Questions tagged [error-mitigation]
For questions about QEM (Quantum Error Mitigation) which is different from Quantum Error Correction in that no extra qubits are used.
81 questions
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Correlated sampling of Pauli twirling operators
In standard treatments of randomized compiling, each gate layer is twirled with a twirling operator that is sampled uniformly at random from the Pauli group. Twirled gates can be combined modularly by ...
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Executing multiple calibration circuits on IBM real backend
I am testing a new algorithm for quantum error mitigation based on fuzzy clustering. As you can see in the piece of code below the calibration step is composed of multiple instances, that is I want to ...
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Error Mitigation in Dynamic Quantum Circuits: Alternatives to Dynamical Decoupling?
"I have a regular quantum circuit (i.e., not a dynamic one), let's call it qc. When I run it on a real quantum computer without using dynamical decoupling, the result is poor. However, when I ...
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Dynamic decoupling error mitigation
I am trying to understand dynamic decoupling error suppression. What are some python code and resources of qiskit related to dynamic decoupling supported on the ...
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How to estimate noisy expectation value in limit of infinite shots?
I suspect this is an obvious question, but it has proven surprisingly elusive!
Suppose I have a quantum circuit, as well as a pre-defined initial state. After performing this circuit, I evaluate an ...
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Are close states still close after measurement (regarding trace distance)?
We are given two states $|\psi_1\rangle, |\psi_2\rangle \in \mathbb{C}^2 \otimes \mathbb{C}^2$ with trace distance $\leq \varepsilon$, so they are very close to each other.
Now, assume we measure the ...
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What is the relation between Shor's code and the GHZ states?
The logical states for Shor's code $|0_L\rangle$ and $|1_L\rangle$ are
$$
\begin{equation}
\begin{aligned}
|0_L\rangle = \left(\frac{|000\rangle+|111\rangle}{\sqrt{2}}\right)^{\otimes{}3}\...
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Quantum Error Correction Difficulties: "Measurements destroy quantum information" Intuition
Context: In section 10.1.1, Nielsen and Chuang describe the difficulties QEC faces compared to classical error correction. Particularly that
Measurements destroy quantum information.
Shor states in ...
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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?
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What kind of quantum error is most likely to happen and are considered most in quantum error correction codes?
In quantum error correction literature, it is assumed that the possibility of happening a few-qubit error is bigger than a many-qubit error. Does this assumption have any physical evidence? I am ...
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Erasure errors in quantum error correction
Consider an $[n, k, d]$ classical code. This code can correct up to $d-1$ erasures. For example, if we have the code that maps $0\rightarrow 00$ and $1\rightarrow 11$, this code has distance $2$. ...
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Does qiskit make any rounding errors or anything similar, or is it a perfect (but slow) simulation of a quantum computer?
I ran the following circuit to calculate the real part of the Bargmann Invariant of a system of quantum states. The invariant is defined as
...
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ZNE for mitigating errors in probability distribution results
Can ZNE be applied to mitigate errors for getting the probability distribution in the computational basis rather than mitigating errors for calculation of expectation values?
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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 ...
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How does error accumulate when entangling two distant qubits with limited connectivity?
My goal is to minimize accumulated error when entangling two qubits that cannot be entangled via a single native two qubit gate operation.
I have a coupling map/graph for the qubits of an IBM quantum ...
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Qiskit's measurement error mitigation from counts data only, in 2023
Months or years ago, in a remote part of the globe, someone accessed an IBM Quantum computer online to perform a real experiment. She saved the resulting measurement outcomes of the algorithm in csv ...
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How to perform below operation in Qiskit?
I want to implement the below equation in Qiskit.
$(A \otimes B).\rho.(B^\dagger \otimes A^\dagger)$ where $\rho$ is a density matrix and $A$ and $B$ are CNOT gates.
$$ A=\begin{bmatrix}
1 & 0 &...
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Is there something like error-suppression codes?
My question is a bit on the soft side, and basically asks if there is something between error mitigation and full error correction?
On the one hand, as far as I understand, trying to increase the ...
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Where have the error mitigation utilities moved to in Qiskit?
Now that Qiskit Ignis has been deprecated where have the error mitigation utilities been moved to? I am unable to find that by doing a quick google search.
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Probabilistic error cancellation: how are we sure (i) the inverse noise *mathematically* exists, (ii) its expansion contains implementable operations
I am currently learning the basics of probabilistic error cancellation.
The idea, in summary, is the following:
We want to implement a quantum circuit having a noiseless (unitary) implementation $\...
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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 \...
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Bounds on success probability of an algorithm under depolarizing noise
The problem I have is that, I have a quantum circuit performing a certain task (e.g. Shor's algorithm) and the circuit is subject to depolarizing noise, Pauli errors, after each gate. And I want to ...
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how does one get native 2-body measurements?
How are Majorana-based architectures able to possess native 2-body measurement operations? Could anyone provide an appropriate reference explaining that?
Are those native measurement operations ...
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How to transform a qiskit quantum circuit to a braket circuit?
I have a quantum circuit in qiskit. Now I want to know is there any way that I can transform it to a braket circuit in AWS?
I want to use error mitigation in AWS. I have the circuit in qiskit. But as ...
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Measurement of readout errors for error mitigation algorithms
I am using an error mitigation algorithm that uses the readout errors p(0|1) and p(1|0) to correct the errors due to noise in my original circuit. I am trying to measure the readout errors in the same ...
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Qiskit, possible to manipulate mid-circuit measurement outcomes?
I'm currently coding up an error correction gadget using qiskit.
The one I'm doing now is 7-qubit Steane code with Steane's error correction gadget, in which the ancilla qubits are measured and then ...
