Zhou, ZhongyuanChu, Shih-IHan, Siyuan2014-12-042014-12-042004-09-23Zhou, Zhongyuan., Chu, Shih-I., Han, Siyuan. "Suppression of energy-relaxation-induced decoherence in Λ-type three-level SQUID flux qubits: A dark-state approach." Phys. Rev. B 70, 094513 – Published 23 September 2004. http://dx.doi.org/10.1103/PhysRevB.70.094513.https://hdl.handle.net/1808/16035This is the published version, also available here: http://dx.doi.org/10.1103/PhysRevB.70.094513.We report a theoretical investigation of decoherence induced by energy relaxation of the auxiliary level in the Λ-type three-level SQUID flux qubits. We show that the energy-relaxation-induced decoherence in this particular case is proportional to the average population of the auxiliary level and thus can be effectively suppressed by the use of a dark-state approach in which the auxiliary level is unpopulated. We demonstrate through bit-flip operation that the dark state can be realized by means of the stimulated Raman adiabatic passage (STIRAP). An extension of the dark-state scheme to create any superposition state is straightforward.Article10.1103/PhysRevB.70.094513openAccess