Questions tagged [noise]

For questions about different types of noise a quantum computer (or qubits) may experience; how this affects the outcome of the computation; how to reduce a specific type of noise on a specific implementation of quantum computer; or how to simulate noise.

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Practical implementation of Shor and other factoring algorithms

I explore the realm of open-source quantum computers, particularly those available in the current or near-term future. My goal is to implement the largest possible integer factorizations. I would ...
ali khosravi's user avatar
1 vote
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Is this quantum circuit design more prone to noise?

I am designing a quantum circuit which uses one qubit as the control of many $\text{CSWAP}$ operations. And then, this qubit will be measured. Will the result be more prone to noise since all the ...
Deren  Liu's user avatar
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VQLS behaves badly under simulation with noise

I was studying VQLS in https://qiskit.org/textbook/ch-paper-implementations/vqls.html and since I could not understand the circuit created by the new Hadamard test (...
MrEightL's user avatar
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How to model the IBM quantum errors?

I'm conducting a study of the quantum channel errors, and a question has arisen: Is it possible to model the errors of an IBM quantum computer with Kraus operators?
Leandro Matheus Morais da Silv's user avatar
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Using Noise Model of a real hardware on qiskit simulators

I am trying to understand how to use the noise model of real hardware. Below is the part of the code I have written with the help of sample codes from these links: qiskit.github.io/qiskit-aer/apidocs/...
Manu's user avatar
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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
4 votes
1 answer
603 views

Why is it not a good idea to run Shor's algorithm on a big noisy quantum computer?

Suppose I try to run Shor's algorithm on a big noisy quantum computer. For a given input I repeat the circuit many times and collect statistics for the measurements of each qubit. Now based on the ...
Frederik Ravn Klausen's user avatar
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40 views

How is coherent noise more detrimental than incoherent noise for QEC when QEC is supposed to decohere noise?

It's sometimes mentioned that unitary, coherent, noise can adversely impact the performance of QEC codes compared to purely stochastic Pauli noise. This motivates protocols such as randomized ...
jfids's user avatar
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Qiskit Noisy simulator sample code or documentation

I have to run some quantum circuits on Noisy simulator of qiskit? I tried searching some noisy simulator of qiskit but could not find anything. It would be great if someone can direct me to a qiskit ...
Manu's user avatar
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1 answer
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Are there sources of noise in qubits for which the fundamental origin is unknown?

I am looking for examples of sources of noise in qubits for which the fundamental origin is unknown. I.e. we see experimentally that the qubits are noisy, but we do not really understand why they are &...
Marco Fellous-Asiani's user avatar
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Completeness relation of kraus operators not satisfied in Fake backends

With the following code ...
stopper's user avatar
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Error on expectation value even with zero noise

If I use V2 fake backends, I can set a certain noise equal to 0 with backend.target['measure'][(0,)].error = 0 and I can do that for each kind of instruction ('id',...
stopper's user avatar
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1 answer
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Clarification on Definitions of Relaxation Probabilities

In the paper Modelling and Simulating the Noisy Behaviour of Near-term Quantum Computers, when the authors discuss relaxation times ($T_1$), they define two probabilities, $P_{T_1}$ and $p_{\text{...
banercat's user avatar
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1 answer
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Can Noise in measurements lead to non-zero probability of a state that was not originally in the state vector?

Consider the following state vector $$\frac12 (|000\rangle + |011\rangle + |101\rangle + |110\rangle)$$ Can noise in measurements lead to a non-zero possibility of measuring the state $|111\rangle$ ...
yousef elbrolosy's user avatar
2 votes
0 answers
109 views

Improve accuracy of fake backends while remaining realistic

If I run the code backend = FakeLima() nm = NoiseModel.from_backend(backend) print(nm.__dict__.keys()) I get the following output: ...
stopper's user avatar
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0 answers
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How is Pauli twirling so powerful?

So the Pauli twirling approximation gives us a quantum channel $\Phi$ that transforms a density matrix $\rho$ to: $\Phi(\rho)\mapsto\sum_{i=0}^3 \sigma^i \rho \sigma^i,$ where $\sigma^0 = \mathbb{I}, \...
JoJo P's user avatar
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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
2 votes
2 answers
90 views

What are efficient methods for measuring gate noise?

