Questions tagged [pymatching]

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Stim: output decoded/predicted locations of Pauli errors

I created some Stim circuits to do circuit-level noise simulations of some Hyperbolic surface codes, and I was able to recover the thresholds in the literature. The detector error model is good at ...
edp23's user avatar
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3 votes
1 answer
152 views

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
1 vote
1 answer
84 views

How can we decode non CSS codes like XZZX code with Pymatching?

I am trying to use Pymatching to decode some non CSS codes like the XZZX code. Pymatching is a perfect decoder for CSS codes, which can work effectively even of a large code distance. I have tried to ...
Qingwei Wang's user avatar
1 vote
1 answer
51 views

How can I use surface code measurement data produced with Qiskit to run matching algorithms (e.g. PyMatching)?

I built a complex time-space dependent error model with Qiskit, and I am simulating surface codes with such error model to test their error correction capabilities. Qiskit supplies measurement data as ...
Marzio Vallero's user avatar
1 vote
2 answers
140 views

How to force PyMatching into the opposite equivalence class

PyMatching finds the minimum weight matching, which will belong to a particular equivalence class. But sometimes it is useful to know the minimum matching of each equivalence class. In the olden days, ...
James Wootton's user avatar
2 votes
1 answer
210 views

What is OBSERVABLE_INCLUDE in Stim and what is usefulness Pymatching

I have a question about the role of OBSERVABLE_INCLUDE within Stim circuits and how Pymatching uses it in order to decode syndromes. As far as I have understood from the documentation, ...
Antoni de Marti 's user avatar
0 votes
1 answer
80 views

Is it possible to adjust the weights of a pymatching graph after it is created?

I'd like to adjust the characteristics of a pymatching graph (specifically the edge weights of individual edges) to explore the effects on the decoding process. While the ...
Ian's user avatar
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0 votes
1 answer
70 views

Pymatching: Will starting with arbitrary weights affect the MWPM decoding process?

I am trying to examine the effect of weights on the performance of MWPM decoder on 5-repetition code as a simple example from Pymatching2. The idea is to vary the input weights by changing the error ...
Quantally's user avatar
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1 vote
1 answer
102 views

Using Pymatching to decode lattice surgery process

I want to simulate the error correction procedure for a CNOT gate on surface code and RHG cube, made by the lattice surgery process of "merge and split". In this case, the code has an H-...
Yaron Jarach's user avatar
1 vote
1 answer
125 views

How to compute Z logical operators of a toric code using Kunneth theorem?

I'm going through pymatching tutorial on constructing a toric code using hypergraph product of two repetition codes. The hypergraph product code construction $H G P\left(H_1, H_2\right)$ takes as ...
tomek's user avatar
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0 votes
0 answers
60 views

How can I decode errors in the multiple rounds of the surface code in pymatching?

The parity check matrix is 5x13. I run a distance three surface code with 3 rounds for each shot. The syndrome measurement results are as follows for the first shot: ...
quest's user avatar
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1 vote
0 answers
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Finding the number of Failure for Surface Code by using Pymatching (without STIM): ValueError: The shape of the syndrome vector z is not valid

I run the surface code for distance-3 with 3 round. I am now trying to decode and find the number of failures. My error probability of 0.08. Here are my syndrome results: ...
quest's user avatar
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0 votes
0 answers
18 views

View/Add unconnected nodes in PyMatching

I have a repetition code like below. Since I have no SPAM error, some detectors are unconnected nodes. I cannot see the nodes from pymatching.Matching.edges(), but I can see they exist in the graph ...
Jiakai Wang's user avatar
0 votes
1 answer
35 views

Pymatching: 'Matching' object has no attribute 'decode_batch'

I am trying to run the example from documentation: pymatching docs Here is my code: ...
quest's user avatar
  • 636
0 votes
1 answer
132 views

Using Deterministic Errors in Stim Detector Circuit and decoding with Pymatching: X_ERROR(1) failing in PyMatching

the Question Is there a standard way to use deterministic errors (so, for instance, X_ERROR(1)) in Stim with PyMatching? Currently, sometimes if I use ...
bumble13's user avatar
1 vote
1 answer
266 views

Can Stim and PyMatching analyze logical error rate of non-deterministic observable?

In Stim, logical observable has to be deterministic. To calculate the logical error rate, we compare the actual_observables sampled with stim circuit and ...
Jerry's user avatar
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0 votes
1 answer
238 views

How is the match graph extracted from a stim.circuit.detector_error_model?

Let's say we have an error mechanism error(0.1) D7 D8 ^ D9 D10 ^ D13 D15. I understand that Stim is trying to decompose the complex errors into graphlike errors. It ...
Jerry's user avatar
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0 votes
1 answer
186 views

Pymatching, Parity Check Matrix with Syndrome Measurements and Detection Events

I am running distance 3 surface code with 3 rounds: Here is the parity check matrix of X stabilizers for distance three surface code: ...
quest's user avatar
  • 636
4 votes
3 answers
319 views

Are there open source implementations of quantum error correction decoders?

To detect and correct for errors in a topological quantum memory (toric code for example) one needs a quantum error correction algorithm also known as decoder. The minimum weight perfect matching (...
francois-marie's user avatar
0 votes
1 answer
54 views

Do detection events mean temporal and spatial coordinates?

In pymatching, the check_matrix structure is for stabilizers rather than measurement outcome of stabilizers. I want to plot "matching" for my measurement outcomes.To do that, I need to ...
quest's user avatar
  • 636
3 votes
1 answer
72 views

Pymatching shows a large timing distribution to decode the same set of syndromes

I am interested in looking into histogram distributions of decoder timing for different syndrome inputs (sourced from stim) into pymatching. Unfortunately, it seems the histograms I product are more a ...
Ian's user avatar
  • 94
1 vote
1 answer
87 views

Using PyMatching for CSS code with more than two Stabilizers per qubit

I am implementing QEC cycles for CSS codes and using PyMatching for decoding. Since I can quickly obtain the parity-check matrix, PyMatching is convenient. However, when I try to use it for CSS codes ...
Unknown's user avatar
  • 53
0 votes
1 answer
111 views

Check_matrix in Pymatching and Understanding the Plot

In the simplest case, let's assume we have distance 2 surface code. The X stabilizers will be: X1X2X3 and X3X4X5 which is shown by the red lines. So the parity check matrix will be: $$ \begin{bmatrix}...
quest's user avatar
  • 636
2 votes
1 answer
98 views

PyMatching.Matching.decode() returns incorrectly sized array

I have having trouble getting the decode(...) function for a pymatching.Matching object to return an array of an appropriate ...
Ian's user avatar
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1 vote
1 answer
210 views

Pymatching Toric Code vs Surface Code

I am looking the example of toric code in Pymatching. Here is the code: ...
quest's user avatar
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