Efficient schemes for reducing imperfect collective decoherences
Won-Young Hwang, Hyukjae Lee, Doyeol Ahn, Sung Yeon Hwang · Physical Review A · 2000
We propose schemes that are efficient when each pair of qubits undergoes some imperfect collective decoherence with different baths. In the proposed scheme, each pair of qubits is first encoded in a decoherence-free subspace composed of two qubits. Leakage out of the encoding space generated by the imperfection is reduced by the quantum Zeno effect. Phase errors in the encoded bits generated by the imperfection are reduced by concatenation of the decoherence-free subspace with either a three-qubit quantum error correcting code that corrects only phase errors or a two-qubit quantum error detecting code that detects only phase errors connected with the quantum Zeno effect again.