In this question I'm concerned with getting detailed spectral information about analog noise in quantum gates. Assume we have imperfect control over transitions between $\vert 0\rangle$ and $\vert 1\...
Dr. T. Q. Bit's user avatar
1 vote
0 answers
251 views

Is there a way to implement a noisy CNOT gate using CUGate in Qiskit

Wondering if there's a way to implement the noisy version of CNOT (or CX) gate via CUGate using qiskit library for a given fidelity p?
codeit's user avatar
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3 votes
1 answer
102 views

What are overlooked noise sources in circuit-level noise?

In the research of quantum error correction, noise is often classified into code capacity noise, phenomenological noise, and circuit-level noise. Among these, circuit-level noise is considered the ...
david's user avatar
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2 answers
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What is the clear definition of coherent versus incoherent errors?

The noise types in quantum computing are pivotal topics frequently discussed in academic papers. Could you provide a clear definition of coherent versus incoherent errors? Additionally, I'm keen to ...
Yunjie Wang'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
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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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How can one obtain all calibration data which is needed to plot error_map of the ibm backend from few month ago?

I want to plot the error map of an IBM Quantum backend from the calibration data I saved a month ago. The saved file just contain qubit properties and to plot error map I would need all information ...
Shil S's user avatar
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2 answers
93 views

How can visualise the old error map of Ibm backend if one save the calibration data of the backend at that time?

I have the calibration data of an Ibm backend and now I want to plot the error map of the device at that specific time. How can I do this?
Shil S's user avatar
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0 answers
18 views

Qiskit Aer Noise Module

I am trying to use the following single qubit depolarizing channel (on a GHZ state for example) but the simulation histogram counts are not affected ...
Sami Farrag's user avatar
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1 answer
57 views

RB with Clifford: can I define my own random model?

I'd like to know how much freedom I have when setting up an RB Clifford model. Is any Clifford circuit sample ok for benchmarking (as long as it characterizes the Clifford group)? What are the ...
Daniele Cuomo's user avatar
1 vote
1 answer
112 views

How to run Color code on STIM?

I am trying to simulate color code on STIM. I have provided my code below. But I am getting the following error ...
Subrata Das's user avatar
1 vote
0 answers
48 views

How to manipulate thermal relaxation noise in Qiskit model?

I am trying to experiment with various values of T1 and T2 parameters in thermal relaxation noise. ...
bisarch's user avatar
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0 votes
0 answers
35 views

Impact of various kinds of noise on calculation of operator's expectation value

I am trying to calculate the expectation value of an operator Op on Qiskit's simulator with noise present. I am trying to study the impact of various kinds of ...
bisarch's user avatar
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1 vote
0 answers
99 views

What does adding depolarizing error on a Hadamard gate mean mathematically?

I have a quantum circuit as the following picture. Now I add the depolarizing error on the Hadamard gate using the following code in Qiskit. ...
Michael.Andy's user avatar
1 vote
1 answer
94 views

G-twisted Pauli twirl circuit

Pauli twirls are obtained by taking a unitary $U$, and finding some Pauli gates $P_1, P_2$ such that $P_1 U P_2$. So, for example, one possible twirl of the $S$ gate would be $YSX$. In the paper ...
epelaez's user avatar
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1 vote
1 answer
133 views

Mathematical justification of postprocessing in QRNG

I have reading about Quantum Random Number Generators (QRNGs), and it seems that usually classical post processing is applied to the initial output of the quantum circuit to: improve the quality of ...
Martin Hurtado's user avatar
2 votes
0 answers
38 views

Exploiting virtual-$Z_{\theta}$ corrections in QEC

The work done by IBM Researchers to perform virtual-$Z_{\theta}$ gates allowed them to: achieving zero-time relative phase shifts; correcting $Z_{\phi}$ errors occurring when applying some gates -- e....
Daniele Cuomo's user avatar
1 vote
1 answer
94 views

How many measurements are required to resolve data with a given fidelity?

From Google's quantum supremacy paper Having found the error rates of the individual gates and readout, we can model the fidelity of a quantum circuit as the product of the probabilities of error-...
bubakazouba's user avatar
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0 answers
42 views

Representing 1 qubit pauli-channels as an averaging effect of random rotations in the bloch sphere. Basic literature?

I am looking into 1 qubit pauli channels, e.g. the dephasing channel $$\mathcal{E}(\rho)=(1-p)\rho+p\sigma_z\rho\sigma_z.$$ I found out it could be represented as $$\mathcal{E}(\rho)=\int p(\lambda)\...
manuel459's user avatar
  • 201
3 votes
1 answer
74 views

What is the explicit form of $T_1$ decay channel?

