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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IBM Quantum Lab - Server unavailable or unreachable. Would you like to restart?

In the following circuit, I want to perform tomography on the qubits 0,1,2,3 after qubits 4,5,6,7,8,9 are measured. I run the circuit using with measurement gates on qubits 4,5,6,7,8,9 with the ...
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How to deterministically add two integers on a quantum computer

I am new to the Quantum Computer world. I understand the basics of Quantum mechanics and I have watched a few lectures on Quantum computers, Quantum gates and played a bit on IBM QC. As far as I ...
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which device had the best Average coherence time?

These are the IBM backend overview, do: Avg.T1/T2: here stand for the Average decoherence time or coherence time?
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How can I know the number of qubits used in a job in qiskit?

How can I know the number of qubits used in a job in qiskit? I can always do something like ...
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Hadamard on first qubit for two qubit state doesn't output what it should on Qiskit

I'm using python qiskit==0.36.2. The following code: ...
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2 votes
1 answer
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How can I write if conditions on quantum registers using qiskit

There is a quantum register measured to state $\left|00\right> $ How can i write a code to check weather the first qubit in measured state is 1 or zero and if 1 do some operations or if 0 do other ...
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Qiskit QRAM encoding classical data into quantum state

I'm having trouble to encode classical data into quantum state in Qiskit IBM Quantum Lab. Let me explain the problem clearly: For university purpose I have to encode two 4-dimensional vectors with ...
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2 votes
2 answers
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QV circuits fail to execute in real devices

I tried to change a little the code here for running the quantum volume circuits in real devices. My code is ...
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Error with optimizer in torch-train program

I would like to train hybrid QNN models with the torch-train program of IBMQ but I have the following error: Object of type Adam is not JSON serializable. What optimizer can we use with "torch-...
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Can someone explain to me what is T gate and tdg like im five?

I'm newbie to quantum computing, i read about these two gates on IBM quantum computing docs, but I can't seem to understand what is t-gate and tdg or t-dagger, can someone give me a simple explanation ...
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3 votes
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How to estimate Qiskit circuit runtime before sending to run on IBM real quantum device?

Qiskit, I tried to estimate circuit runtime using gate_length from Backend.properties() but its accuracy is very low (real system is 3.5 seconds, estimation is 0.00002 seconds). So, are there other ...
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2 votes
1 answer
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Performance metrics in QSVM

I have implemented QSVM on breast cancer dataset using link: "https://qiskit.org/documentation/stable/0.24/tutorials/machine_learning/01_qsvm_classification.html" but unable to compute other ...
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Converting data into a SHA256 hash using Qiskit quantum computer

I was wondering how can we convert data into a hash using Qiskit quantum computer? e.g, this code below will generate a SHA256 hash based on random data. ...
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Is there a way to connect a IBM quantum lab code to an Unreal Engine project?

I would like to know whether someone tried this before, I'm interested in be able to connect this tools. I know that Unreal Engine has a plugin to program with python, that all I know. I'll really ...
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What is $j$ in the state $|\psi\rangle=\sqrt{(1-p)}|0\rangle + e^{j\phi}\sqrt{p}|1\rangle$?

What is the j in the single qubit state equation in the Quantum Phase section? https://quantum-computing.ibm.com/composer/docs/iqx/guide/introducing-qubit-phase it's not defined in the page itself (...
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2 votes
2 answers
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Can I Convert a Qubit in complex form to polar form?

Let's say I have a qubit $$\left| \psi \right> = (\alpha_1 + i\alpha_2 ) \left|0\right> + (\beta_1 + i\beta_2 )\left|1\right>$$ Can I able convert this to polar form $$|\psi \rangle = \cos\...
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4 answers
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How are IBM's 127 qubits more potent than the 5760 qubits D-Wave - Advantage_system6.1?

Hi I'm a newbie in quantum computing recently I had a look at the AWS braket and I've seen they had a machine called D-Wave - Advantage_system6.1 that has 5760 qubits but when I googled the highest ...
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1 answer
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Iterative quantum phase estimation - real device

I'm trying to implement the iterative quantum phase estimation on a real (IBM) quantum computer. I'm using the code below. When I run this code on a simulator the results are the expected ones, but ...
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3 votes
2 answers
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Understanding the output of a Deutsch-Jozsa circuit

I'm looking at the Deustch-Jozsa algorithm. While reading this Qiskit tutorial. I didn't understand what the presented result in plot mean. That is, why the output 1111 means a balanced function? What ...
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Qiskit library.gaussian() does not accept parametric expression

I'm trying to build a gaussian pulse in qiskit where I keep the amplitude as a parameter but for the followig code ...
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1 answer
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Generating a random 32-byte hex integer using Qiskit

Hello I posted here yesterday about generating random 16 digits using Qiskit, and a gentle guy helped me but how about a string? How can I generate random 256 bit key in hex format in a superposition ...
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1 vote
2 answers
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How do I use the quantum searching algorithm to loop search through a datafile in qiskit?

I have a localhost index.html has a table contains names and address and balances etc... also there is a search bar on the home page to go through the pages, the interesting thing is, there is loooot ...
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2 votes
1 answer
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Question about mock backends!

I recently learned about the mock backends or the fake backends provided by Qiskit and I was wondering, do they behave the same way IBMQ systems backends like (ibmq_brooklyn)? also, can I depend on ...
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2 votes
1 answer
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How does a quantum computer find the correct password faster than classical computers using brute-force?

