Scheme for Reducing Decoherence in Quantum Computer Memory by Transformation to the Coherence-Preserving States

If quantum bits (qubits) couple to the Same environment, it has been found the qubits decohere coherently. An interesting result from this phenomenon is that, for a kind of input states, i. e., the coherence-preserving states, coherence of the qubits can be preserved perfectly in quantum memory. In this paper, we propose a feasible scheme to transform an arbitrary unknown input state to the corresponding coherence-preserving state. The transformed state undergoes no decoherence in the noisy memory and, after that, it can be transformed back into the original state with decoherence much reduced. This scheme involves the use of an analogy of the ideas of quantum teleportation.