I see $T_1$ error mentioned in many experimental papers (for example, page $10$ of this paper mentions such a decay.) How do I model $T_1$ decay theoretically? More concretely, here's my question. Say ...
BlackHat18's user avatar
  • 1,313
0 votes
1 answer
167 views

Comparing the Erasure and Depolarizing Noise Channels in QEC

Are there any quantum error-correction codes which have been found to exhibit high thresholds for either Pauli-based depolarizing noise or Erasure noise channels, but not for both? Are there reasons ...
MatthewS1990's user avatar
2 votes
1 answer
75 views

Upper bounding the trace distance between a noisy and noiseless quantum state

Consider a quantum state $$ \rho = \begin{pmatrix} \rho_{00} & \rho_{01} \\ \rho_{10} & \rho_{11} \\ \end{pmatrix}. $$ Now, consider the effect of the amplitude damping noise $\mathcal{N}$ of ...
BlackHat18's user avatar
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0 votes
0 answers
175 views

How can I perform syndrome measurements for both X-type and Z-type stabilizers in Stim?

I would like to simulate the logical error rate of the surface code under depolarizing noise using Stim. The decoder I am using decodes from both X-type and Z-type stabilizer syndrome values. ...
lan's user avatar
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0 votes
1 answer
110 views

What is the Stim color_code:memory_xyz circuit executing?

In Stim's color_code:memory_xyz, the all data qubits are first initialized to the |0> state, then the Z-type stabilizer measurement circuit is executed, and ...
lan's user avatar
  • 51
1 vote
1 answer
94 views

Is there a way to perform two simulations with the same noise in Stim?

I would like to calculate the logical error probabilities of surface codes under depolarizing noise using Stim. In doing so, if all data qubits are initialized to |0>, it is not possible to account ...
lan's user avatar
  • 51
2 votes
1 answer
162 views

Is it possible to get access to the old noise model from a few months ago for Ibmq backends?

I performed an experiment on a real Ibmq backend, and the results were satisfactory. I now require the simulation of that experiment. The simulation is not sufficiently consistent with the old ...
Shil S's user avatar
  • 27
0 votes
1 answer
124 views

How can I determine if the error correction by estimated error results in a logical error in circuit-level noise?

I am trying to simulate the logical error probability of color code under circuit-level noise. In the code capacity noise and the phenomenological noise, the Pauli errors to the data qubits that occur ...
lan's user avatar
  • 51
0 votes
1 answer
289 views

How can I extract actual Pauli error in Stim?

I am using a quantum circuit simulator "Stim" to simulate the logical error probability of color code under circuit-level noise. In the code capacity noise and the phenomenological noise, ...
lan's user avatar
  • 51
1 vote
0 answers
78 views

Zero noise extrapolation for error mitigation: Meaning of rescaled density matrix, specifically when there is no local hamiltonian evolution

I have a few questions regarding dynamics rescaling for zero noise extrapolation. In the paper Error mitigation for short-depth quantum circuits, in equation (30), they write We redefine $T \...
lost forgotten pearl's user avatar
2 votes
1 answer
423 views

How to get a noisy density matrix after partial measurements in Qiskit

I'm trying to study the effect of noise on a quantum system with partial measurements using Qiskit. Suppose I have $N + M$ qubits and I run a quantum circuit and measure $M$ of them. I want to know ...
Germ's user avatar
  • 315
1 vote
1 answer
231 views

Is there any map between Phenomenological Noise Model and Circuit Based Noise Model?

In the phenomenological noise model, we have an approximately 2% error threshold in surface codes. In the circuit-based noise model, the threshold ranges from 0.5% to 0.7%. I'm curious if there's a ...
quest's user avatar
  • 636
3 votes
2 answers
278 views

Converting $T_1$ and $T_2$ decay rates to noise supported by stim

Stim only supports Pauli noises like DEPOLARIZE1, DEPOLARIZE2, X_ERROR, ...
sl_'s user avatar
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3 votes
1 answer
1k views

Is it possible to use fake backends to run Qiskit Runtime primitives?

I have the following code to run an Estimator primitive by using Qiskit Runtime. It computes the expectation value $\langle O \rangle = \langle \psi | O | \psi \...
SimoneGasperini's user avatar

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