Heterogeneous Quantum Error-Correcting Codes

We introduce quantum error-correcting codes (QECC) composed of qubits with distinct error channels. QECCs tailored to device noise have been extensively studied, however typically a single error channel is assumed for every qubit in the code. We explore this question for 2D and 3D topological codes in the code capacity limit and use maximum-likelihood decoding with approximate tensor network contraction to decode the errors. We demonstrate that fixing the location of qubits with different physical error channels leads to significantly higher error threshold and qubit overhead reduction.