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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1answer
94 views

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
191 views

Error while running the circuit on a real device on IBMQ

I have been trying to run a circuit on 'ibmq_16_melbourne'. But the result shows ERROR_RUNNING_JOB. The run status says: ...
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1answer
55 views

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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1answer
43 views

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
49 views

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
60 views

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
30 views

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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2answers
63 views

Bernstein-Vazirani IBMQ error due to probably measurements

I'm using the following piece of python code: ...
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1answer
123 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
52 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
78 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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72 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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2answers
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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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38 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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46 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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1answer
30 views

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
109 views

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
85 views

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
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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
486 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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2answers
147 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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0answers
45 views

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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3answers
156 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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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
132 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
147 views

Different QFT results when using Simulator or Quantum Machine

I'm performing QFT using the following code: ...
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1answer
39 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
214 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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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
272 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
79 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
83 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
2k 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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1answer
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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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43 views

How can I find the fidelity of preparation?

I want to know the fidelity (or error rate) of the preparation ($|0\rangle$) How can I have it?
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1answer
89 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
202 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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1answer
111 views

IBMQ: `from qiskit import QISKitError` gives 'cannot import name QISKitError'

When I run: from qiskit import QISKitError I get the error: ImportError: cannot import name 'QISKitError' I need ...
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1answer
101 views

Can we add two classical registers in IBM Quantum Experience?

Suppose I have 01 and 11 in classical register 1 and 2 respectively in IBM quantum experience circuit. I want 01 + 11 = 00 mod 4. Can it be done?
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Difficulty in implementing Grover's Algorithm with large number of qubits

It seems IBM offers a 15 qubit quantum computer through their quantum experience program. However, upon a quick search through the literature, the largest implementation of Grover's algorithm I have ...
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2answers
269 views

Why IBM Quantum Experience is giving different results under ibmq_qasm_simulator and ibmq_16_melbourne?

I am trying to run following 6 qubit quantum circuit and I am getting different results under ibmq_qasm_simulator and ibmq_16_melbourne (both involving 8192 shots). What is the reason? ...
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2answers
88 views

Can we capture phase in IBM Quantum Experience?

I have a sample IBM experience circuit which generates $$\frac{1}{2}(|00\rangle - |01\rangle - |10\rangle + |11\rangle)$$ When we measure the state will be either $|00\rangle$/$|01\rangle$/$|10\...
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1answer
676 views

Superdense coding circuit returns wrong result

I'm new to quantum computing, but everything I've read about superdense coding claims that, in the circuit below, Bob should receive a $[01\rangle$ from Alice. Unfortunately, that's not what I get ...
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1answer
73 views

What is the source of this TranspilerError when running qasm file?

I want to run this qasm file using IBM device. However, there's always an error: ...
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2answers
214 views

How to construct a IBM Quantum Experience circuit for the following state transformation?

Please help me in building IBM Quantum Experience circuit for: $$ M|0\rangle = \frac{1}{2}(|0\rangle+|1\rangle+|2\rangle+|3\rangle) $$ Edit: Is it possible to make a circuit for a general ...
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1answer
224 views

Simpler implementation of the Toffoli gate on IBM Q for special circumstances

On current quantum hardware, a depth of circuit is constrained because of noise. In some cases, results are totally decoherent and as a result meaningless. This is especially true when Toffoli gates ...
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1answer
289 views

How to run the Qiskit Aer simulator without noise?

I know that the Qasm Simulator execute quantum circuits with presence of noise, even if I do not specify the model of noise in options for that backend. But how can I execute the circuits without ...
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1answer
110 views

When increase the shot, why the result is different?

when I measure the shot = 1024 when I measure the shot = 8192 I want to derive result value 011(=3) However, I know if measure the more shots, increase the accuracy. why this result derive??? why ...
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1answer
99 views

How to set initial state on IBM Q?

For my undergraduate final project I am working on a Quantum Inspired Genetic Algorithm. For this I am using IBM Q real devices and I need to set a custom initial state on qubits. Using the ...

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