All Questions
Tagged with ibm-q-experience ibm-q-experience or
675 questions
23
votes
2
answers
12k
views
What is a "barrier" in Qiskit circuits?
I just started studying IBM Qiskit, and cannot find details about the barrier method on the QuantumCircuit class. It is shown in the circuit drawing, but I never heard about it after reading quantum ...
- 909
20
votes
3
answers
2k
views
What would a very simple quantum program look like?
After reading the "first programmable quantum photonic chip". I was wondering just what software for a computer that uses quantum entanglement would be like.
Is there any example of code for specific ...
- 795
19
votes
1
answer
10k
views
What's meant by the depth of a quantum circuit?
I'm using Qiskit to create quantum circuits wherein I've this attribute called depth. The documentation states it is the length of the critical path here. What does ...
- 577
18
votes
1
answer
4k
views
Which subatomic particle does each company use in quantum computing?
Probably each company (Google, Amazon, Intel, IBM, Microsoft, D-Wave and so on) uses a mix of subatomic particles and technologies. I would like to know which particles/technologies are used by each ...
18
votes
2
answers
10k
views
How to implement the 4 Bell states on the IBM Q (composer)?
I would like to simulate the 4 "Bell States" on the IBM composer?
How can I best implement those 4 Bell states using the existing set of gates ?
Here below you see the definition of the 4 Bell ...
- 1,158
13
votes
2
answers
5k
views
How can a controlled-Ry be made from CNOTs and rotations?
I want to be able to applied controlled versions of the $R_y$ gate (rotation around the Y axis) for real devices on the IBM Q Experience. Can this be done? If so, how?
- 11.5k
12
votes
2
answers
3k
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:
...
- 481
12
votes
4
answers
5k
views
How to quickly calculate the custom U3 gate parameters $\theta, \phi$ and $\lambda$ for any unitary?
In IBM Qiskit and Quantum Experience, the custom U3 gate is defined as
$$
U(\theta, \phi, \lambda) =
\begin{pmatrix}
\cos\left(\frac{\theta}{2}\right) & -e^{...
- 17.8k
11
votes
1
answer
581
views
Submitting jobs to IBMQ backend via HTTP API Requests
Qiskit can be used to submit jobs to IBM devices using Python (or Swift and JavaScript). But what if I want to use a different language?
For example, suppose I have a specific circuit I want to run. ...
- 11.5k
11
votes
3
answers
2k
views
Implementation of the oracle of Grover's algorithm on IBM Q using three qubits
I am trying to get used to IBM Q by implementing three qubits Grover's algorithm but having difficulty to implement the oracle.
Could you show how to do that or suggest some good resources to get ...
- 842
11
votes
1
answer
2k
views
Is it possible to run a general implementation Shor's algorithm on a real IBM quantum computer at least for N = 15?
I need to make a general implementation of Shor's algorithm that factors, at least, N = 15. I have been able to perform an implementation that works in simulators, with ProjectQ, but when running it ...
- 111
10
votes
2
answers
2k
views
Quantum algorithm for linear systems of equations (HHL09): Step 2 - Preparation of the initial states $|\Psi_0\rangle$ and $|b\rangle$
This is a continuation of Quantum algorithm for linear systems of equations (HHL09): Step 2 - What is $|\Psi_0\rangle$?
In the paper: Quantum algorithm for linear systems of equations (Harrow, ...
- 17.8k
9
votes
1
answer
4k
views
Phase-Shift Gate in Qiskit
How to implement the phase shift gate in qiskit or ibmq?
Phase Shift Gate : $$\begin{pmatrix}e^{ia} && 0 \\ 0 && e^{ia}\end{pmatrix} = e^{ia}I$$
- 185
9
votes
3
answers
4k
views
How to implement the "Square root of Swap gate" on the IBM Q (composer)?
I would like to simulate a quantum algorithm where one of the steps is "Square root of Swap gate" between 2 qubits.
How can I implement this step using the IBM composer?
