol. I need to carefully control and use only 7 qubits but after making measurement in the 16 qubit Melbourne system (ibmq_16_melbourne) my protocol ...
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2answers
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Subroutines on IBM Q (ERROR_RUNNING_JOB returned)

I wrote following code in QASM editor on IBM Q web interface (note ccu1 is controlled-controlled U1 gate): ...
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0answers
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Error when running an algorithm on real device at IBM Q using QASM

I'm running an algorithm on a real quantum device from IBM (ibmqx2), using the QASM and circuit composer, and it just gets the same error over and over again: ...
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0answers
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Meaning of “Running” time field in Results and correlation with the “shots” choosen number

I've created a same circuit that I've executed two different ways on the same computer (ibmq_16_melbourne); First with 1024 Shots and secondly with 8096 Shots For the first (1024), I got in results, ...
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88 views

Bernstein-Vazirani IBMQ error due to probably measurements

I'm using the following piece of python code: ...
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1answer
196 views

Different results between qasm_simulator and quantum computer: how to normalize for only few states

I recently started developing circuits with Qiskit. I made a 5 qubit circuit in which the fourth qubit at the end of execution must always have value 1: When I do the simulation with qasm everything ...
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1answer
60 views

Could someone give an example of this pic?

This is a picture from Wiki(https://en.wikipedia.org/wiki/Quantum_logic_gate). Can someone give me a simple example by using two qubits?
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1answer
167 views

How can I use IF gate in IBM Q composer?

I just want to use the "if" gate in IBM QX circuit composer, but I don't know how.
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146 views

What are the differences between the different transpiler optimization levels in qiskit

I am currently running a simple algorithm using Qiskit and I am running it for various transpiler optimization levels (0-3). I wish to know what exactly occurs differently when for example I run the ...
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Design connectivity of qasm_simulator

About the qasm_simulator, does it have on its 32 qubits a qubit connectivity design like as ibmq_16_melbourne or as another real ...
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42 views

Can't load account on IBM's qiskit

The command load account keeps giving the warning that it can't find a QConfig file. A search for the error message brings me to an answered question. However, this solution also doesn't work, ...
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0answers
48 views

How qubit phase is build in real hardware?

How qubit phase is build in real hardware? On IBM Quantum, D-Wave, etc?
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1answer
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I made a simple circuit on qiskit,but I have some question on this result

I made a simple circuit that we can see. In my view, $|00000\rangle$ should appear in one result, but I didn't see it. why?
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Error parameters from Qiskit backends

In order to build a custom noise model in Qiskit Aer, I requested the error parameters from different backends and got 3 (9) parameters for each single-qubit (two-qubit) gate as output. However, I ...
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2answers
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Gate Y returns wrong phase in IBM's circuit composer

One can check that, with IBM's circuit composer, $Y$ gate acted on $|0\rangle$ or on $|1\rangle$ returns the same phase of $\pi/2$. Is this a bug?
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1answer
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Real backend for my students?

I'd like each of my students to run at least one program (however trivial) on a real quantum computer. They can each sign up for accounts on ibm-q-experience. The question is, which of the backends ...
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1answer
153 views

Why does not ibm-q-experience transpile a circuit always in the same way?

When I run a certain circuit (using several qubits, it is not a very simple one) in IBM quantum experience, I find that sometimes it is transpiled in one way and sometimes in another. And the final ...
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2answers
634 views

Given a state $|\phi\rangle=\frac{1}{\sqrt{2}}(|0\rangle+e^{i\theta}|1\rangle)$, how do I know the angle $\theta$?

