Questions tagged [ibm]

For questions about IBM's quantum computing processors and devices. For their cloud-computing service use the [ibm-q-experience] tag instead.

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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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2 votes
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Why is there a frequency difference when performing ramsey experiment with setting neighbor qubits to different state?

For transmon qubits, there is an always-on zz interaction between coupled qubits, thus introducing static zz crosstalk. The figures are from this paper. I know zz crosstalk can change the frequency of ...
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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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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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What use cases are there for 127 qubit QPUs?

IBM have recently announced their 127 qubit Eagle processor. Other approaches, such as Rydberg arrays, have now 256 qubits, as for example in QuEra's QPU QPU. While these are without a doubt ...
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Is the error rate of IBMQ devices full-scale (% FS) or on percentage of reading (% RD)?

The error rates that I found on the calibration files are given in percentage, but I couldn't find whether it is calculated on full-scale (% FS) or on percentage of reading (% RD). If I do $20000$ ...
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Can we find which qubits are multiplexed for readout in IBMQ systems?

This question has a couple of parts: Do all IBM systems (except IBM Armonk) utilize frequency division multiplexing for qubit readout? If yes, is there a way of finding which qubits constitute a ...
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Can the ancilla for Qiskit's mcx with mode="recursion" be dirty?

I think their implementation is close to the one from here which does use a dirty ancilla, but I just want to make sure
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Qiskit- Building an oracle to test on Qiskit's Grover

I want to build an oracle with multiple state solutions. For example: For n=4 qubits, I want the state solutions to be 1111, 1101, 1110 and 1100. So, as you can see, in all solutions, there are two ...
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Strange behaviour of IdentityGate IGate in IBM Q Composer

Can anyone explain the strange impact of the IGate in the enclosed quantum teleportation setup in view of the computational basis states? Any help is welcome!
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3 votes
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Difference between Aer.get_backend('aer_simulator') and AerSimulator()

In Qiskit, there are several ways to choose simulator: one is from qiskit import Aer backend = Aer.get_backend('aer_simulator') result = backend.run(circ).result() ...
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How much information is stored in entangled states (IBM report Quantum Decade)?

In its report Quantum Decade, IBM claims that we need 512 classical bits to represent two-qubits entangled state (see graphic on pg. 2 in the report). This seems a little bit odd to me. Lets have a ...
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2 votes
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Why can two target superconducting processors with the same layout get different transpilation results?

I compile and run the same small Grover circuit for 6 different processors. ibmq_santago, manila and bogota all have a linear layout, while quito, belem and lima have qubits arranged in a T-shape. I ...
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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 represent the inefficient measurement in terms of IBM circuit?

Given $P^{0}=|0\rangle \langle 0|$ and $P^{1}=|1\rangle \langle 1|$, how can one represent the measurement $(1-a) \textbf{I}/2 + a P^{k}$ $(k=0,1)$, on a state, in terms of an IBM circuit?
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Why probabilites are not 50-50 in this simple circuit?

I am "brand new" to IBM quantum computing. Just created an account and tried my first circuit with a Hadamard applied to $|0 \rangle$ which should lead to $(|0\rangle + | 1 \rangle)/\sqrt{2}$...
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What are the runtimes of the different modes of qiskit's mcx?

Qiskit's mcx has four different modes: 'noancilla': Requires 0 ancilla qubits. 'recursion': Requires 1 ancilla qubit if more than 4 controls are used, otherwise 0. 'v-chain': Requires 2 less ancillas ...
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Good resources for seeing qubit control pulse shapes (Transmon qubits)

I'm looking for resources which can show the pulse shapes for various single-qubit and two-qubit gates. More specifically, is there any resource which can show me calibrated pulse shapes so that I can ...
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4 votes
2 answers
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When will Qiskit Runtime be available to all users?

IBM's Qiskit Runtime was recently made available to a select group of users. Have they announced when it will be available to all users or when they might open it back up to a second round of new ...
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1 answer
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Qiskit - lesson 3 - with Abe

Coding for Qiskit I watched this video: https://www.youtube.com/watch?v=RrUTwq5jKM4 Using Mac OS Big Sur Using Jupyter 2.0.8 Using Python 3.8 The below code did not work and therefore installed ...
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How do I send a quantum circuit to IBM for execution?

I have, let's say, the following quantum circuit: The QASM code of this quantum scheme has the following form: ...
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2 votes
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IBM Quantum API for Java Developers

As far as I know, IBM Quantum provides two types of APIs: one for Qiskit, and the other for third-party uses (API for developers). In this question, there are several arguments about using the API for ...
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1 answer
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CNOT error rate of 1 in IBM backends

I have noticed that some CNOT gates (for instance, between qubits 1 and 2 in ibmq_casablanca) display an error rate of 1 while typical error rates are of course ...
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1 vote
1 answer
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IBM quantum computer giving the wrong result?

This is the first time I am using the IBM quantum computer. I tried to run a circuit (see below the first picture) but the results I got don't match the theoretical results shown (see below the second ...
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2 votes
2 answers
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Who is responsible for implementing quantum error correction?

There are various options for error correction. For example, the Shore code or a whole class of surface codes. But I don't really understand at what level they should be implemented. For example, I ...
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Does a quantum computer exist today? [closed]

I agree that this may not be an easy question to answer. But lately, I increasingly come across the fact that many news materials and research papers in the field of quantum technologies say that at ...
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3 votes
1 answer
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Is there any way to obtain the number of qubits of a given backend in Qiskit?

