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How much entanglement is needed for quantum error correction?

Quantum Physics 2025-06-16 v2 Mathematical Physics math.MP

Abstract

It is commonly believed that logical states of quantum error-correcting codes have to be highly entangled such that codes capable of correcting more errors require more entanglement to encode a qubit. Here, we show that the validity of this belief depends on the specific code and the choice of entanglement measure. To this end, we characterize a tradeoff between the code distance dd quantifying the number of correctable errors, and the geometric entanglement measure of logical states quantifying their maximal overlap with product states or more general ``topologically trivial" states. The maximum overlap is shown to be exponentially small in dd for three families of codes: (1) low-density parity check codes with commuting check operators, (2) stabilizer codes, and (3) codes with a constant encoding rate. Equivalently, the geometric entanglement of any logical state of these codes grows at least linearly with dd. On the opposite side, we also show that this distance-entanglement tradeoff does not hold in general. For any constant dd and kk (number of logical qubits), we show there exists a family of codes such that the geometric entanglement of some logical states approaches zero in the limit of large code length.

Keywords

Cite

@article{arxiv.2405.01332,
  title  = {How much entanglement is needed for quantum error correction?},
  author = {Sergey Bravyi and Dongjin Lee and Zhi Li and Beni Yoshida},
  journal= {arXiv preprint arXiv:2405.01332},
  year   = {2025}
}
R2 v1 2026-06-28T16:14:07.284Z