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sustainability threshold
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valbert4 committed Nov 8, 2023
1 parent cd39da4 commit 3bc5517
Showing 4 changed files with 11 additions and 4 deletions.
2 changes: 1 addition & 1 deletion codes/quantum/groups/rotors/stabilizer/rotor_5_1_3.yml
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@@ -25,7 +25,7 @@ relations:
- code_id: small_distance
cousins:
- code_id: qudit_5_1_3
detail: 'The five-rotor code is a bosonic analogue of the five-qudit code.'
detail: 'The five-rotor code is a rotor analogue of the five-qudit code.'



9 changes: 8 additions & 1 deletion codes/quantum/properties/block/single_shot.yml
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@@ -38,7 +38,14 @@ description: |
features:
threshold:
- 'Residual errors do not become unwieldy after some system-size-independent number cycles of faulty syndrome measurements, and a perfect decoder would be able to recover the information if the final residual error is correctable.
The physical error rate below which the infidelity after perfect decoding decreases superpolynomially with system size is called the \textit{sustainable threshold} \cite{arxiv:2009.11790}.'
Consider acting on a state \(\rho\) with a noise channel \(\mathcal N\) with noise rate \(p\), followed by \(t\) rounds of noisy syndrome measurements \(\mathcal R\) with noise rate \(\eta\) and one perfect recovery (which can be substituted with destructive physical-qubit measurements in practice).
The failure probability of a single-shot code should decrease exponentially with the distance of the code,
\begin{align}
fp_{\text{fail}} =1-F\left(\mathcal{R}[\mathcal{R}_{\eta}\mathcal{N}_{p}]^{t}(\rho),\rho\right)
=t\left(p/p_{\star}\right)^{d}For p<p_{\star}~,
\end{align}
where \(F\) is a state fidelity, and where \(p_{\star} is called the \textit{sustainable threshold} \cite{arxiv:2009.11790}.
For any \(p\) below this threshold, there exists some maximum measurement noise \eta_{\star} that can be tolerated.'

relations:
parents:
2 changes: 1 addition & 1 deletion codes/quantum/qubits/dynamic_gen/da/floquet_color.yml
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@@ -12,7 +12,7 @@ introduced: '\cite{doi:10.26081/K6F65V,arxiv:2210.02468,arxiv:2212.00042}'

alternative_names:
- 'CSS Floquet toric code'
- '\(\mathbb{Z2}\) Floquet code'
- '\(\mathbb{Z}_2\) Floquet code'
- 'CSS honeycomb code'

description: |
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@@ -102,7 +102,7 @@ features:
Circuits can be optimized to specific architectures \cite{arxiv:2302.02192} using spacetime circuit codes and ZX calculus \cite{doi:10.1007/978-3-540-70583-3_25,arxiv:0906.4725}.'

decoders:
- 'Syndrome measurements are distance-preserving because syndrome extraction circuits can be designed to avoid hook errors \cite{arxiv:quant-ph/0110143}.'
- 'Using data from multiple syndrome measurements prior to decoding allows for correcting syndrome measurement errors. Syndrome measurements are distance-preserving because syndrome extraction circuits can be designed to avoid hook errors \cite{arxiv:quant-ph/0110143}.'
- 'Expanding diamonds decoder correcting errors of some maximum fractal dimension \cite{manual:{Andrew Landahl, private communication, 2023}}. The sub-threshold failure probability scales as \((p/p_{\text{th}})^{d^\beta}\), where \(p_{\text{th}}\) is the threshold and \(\beta = \log_3 2\).'
- 'MPE decoding is \(NP\)-hard in general \cite{arxiv:2309.10331}.'
- 'ML decoding \cite{arxiv:quant-ph/0110143} is \(\#P\)-hard in general \cite{arxiv:2309.10331}, but an approximate version takes time of order \(O(n^2)\) under independent \(X,Z\) noise for the surface code \cite{arxiv:1405.4883}.'

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