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How is randomized compiling actually helpful: experimentally, a gate is not "perfect" followed by some noise acting "after"
I am currently learning randomized compiling with this paper which seems to be the "main" reference on this topic (at least many papers refer to this one).
However, I do not understand how ...
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What do the 'resilience_level's in qiskit-runtime's primitives mean?
The qiskit-runtime primitives programs 'estimator' and 'sampler' for accessing the IBM Q hardware have the option of error mitigation by setting the 'resilience_level'.
Here an overview of the meaning ...
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How is Pauli twirling applied to a noisy gate in practice?
My understanding of Pauli Twirling mainly comes from this paper. Please, correct me if I am wrong in any part of my explanation.
General idea of Pauli twirling
The idea of Pauli Twirling is the ...
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Time Complexity (Big O Notation)
What is the time complexity of the two error-mitigation methods that are implemented in qiskit.ignis.
1- pseudo inverse.
2- least squares.
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Which error channel definitions should I use if I want to compare the performance of a QEC protocol for depolarizing errors vs dephasing errors?
Let's say you want to investigate if a quantum error correction or error mitigation protocol performs better under dephasing errors compared to depolarizing errors, or if a quantum algorithm is more ...
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Does anybody know what a low-degree Markov field is?
In the paper Fast Estimation of Sparse Quantum Noise I saw the following description:
quantum devices approaching the fault-tolerant regime will have very
few significant errors (and therefore are ...
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Are there any systematic tools for estimating expected error rate?
Like we all probably know, today’s NISQ computers are, as their name implies - very noisy. Hence, if we desire to obtain valuable results then we should come up with circuit designs that minimizes the ...
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Best tutorial about the variational quantum eigensolver (VQE)
I want to find a tutorial on VQE with a good valance between the theoretical background of the method, and it's working implementation on QPU. Covering advanced topics such as quantum error ...
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Is there a tutorial for error mitigation in qiskit that does not use the deprecated ignis?
Working through the qiskit text I have come accross measurement error mitigation a few times (Measurement Error Mitigation, Lab 3: Quantum Measurment,...]. In the online textbook the coding indicates ...
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What is more important, minimizing the number of gates, or the number of qubits?
I am new to the quantum world, and I have 2 circuits that measure cosine similarity between 2 binary vectors. One uses a swap test, the other uses something called a hyper-state generation procedure.
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What is the difference between Error Mitigation (EM) and Quantum Error Correction (QEC)?
From what I understood, EM is mostly post-processing and does not affect quantum circuit complexity whereas QEC has overheads and integrates as part of a quantum circuit. Is this correct?
Also, which ...
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Options for more complex error models on stim?
We're trying to simulate whether some initialization strings are preferable to others. For example, would initializing all qubits to $|0\rangle$ lead to a lower error rate?
Is it possible to further ...
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What is the concrete difference between qiskit thermal_relaxation_error and phase_amplitude_damping_error?
What is the concrete difference between those two error models in qiskit.providers.aer.noise?
For phase_amplitude_damping_error ...
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Readout Error in Qiskit: What is a reasonable model?
The Readout Error in Qiskit is described here: https://qiskit.org/documentation/stubs/qiskit.providers.aer.noise.ReadoutError.html
Although it is easy to obtain such an error for 1-qubit for IBMs ...
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Implementing Readout Error in my circuit seems to have no effect whatsoever
I am trying to perform a simulation using Qasm in order to see how the readout error actually affects my circuit. The circuit I am implementing is a trivial one, the three qubit one that implements ...
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How to set the meas_level and optimization_level in Quantum Azure IonQ provider?
I am performing a benchmark process using the Azure Quantum IonQ provider. I use Qiskit in the Azure platform, and I was trying to see how to control the transpiling and compiling process. It seems ...
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Can ancilla-based parity measurements be used to detect errors in NISQ algorithms?
Measuring stabilizer eigenvalues is a fundamental part of quantum error correction. However, I was wondering if the idea of measuring a stabilizer using an ancilla could be useful in other contexts as ...
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Surface Code Eigenstates as Circles
I learned that logical $|0\rangle$ of surface code, is an eigenstate, where all stabilizers are +1 value, and since the z-stabilizer is enforcing an even amount of edged in each node, and the x-stab ...
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Code Length of most Naive Repetition Code
What is the formula or answer to the following coding: I would like to get logical qubit with logical error rate of $P_L=1E-10$ or $P_L=1E-19$ for Shor's algorithm, but I would like to know how many ...
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Add noise_model when using 'ibmq_qasm_simulator' backend and provider.runtime.run() function
I am trying to test some qiskit code that employs readout-error mitigation using the ibmq_qasm_simulator backend and Qiskit Runtime. I am getting the backend as ...
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Qubit State (theta,phi) Dependence on the Readout Error
Do the readout errors on the publicly available IBM quantum computers have any dependency on the state being measured? That is, if we are measuring a qubit in the state
$\cos({\theta/2}) |0> + e^{i\...
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Surface Code - Convert Control Error to Clifford Error
I am simulating surface code, in order to find the logical error as a function of control error in my circuit.
Each of my data qubits is multiplied in control error = a unitary matrix $U$ which is ...
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How to calculate the number of qubits in surface code, for given physical error rate
I am working on improvement of physical qubit error probability.
I would like to know: how to calculate the size I need for surface code, given that I need that the logical error probability will be ...
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Why does making a quantum circuit more noise resilient make it easier to simulate classically?
I was reading Quantum Computing in the NISQ era and beyond (John Preskill, 2018) but I didn't get this point on pages 9-10:
There is a substantial opportunity for experimentalists and theorists, ...
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