Method for performing quantum error correction

A method of quantum error correction, comprising:

• receiving a parity check matrix H of a classical code, the parity check matrix H having p rows and n columns, n and p being positive integers;
• determining if a weight wr of a row r of the p rows is above a target weight threshold x;
• when the weight wr is above the target weight threshold x, reducing the weight wr by:
• replacing the row r with a matrix M having m rows, m being a positive integer, the matrix M comprising of a first sub-matrix and a second sub-matrix, wherein:
• the first sub-matrix comprises n columns, an i-th column of the first sub-matrix having a weight of 1 when an i-th element of the row r is 1, i being a positive integer, and the i-th column of the first sub-matrix having a weight of 0 when the i-th element of the row r is 0;
• the second sub-matrix comprises (m−1) columns, each column of the (m−1) columns of the second sub-matrix having a non-zero even-numbered weight and each row of the m rows of the second sub-matrix having a weight of less than or equal to (x−w1), w1 being equal to the weight of a corresponding row of the first sub-matrix;
• and
• appending (m−1) zeros to the end of each row of H that is not row r;
• and
• performing quantum error correction based on the parity check matrix after the reducing.