Demonstration of Superconducting Schrodinger¡¦s Cat in a Josephson Jjunction Siyuan Han Department of Physics and Astronomy University of Kansas It has been demonstrated recently that a Josephson junction (JJ), a superconducting electronic device, can be used to create a laboratory version of the famous Schrodinger cat [Y. Yu et al., Sicence 296, p889 (May 2002)]. I¡¦ll show that when sufficiently isolated from environments a current biased JJ biased is a very well characterized and controllable macroscopic quantum object and that Rabi oscillations can be utilized to create coherent superposition of macroscopic quantum states. For the first time, we have observed this macroscopic superposition state, i.e., Schrodinger¡¦s Cat state, in time domain as it oscillates coherently between the ¡§alive¡¨ and ¡§dead¡¨ state of the junction. The coherence time, estimated from the exponentially decaying amplitude of the oscillations, is about 5 s which is very promising for quantum computing using the ¡§phase¡¨ qubits (JJs) and the ¡§flux¡¨ qubits (SQUIDs).