Questions tagged [simulation]

For questions about simulating either quantum computers or simulating things on quantum computers.

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Simulating Large Quantum Systems with Single T-Gate in Qiskit: Memory Error Beyond Certain Qubit Threshold

I'm currently conducting experiments on unitary t-designs, utilizing random Clifford and T gates within the Qiskit framework. My goal is to simulate quantum circuits that involve the application of a ...
Asim Sharma's user avatar
1 vote
1 answer
68 views

Exponentiating a tensor product of operators acting on disjoint qubit registers

Consider a problem of implementing $\operatorname{e}^{i\bigotimes_j O_j}$, where all the $O_j$ terms act on disjoint sets of qubits. Assume that efficient circuits implementing individual $\...
mavzolej's user avatar
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How do I get the unitary matrix of a circuit?

I'm studying on this textbook but the library has changed meanwhile and running those instructions on my IBM quantum learning notebook will result in errors. What's the current way to draw the unitary ...
Antonio's user avatar
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2 answers
81 views

Using GPUs with Statevector Simulator in Qiskit 1.0

I'm trying to use the AerStatevector method with GPUs. I know that GPUs on my server are correctly configured, and indeed, if I use ...
Roberto Schiattarella's user avatar
5 votes
0 answers
111 views

What is the classical cost of simulating an arbitrary quantum state?

The past couple of years has seen various groups claim quantum advantage/utility only to have their experiments efficiently simulated with classical methods, notably using tensor networks. My question ...
jsbaker's user avatar
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1 answer
101 views

What is the formula for the matrix representation of a general controlled gate?

Suppose I have $n$-qubit circuit. I have a single-qubit gate (e.g. a Pauli gate) at qubit $a$ and it is controlled by the qubit $b$. What is the matrix representation for this controlled gate? The ...
user1747134's user avatar
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1 answer
73 views

How to use qiskit.utils.QuantumInstance API of qiskit?

I am quite struggling with the usage of QuantumInstance API. This API is present in qiskit version 0.32.1 Below is small code: <...
Manu's user avatar
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2 votes
1 answer
42 views

BP + OSD decoder with both loss and Pauli errors

I am trying to implement a bp+osd decoder, using the build-in python package from here: https://github.com/quantumgizmos/bp_osd One of the parameters for the decoder is "channel_probs", ...
David Dentelski's user avatar
3 votes
2 answers
57 views

How to calculate pseudo-threshold of the [[5,1,3]] code analytically to match simulation?

In this answer there is a simple method given to compute the "worst case pseudo-threshold" of the Shor code. I want to apply this to the $[[5,1,3]]$ perfect code. Namely, given a ...
Eric Kubischta's user avatar
1 vote
1 answer
33 views

Microsoft Classic QDK simulator

Is it possible to change the simulator used by the Classic QDK with Python simulation ? It's reported that Classic QDK supports several simulators (sparse, full-state...). Which one is used when ...
Arnaud's user avatar
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1 answer
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What is the best way to parallelise processes across multiple cores when computing logical error rates with Stim and PyMatching?

I am currently trying to compute logical error rates for the surface code using Stim's detector error models and PyMatching for different distances and noise strengths. tl;dr : What is the best ...
Ezequiel Rodriguez Chiacchio's user avatar
3 votes
0 answers
32 views

How to have seperate registers from scrach?

I am very new to quantum computing, so this might be a really simple question. I am coding a quantum computer simulator in python from scrach and I'm not sure how to make registers work. I would just ...
Gytis Vejelis's user avatar
1 vote
1 answer
106 views

Measuring a specific observable using cirq

I am simulating a circuit in cirq, and I need to measure an observable $$A(\theta) = R^\dagger_z(\theta)XR_z(\theta),$$ and I am not quite sure how to do that. My first thought was to apply these ...
Skilopsaros's user avatar
3 votes
1 answer
97 views

Simulate an arbitrary stablizer circuit with only CNOT gates

It is claimed that Informally, this means that any stabilizer circuit can be simulated using CNOT gates alone; the availability of Hadamard and phase gates provides at most a polynomial advantage. ...
user1936752's user avatar
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Capacitance matrix of superconducting qubit

I want to start to do some simulation and design of superconducting qubits. I want to start using qiskit metal, but in order to calculate the capacitance matrix I need to interface it with Ansys. ...
Simona99's user avatar
  • 180
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1 answer
92 views

Run a circuit on "simulator_statevector" of the IBM Quantum Platforms

I would like to obtain the statevector of a QuantumCircuit using the simulator_statevector (and Qiskit) of the IBM Quantum ...
stopper's user avatar
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2 votes
1 answer
71 views

Truncated Qumode States and Support

I am currently running numerical simulations of a single qumode state acted upon by a parameterised unitary. The qumode state is realised as a Fock state with a fixed cutoff dimension $(d)$ and is ...
Song of Physics's user avatar
1 vote
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How to use GPU with qiskit as default and then use parallel GPU setup in distributed computing?

