Movassagh-Ouyang Hamiltonian code[1] 


This is a family of codes derived via an algorithm that takes as input any binary classical code and outputs a quantum code (note that this framework can be extended to \(q\)-ary codes). The algorithm is probabalistic but succeeds almost surely if the classical code is random. An explicit code construction does exist for linear distance codes encoding one logical qubit. For finite rate codes, there is no rigorous proof that the construction algorithm succeeds, and approximate constructions are described instead.

This family strictly generalizes CSS codes (because CSS codes come only from linear or self orthogonal classical codes). These codes can be shown to be realized as a subspace of the ground space of a (geometrically) local Hamiltonian.


Let \(C \subset \{0,1,\dots,q-1\}^n\) be a classical code with distance \(d_x\). Let \(d_z\) satisfy \(q^n > 2 V_q(d_z-1) -1\), where \(V_q(r)\) is the volume of the \(q\)-ary Hamming ball of radius \(r\). Then the algorithm produces a quantum code with distance \(d = \text{min}(d_x,d_z)\). Asymptotically, the distance scales linearly with \(n\).


The rate depends on the classical code, but distance can scale linearly with \(n\).



  • Qubit CSS code — Movassagh-Ouyang codes stem from a prescription that converts an arbitrary classical code into a quantum code.



R. Movassagh and Y. Ouyang, “Constructing quantum codes from any classical code and their embedding in ground space of local Hamiltonians”, (2020) arXiv:2012.01453
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Zoo Code ID: movassagh_ouyang

Cite as:
“Movassagh-Ouyang Hamiltonian code”, The Error Correction Zoo (V. V. Albert & P. Faist, eds.), 2021.
  title={Movassagh-Ouyang Hamiltonian code},
  booktitle={The Error Correction Zoo},
  editor={Albert, Victor V. and Faist, Philippe},
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Cite as:

“Movassagh-Ouyang Hamiltonian code”, The Error Correction Zoo (V. V. Albert & P. Faist, eds.), 2021.