Quantum Error Correction - General Codes

General Codes

In general, a quantum code for a quantum channel is a subspace, where is the state Hilbert space, such that there exists another quantum channel with

 (\mathcal{R} \circ \mathcal{E})(\rho) = \rho \quad \forall \rho = P_{\mathcal{C}}\rho P_{\mathcal{C}},

where is the orthogonal projection onto . Here is known as the correction operation.

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