QuantumClifford.jl #511
LPCode built non-commuting stabilizers whenever the group was non-abelian, because only the left regular representation was used. I switched one factor to the right regular representation, following Panteleev and Kalachev, which restores CSS orthogonality for any finite group.
$$\lambda(a)\rho(b)=\rho(b)\lambda(a)\Rightarrow H_XH_Z^{\top}=0$$
“This is great, a really solid improvement.” (Stefan Krastanov, review)
Oscar.jl #5075
Oscar's homology raised an error for chain complexes of modules over finite fields such as GF(2). I extended it upstream, then used Oscar chain complexes to build D-dimensional surface and toric codes in QuantumClifford.jl.
$$H_k=\ker\partial_k\,/\,\operatorname{im}\partial_{k+1}\quad\text{over }\mathbb{F}_2$$
Used in QuantumClifford.jl #534
QuantumClifford.jl #534
Generalized the 2D, 3D and 4D surface and toric codes to arbitrary D, built as tensor products of repetition-code chain complexes in Oscar. The boundary maps give both parity checks and metachecks.
$$\mathcal{C}=\mathcal{R}_L^{\otimes D},\qquad k=\dim H_q(\mathcal{C};\mathbb{F}_2)$$
QuantumClifford.jl #564
Multi-sector homological product codes from classical and quasi-cyclic codes, and the double homological product, built on the same Oscar homological algebra. I also wrote the Double Homological Product entry for the Error Correction Zoo.
$$\mathcal{C}_1\otimes\mathcal{C}_2\otimes\cdots\otimes\mathcal{C}_D$$
Also in the Error Correction Zoo
QuantumClifford.jl #476
A hypergraph-product-style family built from a structured classical LDPC code with parity-check matrix [C | M]. I also contributed it to the Error Correction Zoo.
$$[[\,n^2+m^2,\ k,\ d\,]],\quad H=[C\,|\,M]$$ $$k=(n-\operatorname{rk}H)^2+(m-\operatorname{rk}H^{\top})^2$$
Also in the Error Correction Zoo
QuantumClifford.jl #439
A solver-agnostic MILP formulation that certifies the distance of quantum LDPC codes. It is now the library's exact distance method, and I use it to certify code distances in my own work.
$$d_Z=\min\{\,|x| : H_Xx=0,\ \ell\cdot x=1\,\}$$
QuantumClifford.jl #427
In-place Pauli measurement for generalized stabilizer states, following Yoder's algorithm, so circuits with T gates can be simulated with measurements, without the state's inverse sparsity Λ growing.
$$\Lambda(\chi')\le\Lambda(\chi)$$
QuantumClifford.jl #606
The reference implementation of MM codes: Koszul matrices with each variable replaced by its circulant, and a metacheck interface so decoders can use the check redundancy.
$$\partial_k=\mathrm{Koszul}_k(F_1,\dots,F_t)\big|_{x_i\mapsto C_{\ell_i}}$$