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 (use [qiskit] for that).

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Error with IBM's Quantum Composer Qiskit Histogram when Resets are involved?

I am having trouble understanding what IBM's histogram is doing. I have independently verified, in agreement with the statevector given from IBM, that after all these steps the statevector should be ...
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1 vote
2 answers
576 views

How can I save IBM Quantum API token to local environment?

I have an IBM Quantum account. How can I save the IBM Quantum API token to local environment so that I can access services including real quantum systems, simulators and Qiskit Runtime programs on my ...
2 votes
1 answer
638 views

How can I retrieve Qiskit Runtime jobs that I have submitted to IBM Quantum?

I have submitted Qiskit Runtime jobs. How can I retrieve the old jobs to check the status and results?
2 votes
1 answer
348 views

How to construct a Hamiltonian containing Pauli string by qiskit?

There is a Hamiltonian I want to construct by a Python package, which is the following: $$ H = 5.9I + 0.21Z_0 - 6.12 Z_1 - 2.14(X_0X_1 + Y_0Y_1) + 9.6(I-Z_2) - 3.9(X_1X_2 + Y_1Y_2) $$ It is very easy ...
2 votes
2 answers
97 views

Platform for mixed-state quantum machine learning?

I have been using PennyLane to run numerical QML simulations but it now seems to only support backprop on pure state simulations. Does anyone familiar with other packages know if there exists one that ...
1 vote
1 answer
50 views

What happens to the elements of the simulated state vector when we set a qubit to $|0\rangle$?

In IBM's Qiskit online simulator, we have the (non-reversible) ability to set a specific qubit to $| 0\rangle$. This is convenient but I'm left confused as to what happens to the elements of the ...
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3 votes
0 answers
66 views

Incorrect probabilities in IBMQ Mid-circuit measurements

I calculated the probabilities for two measurements using mid-circuit measurements feature in IBMQ by following circuit: ...
3 votes
1 answer
129 views

Bias in the results of superposition measurements on IBMQ Backends, qiskit

Dear people on this forum, I was doing some research, and I created this circuit in qiskit Please bear in mind that I am really new to this field, and I do not retain much knowledge yet. Therefore I ...
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0 votes
2 answers
223 views

Given this code fragment, what is the probability that a measurement would result in $|0\rangle$?

Trying to understand below probability how it occured? qc = QuantumCircuit(1) qc.ry(3 * math.pi/4, 0) A. 0.8536 B. 0.5 C. 0.1464 D. 1.0 And the answer is C. But I ...
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2 votes
1 answer
94 views

Accuracy of Grover algorithm is 100% for 2 qubit, 94.5% on 3 qubit and 96.2% for 4 qubit on simulator. Why it decreasing and then again increasing?

The accuracy of Grover's algorithm decreases for 3 qubit then increases for 4 qubit and then again increases for 5-qubit on simulator (qasm simulator) with pi/4(sqrt N) iterations. What is the reason ...
2 votes
0 answers
96 views

How to formulate QUBO as summation quadratic and linear parts of K-graph coloring problem?

While trying to understand the graph coloring problem with VQE using the QUBO Formulation mentioned section "5.2 Graph Coloring". Mentioned article prepared the QUBO directly in to matrix ...
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1 vote
0 answers
27 views

Getting different sets of plots for the teleportation algorithm in Composer and Lab

I tried recreating the quantum teleportation circuit (in the Qiskit Foundation Youtube Playlist) both in Lab and Composer and getting different plots for each. Here is circuit and histogram from ...
3 votes
2 answers
360 views

'Internal error. Error code 9999' when running job on IBMQ

I'm trying to run a series of circuits in a job and I keep getting this error message which I haven't been able to find the meaning of anywhere in qiskit's documentation, online, etc. The job appears ...
2 votes
1 answer
197 views

Bell state measurement IBM circuit composer

This is my first post in this forum so it is likely that I'll make some rookie mistakes here. In the simple Bell state circuit in IBM circuit composer we measure the first qubit and for this seed we ...
5 votes
2 answers
575 views

Can I initialize only one qubit in a 4-qubit circuit?

I wonder if there's a way we can initialize the quantum state only for part of the qubits in a quantum circuit. Say if I have a quantum circuit defined as ...
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1 vote
1 answer
60 views

queueinfo() module in Qiskit

I want to know how to use queueinfo() module in IBM Qiskit. When I type job.QueueInfo(), it says "QueueInfo" is not defined. How to import it? I'm trying to use queueinfo() to know the time ...
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5 votes
1 answer
75 views

Is it possible to set quantum volume in IBM Quantum simulator?

