Superconducting island

Whereas coherence can persist up to the nanosecond range for atomic and molecular systems exposed to dilute gaseous environments, the situation is radically different in liquids and solids. Interactions with neighbouring atoms, with phonons in crystalline materials and with conduction electrons in metals, shift the coherence times down by several orders of magnitude, and local quantum superpositions are usually not observable. Intermediate cases are the electronic states used as qubits in the form of superconducting islands introduced by Y. Nakamura et al. [4]. The latest reports [5] show coherence times up to 10 s for these objects, which would allow time for operations of a quantum computer. The decoherence mechanisms in such circuits have been discussed theoretically by Burkhard et al. [6],... 

A number of other questions not yet accessible experimentally, like destruction of the quantum-mechanical coherence in the moving island [9] and a possibility of superconducting phase coherence across the shuttle [10] is at the focus of theoretical research. 

Figure 27 QSD and Mathias plots for 175 high-Ti ferroelecfrics and antiferroelectrics. Pseudotemaries and quaternaries with > 500 K (set F3) are represented by sohd triangles the ternaries with > 500 K (set F ) are represented by a variety of symbols distinguishing different structure types, as shown in the legend (all scales are expanded by a factor of 2 relative to Figure 26). The outline for the island C from Figure 26 is shown as a dashed line to facilitate comparison of ferroelectric and superconducting domains. (Ref. 33. Reproduced by...

Raman investigations show another transition or cross-over at the Neel temperature (x = 6.22). Deconvolution of the apex-phonon width shows the coexistence of four phases in the nonstoichiometric range of 123. It is possible that physical phase separation starts at x = 6.22 with the formation of hole-doped islands in an AF matrix (sect. 3.3.2), the percolation to the superconducting phase taking place at x w 6.40. 

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