I have a GTX 1600 GPU on my computer and I am confused on how to use cuQuantum, Tensorflow or torch etc to enable GPU for qiskit. Further, one of my friends also have a GPU, we want to use both GPUs ...
Syed Shahmir Kazmi's user avatar
2 votes
1 answer
78 views

Error 'LocalSimulator' with Googlecolab

I have an error when I want to run the 'LocalSimulator'. I am not inside AWS, its mean I runnig from Google Colab. The code is the same on the notebooks from ...
Sandra Rosales's user avatar
0 votes
0 answers
27 views

Tensor network to simulate a specific final entry state

A tensor network can be used to simulate a quantum circuit, especially when we only want the probability of a specific entry (Ex: $|0110\rangle$) but not the full probability of all $2^n$ entries. Can ...
劉承瀚's user avatar
0 votes
0 answers
121 views

Qiskit cant run circuit with reset gate with error

In qiskit if i have a reset gate in a circuit. If i want to add noise to the circuit it wont transpile. For example: ...
Narcano's user avatar
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1 vote
0 answers
25 views

Is it possible to find out the number of timesteps taken by the mesolve/sesolve method in QuTip?

I am simulating a Quantum System in QuTip using qutip.sesolve. As far as I understand it, the solver propagates the state into the future using time steps of ...
Mausklick99's user avatar
3 votes
0 answers
61 views

qiskit QAOA on Aer GPU giving errors

I am trying to run Qiskit QAOA algorithm on using aer simulator and device GPU. But I am not sure how to give this backend in the QAOA algorithm structure. Here is ...
to_batman's user avatar
1 vote
1 answer
69 views

Phase shift on qiskit quantum teleportation simulation

I wonder in Qiskit why the phase shift occurred in my simulation and how I can turn it off. I posted another question regarding the same simulation here, and while I tried to solve this on my own, I ...
quantum_quantum's user avatar
2 votes
0 answers
41 views

Qiskit noisy FakeManila simulator + ZNE

I am trying to run a simple VQE calculation on H2 using FakeManila noise model and ZNE for error mitigation; see code below. The problem is that I can never reach not even close the ground electronic ...
Carlos Murilo Romero Rocha's user avatar
3 votes
1 answer
96 views

Single-shot error correction for the surface code with measurement errors

I am trying to implement a single-shot error correction for the surface code with data + measurement errors (both with prob. p), using the (build-in) BP+OSD decoder. I am mostly following these papers:...
David Dentelski's user avatar
2 votes
0 answers
96 views

Most efficient way to calculate an expectation value of a noisy model in Qiskit

I want to classically simulate quantum circuits with noise. This noise can be a custom one (noise.NoiseModel()) or a fake quantum computer (...
stopper's user avatar
  • 443
0 votes
0 answers
62 views

Is it possible to simulate a quantum algorithm on a classical computer? [duplicate]

I am designing a quantum algorithm that I would like to simulate and test, but I need to be able to simulate it on a classical computer.
Mihir Macwan's user avatar
3 votes
0 answers
37 views

Advantage of quantum computers over classical computers in fully modeling interactions between atoms?

I'm trying to better understand the advantage quantum computers offer in terms of their ability to more accurately model chemical reactions. As a way to come to a deeper understanding, my question is: ...
Poe's user avatar
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1 vote
1 answer
224 views

How does depolarization error accumulate?

Here's my code to define the depolarization error using Qiskit, which included both one and two-qubit errors: ...
IGY's user avatar
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1 vote
0 answers
69 views

Help me to find error in finding Cost Function for SSVQE algorithm [closed]

Q: Build SSVQE's cost function using the following observable: $$O=2II−2XX+3YY−3ZZ\,.$$ This cost function should take in parameters as input. Use the included variational form, with reference states $...
Kishore's user avatar
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1 answer
82 views

Are quantum simulation results more accurate than real IBMQ device results?

Getting two different results from simulation and rel IBMQ device. Which is more accurate?
mr coder's user avatar
5 votes
1 answer
264 views

Qudits in NISQ Devices: Benefits Beyond Dimensional Advantages?

It's clear from foundational research that qudits can provide an enhanced control of the Hilbert space over qubits, and I've encountered references that highlight improved robustness and noise ...
banercat's user avatar
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4 votes
1 answer
355 views

What are the practical applications of quantum computing in engineering by the year 2030?