I didn't get this part right! For example, we have an online box with a 16-digit password, and we don't know what the password is! How can a quantum computer find the correct password faster than ...
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2 votes
2 answers
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IBM Quantum Experiment CNOT

I have a beginner question regarding CNOT-Gates on IBM Quantum. Assuming the following simple circuit: ...
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How to run Quantum Instance into ibmq_qasm_simulator

I have tried to run Shor's algorithm using IBM high performance simulator. I am currently using QuantumInstance to factorize a number. The code is provided below: <...
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ValueError: setting an array element with a sequence for qiskit

I am trying to implement Quantum Kernel Ridge Regression (replacing the classical kernel with quantum kernel) in qiskit. The shape of my input x is (7165 x 529) and due to reshaping errors, I added an ...
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1 answer
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Circuit Construction using IBM Quantum Composer

I am trying to create the following circuit in IBM Quantum Composer but I cannot add the last H gate correctly. It falls in the wrong place. Why?
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Design Digital logic circuit in IBM quantum lab

This is my first question here. I've started doing research in quantum computing. In Digital Logic circuits, there are many circuits (like parity generator, checker, demux etc.) that can be ...
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How can I use an if function on the IBMQ experience

I have seen elsewhere on here that the quantum simulators allow boolean functions (I'm using the if function) but the actual quantum computer doesn't currently support if functions; is there a ...
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-1 votes
1 answer
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Quantum ripple-carry adder construction

I am attempting to build a 2-bit ripple-carry adder, using IBM Quantum Experience composer, but I'm confused on how to construct the carry transpose that is shown at the bottom?
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What is the relation between the database made up of N elements and the index made up of a string length n in the query model?

I am working on a circuit model that contains a blackbox (query) and do not understand the relationship between what is in the black box and the way we get out the value of the element we index. The ...
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1 vote
1 answer
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How to access a qiskit runtime job and query time_taken?

I am trying to execute qiskit runtime jobs on simulators and real machines and I would like to extract information about the time taken to execute each runtime job. Since using python ...
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Decompose native gates using Qiskit framework [closed]

I've read the papers about quantum hardware. These papers [1] [2] mention that native gates of IBM quantum computer are $R_x(\pi/2), R_z(\lambda)\space and \space CR \space (Cross Resonance)$ My ...
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1 vote
1 answer
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Is pennylane free?

I was going through the basics of pennylane. I am able to understand that it is used for quantum neural networks. I am not sure whether it is using paid cloud computer or simulator of xandu or ibmq? ...
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2 votes
1 answer
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Qubit State (theta,phi) Dependence on the Readout Error

Do the readout errors on the publicly available IBM quantum computers have any dependency on the state being measured? That is, if we are measuring a qubit in the state $\cos({\theta/2}) |0> + e^{i\...
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2 votes
1 answer
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Why does application of Hadamard gate on $|0\rangle$ inverts the state on bloch sphere?

I am trying to understand what is the affect of Hadamard gate on qubit. So far, I understand that applying $H$ gate on qubit, puts the qubit into superposition state where the probability of the qubit ...
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3 votes
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Quantum Machine Learning Masters thesis topics [closed]

I'm a prefinal year Physics Masters student looking to pursue my thesis in the domain of Quantum computing, particularly in the areas of Quantum Simulation or Quantum Machine Learning (theory/...
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2 votes
1 answer
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Duration of single qubit gate in IBM

how can we calculate the duration of single qubit gate using Qiskit in IBM? In other words if I have to insert a delay in the place of the single qubit gate, how would I know how much delay in ...
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What's the difference between depth and num_tensor_factor in qiskit

Now I'm studying about the quantum circuit in qiskit developed by IBM. The quantum circuit have a several method in itself like depth() and num_tensor_factor(). I don't know what is different between ...
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Unable to interpret output by qiskit

I have built a simple 2 qubit entanglement circuit and wanted to measure using a real quantum device. I ran the below command an dthe have an output that is not what I was expecting. qiskit.providers....
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Maximum depth of a circuit in IBM

Given Quantum Volume and number of qubits of a IBMQ device, what is the formula to calculate the maximum depth of the circuit that gives high fidelity? For example: Let us consider ...
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4 votes
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Quantum State Tomography Implementation in IBMQ

I am working to understand quantum state tomography, specifically using the algorithm presented in PRL 108, 070502. This paper is referenced in IBMQ implementations of QST, both in old deprecated ...
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1 vote
1 answer
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Results are missing for Qiskit runtime program 'sample-expval'

I have ran some circuits using the code for sample-expval, found in the qiskit docs While the jobs finished (they appear in my IBM account), when I retrieve some ...
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2 votes
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Calculating the Inner Product using Quantum Phase Estimation

I'm following the method laid out in https://arxiv.org/abs/2011.03429 (Page 23 Equations 13-23) to calculate the inner product of two amplitude embedded vectors using Quantum Phase Estimation. I'm ...
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1 vote
1 answer
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How can I get IBM's API token?

I need an API token to use IBM's real hardware(greater than 5 qubits) in Qiskit, where can I find the price?
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Sequential Circuits in IBMQ and Qiskit and generating a clock pulse

I am trying to implement the Peres Gate with Feedback from Feynmann Gate feeding back into the third input to Peres Gate. This sequence needs to be repeated. There is also a clock pulse that needs to ...
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What is the number of qubits available on the IBM Quantum Composer per year since it's launch?

I'm not able to even find the information on how many qubits are currently available. Also, I'm not sure what ibmqx2, ibmqx4, etc. means and how they changed through the years.
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4 votes
1 answer
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How can I run Qiskit runtime program with Python package with C++ dependencies?

Recently I was testing Python package on IBM Quantum Lab with Qiskit runtime programs. This package contain C++ and Eigen (C++ lib) dependencies. I don't have root permission so I cannot install it. ...
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Implementing Quantum Walks at IBM

a question about quantum walks, would this circuit be correct to start a quantum walk in a hypercube? I saw something about increment and decrement, but I didn't quite understand how they would work ...
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