- 1,158
9
votes
2
answers
854
views
Qubits specification on IBMQ devices
As it is shown here, CNOT gates between different qubits have different error rates. I have the following questions:
1) While defining a circuit on QISkit, does ...
- 495
9
votes
3
answers
3k
views
Access results from an experiment without having to run the script again
I have ran an experiment in one of the IBM processors and the work has finished. However, I can not obtain the data as histograms or counts in the qiskit notebook because the experiment was concluded ...
- 123
8
votes
2
answers
1k
views
Changing one qubit causes changes in another independent qubit on ibmqx2 in IBM Q Experience
When I run this program on ibmqx2 (the backend matters) in IBM Q Experience, the results are interesting. Essentially, the program measures the error rate on $|q_0\rangle$ after fiddling with $|q_1\...
- 137
8
votes
3
answers
199
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 ...
- 333
8
votes
2
answers
523
views
Apply readout error mitigation to mid-circuit measurement
I'm trying to construct a quantum circuit with 3 mid-circuit measurements, here's an example:
...
- 2,408
8
votes
1
answer
2k
views
What are the differences between the different transpiler optimization levels in qiskit
I am currently running a simple algorithm using Qiskit and I am running it for various transpiler optimization levels (0-3). I wish to know what exactly occurs differently when for example I run the ...
- 128
8
votes
1
answer
2k
views
Depolarizing channel implementation on IBM Q
Given a single qubit in the computational basis, $|\psi\rangle =\alpha |0\rangle + \beta|1\rangle$, the density matrix is $\rho=|\psi\rangle\langle\psi|=\begin{pmatrix} \alpha^2 & \alpha \beta^*\\
...
- 495
8
votes
1
answer
343
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 ...
8
votes
2
answers
565
views
Practical Implementations of QECCs in IBM Q Experience
I am learning how to program the IBM Q Experience quantum computers in order to learn more about how does it work and in order to perform some experiments in it. By doing so I was wondering what are ...
8
votes
1
answer
1k
views
How to delete pending jobs on IBM Quantum Computer to retrieve units?
I am trying to run some code using qiskit, but I get the error message, that I have run out of necessary Experiment Units. I ...
- 1,049
8
votes
1
answer
2k
views
Physical implementation of gates on IBM Q
There is a lot of quantum gates in IBM Q Composer, however, only few are implemented physically while others can be composed of them.
When one looks at description of a quantum processor in IBM Q ...
- 14.9k
8
votes
1
answer
530
views
How does measurement calibration work?
One of the possible ways to improve the results of an experiment on the IBM machine using the Qiskit language is to use the measurement calibration methods. This is the link to the documentation.
I ...
7
votes
3
answers
3k
views
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 ...
- 193
7
votes
1
answer
2k
views
Why use U2 and U1 gate in IBM quantum computers?
I was wondering why IBM's computer were using U1 and U2 gates as part of there basis gates since as I understood, they are particular cases of the U3 gate. Why not just use U3 gate instead ?
Thanks ...
- 345
7
votes
2
answers
3k
views
How do I get the names of all currently available IBMQ devices?
How do I get the names of all currently available IBMQ devices?
- 161
7
votes
2
answers
2k
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 ...
- 918
7
votes
3
answers
3k
views
How to run a qasm file on IBMQ device?
I can find many qasm examples.
How can I run them on different IBMQ devices?
- 1,423
7
votes
1
answer
1k
views
What is the purpose of the TDG gate in QISKit?
The QISKIT documentation doesn't explain what a TDG gate does and I can't find it anywhere else online.
7
votes
1
answer
339
views
How are Rigetti and IBM QX device parameters related to Kraus operators?
Rigetti reports the following parameters: (https://www.rigetti.com/qpu)
T1, T2* times
1-qubit gate fidelity (F1q)
2-qubit gate fidelity (F2q) and,
read-out fidelity (Fro)
IBM QX reports the ...
- 429
7
votes
2
answers
860
views
How can I get access to IBM Q 20 Tokyo and IBM Q 20 Austin?
