# 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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### 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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### 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 ...
1 vote
51 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
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### 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 ...
1 vote
140 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 ...
103 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 ...
501 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
54 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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### 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 ...
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1 vote
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### 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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### 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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### $T_2>2T_1$ 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
96 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
43 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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### 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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### 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>?
106 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 ...
163 views

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 ...
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### 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 ...
66 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
69 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
71 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
47 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
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### 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
62 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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### 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
88 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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### 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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### 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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150 views

### Error when running a VQE circuit in IBMQ backends

I want to run a VQE circuit of 4 qubits for a simple Hamiltonian with Qiskit. The circuit run smoothly in simulators. However, when I try to implement it on real IBM' quantum computers it gives me the ...
1 vote
40 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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### 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 ...
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### 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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### 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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63 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 ...
718 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 ...
100 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 ...
167 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]] ...
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495 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 ...
254 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 ...
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### 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
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### 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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### 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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### Do I need to use classical bits in measurement?

I wonder if I have to add classical bits while performing measurement for a single-qubit quantum circuit. The difference to initialize the circuit is ...
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### Measure $\langle \hat{X}\rangle$ and $\langle \hat{Y}\rangle$ from counts

I'm confused about how I can measure $\langle \hat{X}\rangle$ and $\langle \hat{Y}\rangle$ using counts. Here's my code for X: x-basis: ...
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### This is a question about IBM quantum circuit used to generate the quantum cheque state

I'm learning about quantum cheque. And I read "Experimental realization of quantum cheque using a five-qubit quantum computer" which is written by Bikash K. Behera ,Anindita Banerjee and ...
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### How to Implement a noisy identity gate on qiskit?

I can successfully implement the U gate (single qubit) on qiskit, but when I am trying for the identity operation it is not showing any differences with the ideal one .
51 views

### Job ids retrieval from ID. Big set of jobs

I'm in the need of running a lot of jobs in the IBM backends. If one likes to run in parallel two jobs (say, with two different parameters), I have seen in the Jobs ...
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