Questions tagged [stim]
For questions about Stim, the open source tool for high-performance simulation of quantum stabilizer circuits.
166
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Bug in stim HERALDED_PAULI_CHANNEL_1?
Tried this simple example where initializing two qubits in $|0\rangle$ state, performing biased bit flip erasure on qubit 1 using HERALDED_PAULI_CHANNEL_1 while ...
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How to get line fits from sinter.plot_error_rate to calculate logical error rate as function of physical
I would like to print the gradient and intercept values for the line fits generated by sinter.plot_error_rate.
My goal is that I'm trying to find logical error rate as a function of physical error ...
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Can we get which error mechanisms acutually happens in Stim?
I'm working on making some decoders for surface codes.
I know there is a great stabilizer simulator, Stim, so I try using it.
Now, I have a question: can we get what type of error mechanisms actually ...
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How to convert stim encoder circuit to a parity check matrix?
I would like to take an encoding noiseless circuit and output the corresponding parity check matrix in the the binary symplectic format $(H_x | H_z)$
I'm aware of the related question: How to get ...
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How to properly generate circuit measurement results from detector error model
I'm reading the paper of Google's neural network decoder for surface code, and I'm confused about how to generate the measurement results for pre-training dataset.
If I understand it correctly, the ...
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How to decompose pauli operator into the product of stabilizers in stim?
In stim, is there an easy method to decompose a Pauli operator into a product of stabilizers in the group $\langle S \rangle$? I can achieve this by performing Gauss-Jordan elimination manually, but I ...
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Stim error when measuring detectors
I am attempting to compute the circuit for the syndrome extraction of the [[144, 12, 12]] code using stim so as to consider circuit-level noise. Unfortunately, when trying to obtain the detector error ...
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feedback based on multiple measurments
I know that Stim has the option to play a conditioned pulse based on a previous measurment by writing CZ rec[-1] 1 which does a Z gate on qb1 if the last measurment ...
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49
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Get the amplitude of a computational basis in stim
How can I get the amplitudes of a specific computational basis state in stim?
I have looked into the stim.TableauSimulator which has a method ...
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Sample detection events with TableauSimulator
I've been manually driving stim.TableauSimulator to simulate more complex noise models like in a previous post.
The way I've set up my code is to replace instances ...
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How to apply rotation about X and Z in stim?
I have a quantum circuit illustrated in the provided image, where I perform a series of quantum operations followed by a projective measurement..
Using Qiskit, I've already written the code for this ...
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Whether/How can I combine logical error rates of the same circuit from different batches of samples in stim
Using one seed to generate one batch of sample and then compute the logical error rate is obviously statistically safe.
But in case I want to sample one small batch at a time, how can I configure the ...
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Use stim to simulate multiple different circuits with `shots=1` for each circuit
It is blazingly fast to sample a lot of shots from a single circuit with stim. However, I want to sample a singe shot for lots of different circuits(circuit strings)...
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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, ...
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Implementing a simple time-correlated error model in Stim
I'm aware Stim doesn't have the best capability for sampling arbitrary time-correlated errors. I was wondering what would be the best way to hack together the basic error model:
Before each round, ...
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How to use surface codes on a quantum circuit?
So far, I have used surface codes on Stim simulations only. The simulation is for a surface code and I want to understand how surface codes work when I comes to quantum circuit. How is this done for a ...
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Y observable from surface code in Stim
I understand that, in the surface code, it is generally harder to measure $Y_L$ compared to $X_L$ or $Z_L$, and code deformations are generally required. However, is there an easier way to calculate ...
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Why does Stim/PyMatching evaluate the threshold error rate differently for even and odd distances?
For the toric code, the threshold error rate value for no measurement errors should be around $p_{th}\approx 0.109$. If simulated with even distances, one finds that this is true. However, when I ...
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How can we know the expected value of data errors in Stim?
In Stim, after performing syndrome measurements circuit using stabilizer codes like surface codes, how can we know the expected value of errors occurring on each data qubit? Even if there are no ...
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Simulating erasures with stim
We're trying to simulate erasure errors on the surface code using Stim. The threshold for erasure errors on the data qubits (after initialization) is 50%.
We followed the following post: How do I ...
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Efficiently computing weight enumerators of quantum codes
Are there any packages that efficiently compute weight enumerators (and dual weight enumerators) of quantum error correcting codes?
I'm interested in a general method that works for both stabilizer ...
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Why does adding a 50/50 Z error after every initialization, reset and measurement account for randomness of outcomes in Stim?
Stim generates multiple (say N many) noisy samples by first collecting one reference sample, then running a Pauli frame simulator N times to track which errors may flip which measurements and ...
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How to get parity check matrix from a circuit in stim
I am working on QECC and, differently from classical ECC where everything is generally described by the parity-check matrices, QECC generally involves the low-level description of the circuit instead, ...
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Implementing biased erasure error in stim
We are trying to simulate the erasure channel in stim, but it is a biased erasure - meaning that the replaced qubit doesn't have a depolarizing channel but a biased channel.
We saw that there is a ...
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About detectors after final round of surface code
Stim's surface code implementation example includes additional detectors after the final round to measure data qubits.
