Questions tagged [ibm-q-experience]

Use this tag for questions about IBM's quantum processors which are accessible online. DO NOT use this for questions about general Qiskit issues. As of July 2018, there are five processors on the IBM Q Experience: two 5-qubit processors, one 16-qubit processor and two 20-qubit processors (only available to hubs, partners, and members of the IBM Q network).

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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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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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44 views

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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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
63 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
29 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
52 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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3answers
88 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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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
111 views

Different QFT results when using Simulator or Quantum Machine

I'm performing QFT using the following code: ...
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32 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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78 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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117 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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37 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
46 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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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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321 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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38 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
71 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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136 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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42 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
63 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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152 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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83 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
656 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
63 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
202 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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117 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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180 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
77 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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47 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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1answer
53 views

What is the difference between IBM quantum simulator and others

I am currently doing my final year undegraduate research. For many quantum inspired algorithms are simulated on Matlab. However if I am to run the algorithms on a Quantum Simulator provided by IBM, ...
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1answer
30 views

Are all the IBM QX mapping bidirectional?

The connection between physical qubits of IBM devices are all bidirectional or there are some architectures that there existing some unidirectional connection? I found that in IBM Quantum experience, ...
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90 views

How to run a qasm file on IBMQ device?

I can found many qasm examples. How can I run them on different IBMQ devices?
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1answer
84 views

How to prepare mixed states using IBM quantum experience?

I want to prepare some mixed states regarding a project that I am doing, however, I am not sure how to do that using IBM Q. Experience circuit composer. Basically, I am looking to prepare maximally ...
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81 views

Implementation of tomography on IBM Q

I wanted to ask how do you implement a circuit that finds the non-diagonal values of the density matrix of a quantum state on IBM Q?
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1answer
104 views

What is the $\lambda$ parameter in the $U3$ gate used for?

The most general single qubit gate is $\mathrm{U3}$ given by matrix $$ \mathrm{U3}= \begin{pmatrix} \cos(\theta/2) & -\mathrm{e}^{i\lambda}\sin(\theta/2) \\ \mathrm{e}^{i\phi}\sin(\theta/2) & ...
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104 views

Vey different results between qasm_simulator and quantum computer

I've started playing around with circuits only recently and decided to try out and implement a 4-qubit Grover's search using qiskit. When I run my python script using the qasm_simulator, I get the ...
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140 views

'IBMQFactory' object has no attribute 'load_accounts'

I am following this qiskit workshop from https://colab.research.google.com/github/mtreinish/qiskit-workshop/blob/master/Workshop.ipynb . After adding my API key I had encountered the error ...
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32 views

Problem with circuit composer results tab

I'm trying to run a simulation of the following circuit: on the ibmq_qasm_simulator, but it only shows the "Circuit diagram" without the "Circuit Implementation" and "Results tab". Did someone had ...
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65 views

IBM quantum computers gate delay values

I am doing an state of the art study about the existing quantum computer technologies and one of the parameters of interest is the gate delay value, as it determines the time expected from a gate from ...
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2answers
104 views

Measuring T1 and T2 constants on IBM Q

We have been asked to measure relaxation and dephasing times T1 and T2 on the IBM Q using the composer only, Qiskit not allowed. I am a bit confused about the way to do so. Can someone explain the ...
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4answers
106 views

Implementing four oracles for the Deutsch Algorithm (preferably on IBM Q Experience)

I guess, I understood simple Deutsch Algorithm (if unary function is balanced or constant) as described here: Introduction to quantum computing: The Deutsch algorithm I need to test it. I was ...
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1answer
134 views

How to make a Shor's algorithm for an arbitrary number of qubits with Qiskit on a IBM machine?

So suppose you want to do a Shor algorithm on an arbitrary number of qubits using an arbitrary $a$ (the base number in the periodic function $a^x \mod c$) and $c$ ( the factored number). Making the ...
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54 views

OPENQASM: How to include my own libraries

I studied the OPENQASM 2.0 spec a few times but failed to find a way to include my own libraries. Have I missed anything? Right now, the only way is to use ...