Two-block quantum code[1] 

Also known as Two-square-block code.


Galois-qudit CSS code whose stabilizer generator matrices \(H_X=(A,B)\) and \(H_Z=(B^T,-A^T)\), are constructed from a pair of square commuting matrices \(A\) and \(B\).

Generalized constructions utilizing more than two blocks have also been considered [2].


Code parameters are generally unknown, although they can be formally expressed in terms of ranks of some matrices related to \(A\) and \(B\). The corresponding expressions, as well as some upper and lower bounds on parameters are given in [3].




  • Quantum low-density parity-check (QLDPC) code — When matrices \(A\) and \(B\) have row and column weights bounded by \(W\), a two-block quantum code is a quantum LDPC code with stabilizer generators bounded by \(2W\).
  • Lifted-product (LP) code — LP codes can be constructed using non-square matrices and taking a hypergraph product over a group algebra, while two-block quantum codes are constructed directly using square matrices.


A. A. Kovalev and L. P. Pryadko, “Quantum Kronecker sum-product low-density parity-check codes with finite rate”, Physical Review A 88, (2013) arXiv:1212.6703 DOI
M. Borello et al., “Dihedral Quantum Codes”, (2023) arXiv:2310.15092
H.-K. Lin and L. P. Pryadko, “Quantum two-block group algebra codes”, (2023) arXiv:2306.16400
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Zoo Code ID: two_block_quantum

Cite as:
“Two-block quantum code”, The Error Correction Zoo (V. V. Albert & P. Faist, eds.), 2023.
@incollection{eczoo_two_block_quantum, title={Two-block quantum code}, booktitle={The Error Correction Zoo}, year={2023}, editor={Albert, Victor V. and Faist, Philippe}, url={} }
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“Two-block quantum code”, The Error Correction Zoo (V. V. Albert & P. Faist, eds.), 2023.