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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13
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3answers
506 views

Why do the IBM and Google processors both have 53 qubits?

As I understand from this IBM post both the IBM and Google teams have independently built 53-qubit processors. What is the significance of the number 53? It is purely coincidental, or is there a ...
9
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1answer
223 views

Current limits on Grover search space

I was wondering why till date Grover search has been implemented only till 3 qubits (corresponding to size of database = 8). Refer this paper The reason why I ask is that we have much larger sized ...
9
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0answers
181 views

Is there a good reason to use T-count minimization for circuits executed on current IBM open quantum systems (real hardware)?

As far as I understood from a series of papers, minimizing the T-count in Clifford+T circuits is essential for fault-tolerant ...
8
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2answers
1k views

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: ...
8
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2answers
746 views

How to explain in layman’s terms the significance of the difference of qubits of the D-Wave and IBM QX?

So, @AndrewO mentioned recently that he has had 'encounters' with people wondering why D-Wave has a lot more qubits than IBM. Of course, this comparison is faulty, since the IBM and D-Wave's machine ...
7
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3answers
120 views

What are the differences between the IBM machines?

I'm quite new to this field, and have started sending jobs to IBM's quantum computers. I have access to around 11 locations. I can see that these have different numbers of qubits within them, and then ...
7
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1answer
1k views

Would IBM's "compiler" turn my identity circuit into nothing?

If I were to create a circuit with the following gate: $$\tag{1}R_\phi = \begin{bmatrix} 1 & 0 \\ 0 & e^{i \phi} \end{bmatrix},$$ with $\phi$ specified to be equal to 0, then the gate that I ...
7
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1answer
349 views

Why does Google's quantum processor outperform IBM's?

I understand that both have 53 qubit devices, yet it is Google that has demonstrated quantum supremacy (although IBM refutes this!). I'm not sure if this is true but it seems like IBM cannot replicate ...
6
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2answers
938 views

What is maximum circuit depth and size IBM Q5 and Q16 could handle?

I'm trying to implement a couple of algorithms on ibmq_16_melbourne, so I need to know if this device is able to handle with depth and size of my current circuit or ...
6
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3answers
106 views

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=...
6
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0answers
50 views

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, ...
5
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2answers
369 views

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?
5
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1answer
927 views

D-Wave systems and IBM Q System One

What is the difference between the D-Wave systems and the newly-born IBM Q System One?
5
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1answer
124 views

Graphing the decoherence of qubits being used to perform an algorithm

How would I be able to graph the decoherence of qubits being used to perform an algorithm? I'm working with the IBMQ Qiskit framework and I'm trying to write a program that allows me to find the ...
5
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1answer
116 views

IBM Q devices' hardware/resource constraints

I tried to look for the resource constraints but so far haven't been able to find them. They are not present in the GitHub repository that usually provides the hardware information for the different ...
4
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1answer
79 views

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 ...
4
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2answers
151 views

Is there a straightforward way to calculate the quantum volume for simple systems?

There are a few people who ask how to calculate IBM's "quantum volume", but it's not clear what the actual mathematical definition of this is. In the answers here, people just point to ...
4
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1answer
101 views

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 ...
4
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0answers
45 views

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 ...
4
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0answers
103 views

Form and effect of the intrinsic Hamiltonian on the IBM machines

I want to understand the form of the intrinsic Hamiltonian of the IBM machines, such as ibmq_16_melbourne, and how this affects the data I get out when waiting ...
3
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2answers
138 views

Why IBM devices have the same number of qubit and the same architecture, but the error rates are different?

Here are two different IBM quantum online devices, Both of them have the 5 qubits and the same architectures. But why do they have different error rate? What's the different between them?
3
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3answers
263 views

How are the IBM's and Google's Hadamard gates fabricated and operated?

There are thousands of articles, books and web sites describing the Hadamard Gate from a theoretical point of view. But I haven't been able to find any photo about any real implementeation of a ...
3
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1answer
404 views

Why qiskit superconducting device native gates different from that of trapped ion device?

For IBMQ device based on superconducting technology, when we transpile the circuit, it is decomposed of U1,U2,U3 and CNOT gates, which are its native gates. However for trapped ion device, its native ...
3
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1answer
167 views

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: ...
3
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1answer
184 views

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 ...
3
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1answer
64 views

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.
3
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1answer
55 views

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 ...
3
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1answer
75 views

IBM Melbourne quantum computer performance and errors

What is the reason for high variation in measurement probability results of a simple 3/4 qubit measurement circuit on IBM Melbourne machine in comparison with the same circuit being run on IBM Vigo/...
3
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1answer
447 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 ...
3
votes
1answer
432 views

How to plot histogram or Bloch sphere for multiple circuits?

I have tried to plot a histogram for the multiple circuits for the code given below. I think I have done it correctly but don't know why it's not working. Please help me out. If possible please solve ...
3
votes
1answer
529 views

IBM's quantum computing capabilities — entangled 18-qubit GHZ states and high coherence times

Here's a blog post that corresponds with what IBM presented at the 2019 March Meeting. In this post, they claim they've measured qubit T1 relaxation times above 500 microseconds, and claim that they'...
3
votes
1answer
86 views

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 ...
3
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1answer
54 views

Graphing T1 using Qiskit

I am trying IBM's code for graphing T1 and I keep getting the following error: ...
3
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0answers
67 views

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 ...
3
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0answers
116 views

Grover's algorithm for 3SAT problem gives erroneous results

I'm writing some code in python with Qiskit that implements Grover's algorithm to solve the 3-SAT problem, but when I run it it doesn't give the correct annswer. I've checked the circuit with the <...
3
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0answers
62 views

Can "experimental data from a quantum computer" be used to test separability probability conjectures?

An article entitled "Experimental data from a quantum computer verifies the generalize Pauli exclusion principle" by Scott E. Smart, David I. Schuster, and David A. Mazziotti has just appeared In the ...
2
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2answers
371 views

Experiment runtime on IBMQ

I have been trying to get the runtime of my experiment on IBM's quantum computer. I am using the classic stuff, i.e ...
2
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1answer
84 views

What extra functionality is available to an IBM Q Network member over a regular IBM Q Experience user

I've been trying to figure out the extra functionality available to IBM Q Network members that are not available to normal ...
2
votes
2answers
58 views

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 ...
2
votes
1answer
99 views

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-...
2
votes
1answer
163 views

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 ...
2
votes
1answer
322 views

IBM Slack links broken

Does anyone know where I can find working Slack invite links to any of IBM's Slack pages? The Slack links on this support page are all broken. Thank you.
2
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1answer
29 views

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 ...
2
votes
1answer
50 views

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 ...
2
votes
1answer
94 views

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 ...
2
votes
2answers
89 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 ...
2
votes
1answer
86 views

Can we simulate quantum many-body systems with IBMQ Experience?

Consider physical systems such as electrons in metals, or Bose-Einstein condensates, or any crystal, which are realised in the real three-dimensional space. If we want to simulate these systems on a ...
2
votes
1answer
52 views

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 $(|0\rangle + | 1 \rangle)/\sqrt{2}$...
2
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1answer
80 views

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 ...
2
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1answer
60 views

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 ...