A quantum volume serves as a metric of a quantum processor quality. So far, IBM Quantum provides processors with quantum volume up to 128. Freely accessbile processors have QV up to 32. A user using ...
1 vote
0 answers
30 views

Accessing more than 5-qubit IBM Quantum Computer [duplicate]

I'm doing a university project related to Physics using IBM Qiskit. I want to know how to get access to Quantum Computers with more than 5-qubits (preferably more than 10 qubits)? My account ...
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3 votes
1 answer
122 views

How can I add readout error in constructing a quantum noise model?

I'm trying to construct a quantum noise model with readout error only: qiskit.providers.aer.noise.NoiseModel.add_readout_error. However, when I try to specify the ...
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7 votes
1 answer
194 views

$T_2>2T_1$ qubits on the ibm_washington quantum processor

I have been checking out the parameters of the new ibm_washington processor and I have the following doubt about the calibration data provided by them. Checking out the relaxation and dephasing times ...
1 vote
1 answer
172 views

Tweak the parameter `p` of QAOA in qiskit

I am solving a QUBO using QAOA. It works flawlessly with default parameters for smaller instances of the problem, but my RAM is saturated when I try to solve a problem of size 15. I suspect this can ...
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1 vote
1 answer
73 views

Simulating readout errors on aer simulator

I'm trying to simulate quantum experiments using a customized noise model. Here's my code: ...
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2 votes
1 answer
450 views

What happened to the processor IBMQ_16_melbourne?

I'm a beginner, but in some books and references i use they talk about an ibm processor called IBMQ_16_melbourne, what happened to it? Can it get back up and running? Are there any other free ...
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0 votes
2 answers
241 views

How to multiply two vectors (kets) in qiskit?

Hi does anyone know how i could write a program to get the product of something like |1>|0>|0>?
4 votes
2 answers
141 views

Why aren’t repetition codes used to encode qubits in superposition states?

I just finished reading the section of the qiskit textbook on quantum error correction using repetition codes(https://qiskit.org/textbook/ch-quantum-hardware/error-correction-repetition-code.html) and ...
0 votes
1 answer
178 views

Hadamard cascade

Anyone of you can explain (with mathematical steps) me this circuit: I do not understand why the first qubit phase (as show on IBM composer) is influenced by the second. More precisely: In circuit ...
4 votes
2 answers
175 views

Enable qiskit editor in composer

For educational purposes I would like to make some circuits in the nice IBM quantum experience circuit composer GUI. The only problem is that the set of gates I can use here is quite limited (I would ...
2 votes
0 answers
86 views

Eigenvalues and energy levels of 1D Heisenberg model using real Quantum Computers?

The 1D Quantum Heisenberg model is $$H_\textrm{Heisenberg} = -~J \sum_{\langle i\ j\rangle} \hat{S}_{i} \cdot \hat{S}_{j}$$ where each spin is an operator. For simple cases, for example, a system with ...
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1 vote
1 answer
149 views

How to select the statevetor of a qubit in a multiqubit circuit in qiskit?

I need to use and plot the state of the first qubit in my multiqubit circuit, but the issue is that I need to use post selection - I want only the results of which the other qubits in the circuit are ...
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1 vote
0 answers
97 views

How can I get the results from simulating noise models?

I'm trying to run some simulations of my quantum circuits using qasm simulator. I first tried to import the noise data from a quantum device and then use that information on qasm. Here's part of my ...
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1 vote
0 answers
61 views

Solving Particle in Box problem using Qiskit

I am new to quantum computing, I would like to ask how can I solve simple particle in box problem using qiskit which allows to compute the bound states in finite quantum well. Finite quantum well
6 votes
1 answer
353 views

How can I run a VQE on one of IBMQ's Quantum Computers

I have implemented a VQE based on Qiskit's VQE function and want to run that on an actual quantum computer. My understanding was, that an IBMQ backend can be passed into the function as a Quantum ...
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1 vote
2 answers
80 views

Are we using the real-time error information in simulating noise on qasm?

I'm trying to run some quantum circuits on qasm simulator using the noise information from IBM Q quantum device: ...
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5 votes
1 answer
118 views

Where does the "correction" in quantum error correction occur, specifically when using repetition codes?