Question1. If there is a state $|\phi\rangle=\frac{1}{\sqrt{2}}(|0\rangle+e^{i\theta}|1\rangle)$, and I want to know the angle $\theta$. What kind of measurement should I do? Could somebody give me ...
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273 views

Entanglement Swapping Circuit

I implemented 2 versions of the entanglement swapping circuit in IBM Q. One is using classical measurement to control X, Z gates. Another is just us C-NOT and Controlled-Z. They should be equivalent. ...
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How can I run programs in test folder Github Qiskit

I am new to GitHub/Python - please tell me how can I run programs in https://github.com/Qiskit/qiskit-aqua/tree/master/test and its sub directories in Jupyter. I am connected to IBM Q Expereince. I am ...
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191 views

Error while running Quantum Teleportation Algorithm on real device using qiskit on IBM-Q

I am trying to implement Quantum Teleportation Algorithm on an actual device, I am using IBM-Q Jupyter notebook for the same purpose. The code is as follows: ...
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1answer
322 views

Physical implementation of gates on IBM Q

There is a lot of quantum gates in IBM Q Composer, however, only few are implemented physically while others can be composed of them. When one looks at description of a quantum processor in IBM Q ...
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2answers
157 views

How to implement controlled gate based on measurement (quantum teleportation)?

I am implementing the teleportation algorithm on IBM Q Experience (GUI interface). Certain operations on the third qubit are only performed if the classical measurement result is 1, for example ...
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1answer
156 views

Different QFT results when using Simulator or Quantum Machine

I'm performing QFT using the following code: ...
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1answer
57 views

In Qiskit, where is the floating point operation performed?

I am using Qiskit - the simple circuits I am writing can either run on the hardware backend (using least_busy) or the QASM simulator backend. If I have statements like the following - (...
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2answers
294 views

Mitigating the noise in a quantum circuit

I'm using Qiskit and I have a Quantum Circuit (say, circuit) that gives reasonable results when using the simulator, namely ...
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0answers
34 views

How many cores and what processors are used in the cloud ibmq_qasm_simulator?

Cloud IBMQ simulator ibmq_qasm_simulator can process up to 32-qubit circuits quite fast. However, I could not find any information about the simulator backend properties, e.g. how many cores, what ...
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1answer
388 views

How many Qubits does the qiskit implementation of Shor's Algorithm need to factor N=15?

I know there is a documentation for qiskit.aqua.algorithms.Shor that explains that they used this reference for implementing the actual circuit. It says that the number of qubit needed is 2n+3. So to ...
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1answer
107 views

IBM Q calibration parameters

If I download calibration of a quantum processor on IBM Q website I see these parameters: T1 T2 frequency (GHz) readout error single qubit U2 error rate CNOT error rate T1 and T2 are relaxation and ...
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1answer
117 views

Are $\mathrm{cRz}$ with angle $\pi$ and $\mathrm{cZ}$ equal on the IBM Quantum Experience?

I was trying to implement the 2-qubit Grover algorithm without the auxiliary bit. Before finding the gate symbol for the controlled $\mathrm{Z}$, I worked with the controlled $\mathrm{Rz}$. The gate ...
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1answer
3k views

Which subatomic particle does each company use in quantum computing?

Probably each company (Google, Amazon, Intel, IBM, Microsoft, D-Wave and so on) uses a mix of subatomic particles and technologies. I would like to know which particles/technologies are used by each ...
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389 views

How can I get the entire histogram in a 5 qubit program done in IBM quantum experience machine?

I have run a program on an IBM quantum experience machine which involves 5 qubits. Obviously when I measure the whole system I have 32 results but the machine only represents 20 in the histogram. In ...
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1answer
88 views

How can I find the fidelity of preparation?

I want to know the fidelity (or error rate) of the preparation of $|0\rangle$. How can I obtain it?
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1answer
96 views

Why I am not getting approximate equiprobable states in the following circuit on IBM Q simulator?

I have the following circuit which consists of symmetric modules. I compiled the circuit in IBM Quantum experience backend - ibmq_qasm_simulator, 8192 shots. The result is not equiprobable. Why? Since ...
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1answer
248 views

Why I am getting transpilation error while executing the following IBM Quantum Experience code?

While executing the following circuit (consisting 16 qubit and 4 classical bits) I am getting "Error in transpilation process. [1003]" error. I have a group of 2 operations (you can observe circuit ...

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