How can I get access to IBM Q 20 Tokyo and IBM Q 20 Austin?
In the Q- experience site there is written that the access is for IBM clients only and in the profile there is a "promotional code" that ...
7
votes
1
answer
287
views
Publicly available samples for quantum circuits and/or simulators
With Yosi Rinott and Tomer Shoham we studied various statistical aspects of samples coming from NISQ computers.
My question is about available data consisting of samples from NISQ computers
We would ...
- 201
7
votes
1
answer
670
views
Why is a different convention used for the $Rz$ implementation on IBM Q?
A $z$ rotation gate is defined as
$$
Rz(\theta)=\mathrm{e}^{-i\frac{\theta}{2}Z}=
\begin{pmatrix}
\mathrm{e}^{-i\frac{\theta}{2}} & 0 \\
0 & \mathrm{e}^{i\frac{\theta}{2}}
\end{pmatrix},
$$
...
- 14.9k
7
votes
1
answer
943
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 ...
- 71
6
votes
3
answers
9k
views
How can I obtain transformation matrix of a quantum circuit in the Qiskit?
I need to draw a quantum circuit in Clifford+T library and obtain automatically its transformation matrix. Is there any feature on Qiskit in this case?
- 179
6
votes
1
answer
2k
views
What does the error rate on the IBMQ website mean？
How is the error rate pointed by the arrow defined? How did you get it?
thanks!
- 325
6
votes
2
answers
963
views
What are examples of quantum computing platforms availble for free (other than IBM Q)?
IBM Q is (maybe first) quantum computing platform allowing users to register for free and run algorithm on real quantum processors. There are several processors with usually 5 qubits, however, it is ...
- 14.9k
6
votes
3
answers
120
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=...
- 121
6
votes
2
answers
479
views
How to implement the CCH gate in quantum computers available in clouds?
How to implement CCH gate in quantum computers available in clouds? If there is not any gate directly available for it, what are the possible ways to represent CCH?
- 61
6
votes
2
answers
973
views
Custom gates on IBM Q
I realized that QASM supports custom gates. However, when I tried to create the gate, transpiling error appeared both on simulator and real quantum processor. I suspect that IBM has not implemented ...
- 14.9k
6
votes
3
answers
981
views
Why can I not apply a control gate/function to a gate like T, S, S dagger, ... (using IBM Quantum Experience)? Is there another option?
I am trying to use the circuit composer of the IBM QE. I am doing the inverse QFT on 3 qubits and therefore need a control on T and S dagger gates, but it won't let me.
Does anyone know why or know a ...
- 121
6
votes
1
answer
6k
views
How to make circuit for n-control Z gate( i.e $C^3Z$ )?
I am trying to make circuit for $C^3Z$ gate I have seen a circuit for $C^2Z$ or $CCZ$ gate made by using $CCX$ gate so is there any way to make circuit for $C^3Z$ in this similar manner( i.e by using $...
- 439
6
votes
1
answer
737
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 ...
- 179
6
votes
1
answer
629
views
How to parallelly run a quantum circuit on IBMQ?
I am trying to implement the following circuit
and my code is
The above circuit has size 5 and depth 3. My question is, how can I run the circuit parallelly. I mean, the gate ...
- 325
6
votes
1
answer
951
views
IBM Q devices scheduling of gates with different durations
I was trying to figure out how scheduling works in IBM devices.
The thing that's bugging me is that in the quantum computer implementations I had seen before, the cycle concept is used. Say, for ...
- 149
6
votes
2
answers
651
views
Simple Hadamard Circuit gives incorrect results?
I am running the simplest Hadamard circuit possible - one qubit, initialised to 0, apply H gate, measure in Z basis. When I run the circuit on the simulator I obtain the expected result (50% in 0, 50% ...
- 61
6
votes
1
answer
2k
views
What is the difference between Qiskit execute and the IBMQJobManager?
I was researching how to submit multiple pulse schedules/circuits in the same job and came across 2 methods:
Executing Experiments with qiskit.execute
and ...
- 431