I'm reading the part of the qiskit textbook that deals with this (https://qiskit.org/textbook/ch-quantum-hardware/error-correction-repetition-code.html) and so far it seems as though they're just ...
1 vote
2 answers
127 views

How to apply gates based on a random decision on the IBM quantum computer?

I want to run a circuit on an IBM quantum computer, and this circuit involves gates that are either applied or not based on a (classical) random decision. As a minimal example, imagine a circuit with ...
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6 votes
1 answer
76 views

Do individual qubits on IBM quantum processors share the same control unit?

I want to investigate the maximum possible parallelism of quantum operations on a specific IBM device (such as the latest heavy-hex architecture), which requires a basic knowledge of their control ...
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2 votes
1 answer
203 views

Is there a faster way to do real-time error mitigation in qiskit?

I'm working on the readout error mitigation on a set of results obtained from different quantum circuits. The method I want to apply is to generate the confusion matrix for each quantum circuit (as ...
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1 vote
1 answer
44 views

Can I use `job_manager` to get memories for 3 parts of the experiment?

Here's part of the code I'm working on: ...
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2 votes
1 answer
735 views

What is difference between qasm_simulator and ibmq_qasm_simulator?

There are many ways how to simulate a quantum circuit on IBM Q. However, in partiuclar I am interested in a difference between qasm_simulator and ...
2 votes
1 answer
106 views

Quantum state inconsistency between book and IBM quantum composer

$ \newcommand{\ket}[1]{|#1\rangle} \newcommand{\tens}[1]{% \mathbin{\mathop{\otimes}\limits_{#1}} }$I'm trying to self-learn quantum information basics by reading Dancing with Qubits by Robert Sutor....
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3 votes
3 answers
516 views

Are these two circuits equivalent in performing controlled time-evolution?

I want to perform the controlled time-evolution of some 2 or 3-qubit Hamiltonian. Say we have this example: $$ H= Z_0\otimes Z_1 + Z_1\otimes Z_2 $$ The circuit performing the time-evolution ...
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0 votes
1 answer
86 views

How to execute a qiskit circuit from strangeworks hub? [closed]

I would like to execute a circuit in the strangeworks hub on IBM's "ibm_nairobi" system. Could someone just please send me a general layout of execute and provide a command for stangeworks ...
4 votes
3 answers
1k views

Saving statevector on more than one location in a quantum circuit in Qiskit

So, I'm fairly new to Qiskit, and I've been playing around and following the tutorials from the Qiskit textbook. However, there is one thing I fail to understand/implement: for a quantum circuit with ...
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2 votes
0 answers
187 views

How can I add custom pulse gate to the Qiskit circuit?

I tried to make my pulse and get the pulse into the circuit. But it seems not working properly. The code and the result are below. Just change the 'x' to the 'h' (hadamard) with the same piecewise ...
4 votes
1 answer
221 views

HHL - the result is correct for one matrix but wrong for another one

I tried to run HHL algorithm in new version of Qiskit (0.29). Firstly I tried to solve a diagonal system 4x4 with matrix [[1,0,0,0],[0,2,0,0],[0,0,3,0],[0,0,0,4]] ...
4 votes
2 answers
779 views

Cannot get a provider from IBMQ

My code is: from qiskit import IBMQ IBMQ.load_account() provider = IBMQ.get_provider('ibm-q') qcomp = provider.get_backend('ibmq_16_melbourne') but ...
3 votes
1 answer
519 views

Simulating OpenQASM 2.0 in Qiskit?

I'm just getting started with OpenQASM, but I'm feeling a bit confused. Is there a way to run the .qasm file I've written in Qiskit (i.e. in Python), or is OpenQasm ...
6 votes
1 answer
386 views

What is the basic hardware gate library in the IBM & google?

I need to know what is the basic hardware gate library in hardware IBM and Google? I mean, which one of the gates can be implemented directly in the hardware. I would be very grateful if everyone ...
1 vote
1 answer
79 views

Can I extract information from a single shot efficiently?

I'm running a quantum simulation and want to obtain some information from a single shot of an experiment. Here's part of the code I'm working on: ...
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2 votes
2 answers
274 views

IBM Quantum: Are ibmq_5_yorktown and ibmqx2 different devices?

When I run provider.backends(), ibmqx2 is listed as an available backend, but is not listed on the IBMQ systems page. This file ...
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