Eigenstate thermalization hypothesis (ETH) code[1]

Description

Also called a thermodynamic code [2]. An \(n\)-qubit approximate code whose codespace is formed by eigenstates of a translationally-invariant quantum many-body system which satisfies the Eigenstate Thermalization Hypothesis (ETH). ETH ensures that codewords cannot be locally distinguished in the thermodynamic limit. Relevant many-body systems include 1D non-interacting spin chains, Motzkin chains, or Heisenberg models.

ETH requires that for ordered energy eigenstates \(|E_l\rangle\) and any local observable \(O\), \begin{align} |\langle E_l|O|E_l\rangle-\langle E_{l+1}|O|E_{l+1}\rangle|\leq\exp(-cn) \end{align} for a constant \(c\). This implies that energy eigenstates around some energy \(\bar E\) are approximately locally indistinguishable from one another, as their reduced density matrices on any subsystem are both approximately thermal at energy \(\bar E\). In this way, global information is protected from local measurements by the environment as \(n\to\infty\).

Protection

Approximately protects against erasure errors at known locations. Translation invariance alone is sufficient for good approximate error-correcting properties in a many-body spectrum, including in integrable models [1]. The ETH code generated from the spectrum of the translation-invariant 1D Heisenberg spin chain [1] has recovery infidelity (against the erasure of a constant number of sites) scale as \(\epsilon_\text{worst}=O(1/n)\) [2].

Decoding

An explicit universal recovery channel for the ETH code is given in [3].

Parents

Cousin

  • Topological code — ETH codewords, like topological codewords, are locally indistinguishable.

Zoo code information

Internal code ID: eth

Your contribution is welcome!

on github.com (edit & pull request)

edit on this site

Zoo Code ID: eth

Cite as:
“Eigenstate thermalization hypothesis (ETH) code”, The Error Correction Zoo (V. V. Albert & P. Faist, eds.), 2022. https://errorcorrectionzoo.org/c/eth
BibTeX:
@incollection{eczoo_eth, title={Eigenstate thermalization hypothesis (ETH) code}, booktitle={The Error Correction Zoo}, year={2022}, editor={Albert, Victor V. and Faist, Philippe}, url={https://errorcorrectionzoo.org/c/eth} }
Permanent link:
https://errorcorrectionzoo.org/c/eth

References

[1]
F. G. S. L. Brandão et al., “Quantum Error Correcting Codes in Eigenstates of Translation-Invariant Spin Chains”, Physical Review Letters 123, (2019). DOI; 1710.04631
[2]
P. Faist et al., “Continuous Symmetries and Approximate Quantum Error Correction”, Physical Review X 10, (2020). DOI; 1902.07714
[3]
N. Bao and N. Cheng, “Eigenstate thermalization hypothesis and approximate quantum error correction”, Journal of High Energy Physics 2019, (2019). DOI; 1906.03669

Cite as:

“Eigenstate thermalization hypothesis (ETH) code”, The Error Correction Zoo (V. V. Albert & P. Faist, eds.), 2022. https://errorcorrectionzoo.org/c/eth

Github: https://github.com/errorcorrectionzoo/eczoo_data/tree/main/codes/quantum/qubits/eth.yml.