I'm testing out a program in different IBMQ mock backends, and I want the program to use the maximum number of qubits in each case. Is there any function/method to extract the number of qubits of a ...
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1 vote
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Can I use Quantum lab during IBM Quantum certification exam? [closed]

Hello I am about to take the IBM Quantum Qiskit dev exam. I don't know if I can use the quantum lab (Qiskit) during the exam. Does anyone know?
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6 votes
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Optical quantum computers VS Superconducting quantum computers VS Electron-spin quantum computers

One of the main problems of superconducting quantum computers is that it is necessary to maintain a very low temperature (near absolute zero). Such cooling is very expensive and complex. Why, then, ...
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1 vote
1 answer
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Why is a 15-qubit IBM quantum computer not working correctly?

I just wanted to implement an algorithm for adding two 2-bit binary numbers. And it works, but only on an IBM 32-qubit simulator. And on a real 15-qubit computer, ibmq_16_melbourne, it produces very ...
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9 votes
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Characteristics of the IBM quantum computer

On the IBM Quantum Composer website, there are characteristics of qubit computers. For example, ibmq_16_melbourne. But there is no description anywhere of what: ...
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1 answer
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Error 400 on submission request on job that ran before

since today in the morning I am always getting the following error while running a job on IBM Sydney "'Error submitting job: '400 Client Error: Bad Request for url: https://api-qcon.quantum-...
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2 votes
1 answer
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Qiskit: 3 applications of identity with arbitrary SU(2) is universal?

We know that the CNOT gate together with arbitrary SU(2) gates can be used to perfectly implement arbitrary SU(4) gates with 3 applications of the CNOT. I am using the Qiskit library and testing how ...
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1 answer
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Error while running Qiskit code on real quantum computer

I was trying to run this code on a quantum computer but I was getting an error can anyone suggest how to resolve this error? ...
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1 vote
2 answers
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Multiple Providers on IBMQ

I am attempting to run parallel computations on two different backends from within the same Jupyter notebook, though it appears these two jobs are running sequentially. I understand the jobs will be ...
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1 vote
1 answer
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processing between sequential executions

Regarding real quantum computers of IBM, can one execute a circuit that contains measurements and afterwards get counts and then, based on the results of measurements (from counts), decide if to build ...
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2 votes
1 answer
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Is it possible to modify pulse schedules in QASM?

Is it possible to modify a pulse schedule of a circuit compiled using QASM? I know this is possible using OpenPulse, but it seems none of the IBM backends support OpenPulse. So is it possible to do ...
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6 votes
3 answers
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How to create the state $\vert 0 \rangle+i \vert 1 \rangle$ using elementary gates?

I am trying to write $|0\rangle+i|1\rangle$ in terms of elementary gates like H, CNOT, Pauli Y, using the IBM QE circuit composer. I was thinking some kind of combination of H and Y since $Y|0\rangle=...
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3 votes
1 answer
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Can I access device specifications of IBMQ paying devices?

I need to perform some tests for my thesis in real quantum computers, however, I only have access to IBM's free quantum devices (the maximum number of qubits I can use is 15, in ...
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-2 votes
1 answer
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How to deal with job submission error in IBM? [closed]

I keep on getting this error no matter how many circuits I run in the backend 'ibmq_athens'. It says 'Max retries exceeded with URL'. Can someone explain why I am getting this error message. The main ...
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3 votes
1 answer
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Qiskit's c_if and conditioned operations on a real quantum computer

Can Qiskit's c_if be used on a real quantum computer of IBM? And if it can, can it put a condition only on Qiskit gates like X, H, U1, U2, etc, or is there some way ...
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5 votes
2 answers
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Topology graphs of IBM's quantum computers

What is the meaning of the topology graphs of IBM's quantum computers? How should it be interpreted? For example, how should I understand the following graph?
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3 votes
1 answer
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Kernel stopping when solving water molecule ground state

I'm new to QISKIT Aqua and I'm trying to follow the Ground State tutorial to solve the Water molecule ground state, but when I execute the calculations the kernel stops. I'm using IBM Q Experience ...
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3 votes
1 answer
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Is every computer in IBM's fleet based on superconductivity?

I'm currently writing my thesis and I'd like to know which computer is based on a superconductive architecture to run some simulations. Thanks for help in advance.
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2 votes
1 answer
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Is Noise model for quantum prototypes accurate in Qiskit

We know that in Qiskit noise models modeling specific quantum machine prototypes exist and can be inserted into the code. However, are these models fixed in nature or they continuously improve ...
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2 votes
1 answer
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Connectivity in Grover's algorithm on real quantum computers

Everytime I execute Grover's search algorithm on IBM real quantum computers I get a wrong answer (it doesn't find the correct winner state) unless I use only 2 qubits. For any higher number of qubits ...
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1 vote
1 answer
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Mechanism of measurement in IBM quantum devices

I am trying to find out about the mechanism of measurement in IBM Q devices. To be specific, if I apply two Hadamard gates on the first qubit and identity on the second then is it possible to ...
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1 vote
1 answer
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How to measure a quantum circuit's execution time on a real IBM device?

I am executing a quantum circuit on an IBM quantum device and I need to start a timer as soon as the job in the queue starts running. I have already used: ...
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4 votes
1 answer
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IBMQ backends: How can I know the repetition rate and depth limits of real devices?

When trying to execute complex quantum circuits on IBMQ real devices, one can encounter a typical error (ERROR_RUNNING_JOB) with the message ...
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2 votes
2 answers
127 views

Is there a quantum processor with physically implemented Toffoli gate?

Recently, I came across the article Realization of efficient quantum gates with a superconducting qubit-qutrit circuit where its authors proposed a physical implementation of three qubits quantum ...
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