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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
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How to pass multiple arguments to sinter plot --filter_func?
I'm using stim and sinter and can't figure out how to pass multiple arguments to sinter plot --filter_func. A single argument works as
...
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OBSERVABLE_INCLUDE in the REPEAT instruction in Stim
Can I increment the value of 'i' in OBSERVABLE_INCLUDE(i) for each iteration within REPEAT in Stim? For example, I would like the 'i' in OBSERVABLE_INCLUDE(i) to become 0,1,2,3,4,5,6,7,8 when the ...
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Effect of too many syndrome measurement cycles on surface code threshold
Assume I have a surface code with distance $d$ and an i.i.d error model with both single qubit depolarization and measurement errors, both with probability $p$.
In this case, one usually repeats the ...
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Emulating repetition code data subsampling
In google's repetition code memory experiment, they use the subsampling technique to reduce the experimental burden of acquiring data and enforce the self-consistency in error rates.
When I use ...
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Simulating a small distance surface code with individual qubit addressing
I want to simulate a small-distance surface code with either STIM or Qiskit. I want individual control over all the qubits (including the ancillas) to induce controlled errors in my circuit. I want to ...
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Node num_detectors + 1 in detector_error_model_to_pymatching_graph
I understand that the node num_detectors is the boundary node, but what's the use of node num_detectors + 1? The code is from the honeycomb boundary paper. What are spandrels?
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PAULI_CHANNEL_2 decomposition with zero prob for single qubit cases
Why does the code associated with the paper "Benchmarking the Planar Honeycomb Code" set some PAULI_CHANNEL_2 errors to tiny values?
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Intuition behind Stabilizer Tableau Simulation in Stim
I'm looking through section 4 of the Stim Paper and am having trouble understanding two points:
Why is it okay to insert Hadamards and random Xs at the beginning of computation and Hadamards? In the ...
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Zx graphs in Stim
It is possible to create an ASCII graph in Stimzx for a ZX calculus diagram.
I would like to create something like this
but I cannot seem to recreate the correct ASCII format. When I do something ...
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Why is the error propagation by the CNOT gate considered without taking into account the state?
In the syndrome measurement circuit of a stabilizer code, I think you would consider that Pauli errors propagate through the CNOT gates. I don't understand why one usually considers the propagation of ...
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Inbuilt Stim circuits showing unexpected Memory X and Memory Z logical error rates for unrotated surface code
When running memory experiments using Stim’s inbuilt unrotated surface code circuits to generate thresholds, I am getting the opposite behaviour to the rotated surface code for memory X and memory Z ...
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Stim and pickle/dill incompatibility
I have been using pickle (and also tried dill) to save and load Clifford gates coming from the Stim library. The following code:
cliff_list = dill.load(filename)
...
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76
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Commutation relationship and measurement results
There are things I do not understand about the following circuit, and I would appreciate it if you could explain.
...
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Inverted memory X and memory Z logical error rates for unrotated surface code in Stim?
The circuit which measures a Z-type stabilisers in the surface code is:
whereas for X-type stabilisers it's:
Both types of stabilisers are measured in a memory experiment in the inbuilt surface code ...
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Handling lots of data points in Sinter Graphing
Sinter is really awesome for streamlining my circuit runs. It was incredibly easy to set up and switch into, and it's very fast. The save_resume_filepath is a life ...
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Correctability of X, Y, and Z Errors in Quantum Surface Codes and Color Codes
In surface codes and color codes, when the code distance is $d$, you can correct up to $[(d-1)/2]$ Pauli errors. I would like to know what this $[(d-1)/2]$ Pauli errors means for $X$, $Y$, and $Z$. ...
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Stim: Implementing lattice surgery
This is an understanding check more than an actual question. Implementing lattice surgery has already been discussed on the forum: How to implement lattice surgery in stim? -- I'm just trying to make ...
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47
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Sinter: save detection counts
Is there a way to extract all detection events (for each detector individually) that occur during a sinter.Task/sinter.collect ...
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What's hook error in surface code?
this line of c++ in surface code generation says:
// Define interaction orders so that hook errors run against the error grain instead of with it.
So how does the interaction orders in surface code ...
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How to resolve ValueError: The circuit contains non-deterministic observables
I constructed a part of the syndrome measurement circuit as follows using Stim. However, when I run dem = circuit.detector_error_model() and ...
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Are there qiskit or stim examples of how to decode a subsystem code
I can manage decoding a stabilizer code in qiskit and stim. I'd like to try a subsystem code next. For a stabilizer code, all stabilizers commute so simultaneous measurement of these produces ...
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Differences in Simulating Syndrome Measurement Circuits with Prepared States : $|0_L \rangle$ vs $|0\rangle^{\otimes n}$
In the syndrome measurement circuit constructed using Stim, is there any difference between simulating with the data qubits prepared in the state $|0_L \rangle$ and simulating with data qubits ...
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Modelling correlated measurement errors in Stim
Is there a way to model correlated measurement errors in Stim? I see we can implement correlated Pauli errors, but couldn't find anything for correlated measurement errors.
