Experimental Investigation of a Two-Qubit Decoherence-Free Subspace
Joseph B. Altepeter, Phillip G. Hadley, S. M. Wendelken, Andrew J. Berglund, Paul G. Kwiat · Physical Review Letters · 2004
We thoroughly explore the phenomenon of a decoherence-free subspace (DFS) for two-qubit systems. Specifically, we both collectively and noncollectively decohere entangled polarization-encoded two-qubit states using thick birefringent crystals. These results characterize the basis-dependent effect of decoherence on the four Bell states, the robustness of the DFS state against perturbations in the assumption of collective decoherence, and the existence of a DFS for each type of stable noncollective decoherence. Finally, we investigate the effects of collective and noncollective dissipation.