Are there any engineering problems that quantum computing can solve or simulate, and demonstrate a real advantage over conventional computing by the year 2030? My primary interest is in the business ...
Max's user avatar
  • 85
1 vote
1 answer
65 views

Could a quantum computer simulate any system based on different types of logic? [duplicate]

Quantum computing is based on quantum mechanics (obviously) which has different logical rules than classical/Boolean logic. However, does this mean that a quantum computer could simulate or process ...
vengaq's user avatar
  • 111
3 votes
0 answers
34 views

Compiling pulses with time dependent $\sigma_x$ and $\sigma_y$ control

I have a Hamiltonian of the form: $$ H = c_x(t) \sigma_x + c_y(t) \sigma_y$$ and I want to compile a pulse "P" that has both $\sigma_x$ and $\sigma_y$ control, with different time dependent ...
Annie's user avatar
  • 31
1 vote
1 answer
69 views

Efficiently simulating a BQP circuit and polynomial hierachy collapse

If we were able to simulate a BQP (Bounded-error Quantum Polynomial time) circuit using a classical computer in an efficient manner, does it necessarily mean that the Polynomial Hierarchy (PH) would ...
MonteNero's user avatar
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0 votes
0 answers
32 views

Can I simulate a quantum walk in fourier space?

I would like to simulate a simple quantum walk in Fourier space in Python. I am hoping just to run a 1D quantum walk with a simple Hadamard coin in Fourier space. Is this possible? Do I just need to ...
Saz's user avatar
  • 1
0 votes
1 answer
74 views

Why is Qiskit's QASM simulator giving me incorrect result with VQE?

In the code below, I am using VQE without noise to calculate the minimum expectation value of the two-qubit operator X^X. I get the correct result when I use statevector_simulator but do not get the ...
bisarch's user avatar
  • 189
1 vote
0 answers
36 views

Efficient classical simulation technique to execute this specific quantum circuit

I have a quantum circuit similar to the ones used in VQE methods. One difference is that the angles of the $R_y$ rotations are limited in the range $[0, 0.2]$ (and chosen randomly). In my case, I have ...
stopper's user avatar
  • 443
0 votes
1 answer
81 views

How does the Qiskit AerSimulator performance scale with the circuit depth?

The performance of a full-statevector simulation by the Qiskit AerSimulator scales of course exponentially with the number of qubits, since the dimensionality of the Hilbert space where an $N$-qubits ...
SimoneGasperini's user avatar
1 vote
0 answers
25 views

Can someone explain the behavior called "Aer fast expectation" of Qiskit simulators?

Earlier I asked a question on why statevector_simulator ignores the number of shots when calculating the expectation value of an operator using ...
bisarch's user avatar
  • 189
1 vote
0 answers
53 views

Subespace Search Variational Quantum Eigensolver (SSVQE) with contraints

I am trying to reproduce this paper: https://arxiv.org/pdf/2211.02302.pdf. However, I am having problems in getting the singlet first excited state (S1). The authors in the paper, they use the SSVQE ...
bjail66's user avatar
  • 155
0 votes
0 answers
52 views

Qiskit: Quantum program execution with aer and aer-gpu

I want to run my custom designed encryption algorithm on parallel GPUs and for that reason I am using qiskit-aer-gpu. Currently I am simulating on a single machine. ...
aneela's user avatar
  • 233
1 vote
2 answers
122 views

Can simulations of a quantum algorithm on a classical computer out-perform a classical algorithm?

Has it ever been shown that simulation of a quantum algorithm (e.g., using PyQuil or something?) on a classical computer has out-performed a purely classical algorithm? From what I can tell the ...
IsalanOnkar's user avatar
2 votes
1 answer
83 views

Confusion regarding hardness of BQP

Consider a polynomial time quantum circuit on $n$ qubits. The class of circuits under consideration encompasses the complexity class $\mathsf{BQP}$. Now, say we have an $n-1$ qubit polynomial time ...
BlackHat18's user avatar
  • 1,313
0 votes
3 answers
229 views

Mysterious behavior from QisKit's Aer Simulator MPS - how to fix it?

I'm running QAOA with a large number of qubits (64 qubits), and I'm having some issue getting the job to progress. I've tried a few different simulators, but I'm not sure how to tune the settings to ...
somewhere's user avatar
2 votes
0 answers
48 views

Quantum circuit runtime

I want to estimate the execution time of some experiments, and I would be interested to know how the time needed to run a quantum circuit grows in function of the number of qubits and the parametric ...
barrieta's user avatar
2 votes
0 answers
49 views

Quantum algorithms with few T gates?

Many existing quantum algorithms require millions or billions of T gates to reach a scale that is classically hard to simulate. However, existing Clifford + T circuits seem hard even with 100 or so T ...
shixian105's user avatar
5 votes
2 answers
289 views

Is that possible to simulate Grover's algorithm in quadratic time?

So it is clear that the Grover algorithm offers a quadratic speedup over the classical algorithms; my question is, is it known how to simulate Grover at the most quadratic time? To clarify my question,...
Dudu Ponar's user avatar

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