In recent years many designs have been demonstrated for quantum bits (qubits) based on the Josephson effect in low critical temperature superconductors. The use of such technology appears to be a natural choice since superconductors offer both the scalability, typical of solid state technology, and the properties of a macroscopic quantum system. The results on such qubits to date, though in many respects quite impressive, still need improvements to achieve the level of performance required for quantum computation. The main issue when dealing with qubits is to reduce possible sources of decoherence that would be detrimental to its performances. A big effort has been made by many groups to understand the effect of materials and fabrication on decoherence times and to explore the potential of hybrid devices. The main aim of this proposal is to demonstrate the feasibility of a qubit of sufficient quality to form the building blocks of a quantum information technology partly based on Josephson effect in high Tc superconductors. The specific configurations we intend to explore may offer atomically flat barriers with advantages in terms of reduced noise and “quitness”, which may also benefit of intrinsic quantum protection of High Tc systems. The team will focus toward chip design and circuit implementation and filtering to improve the qubit isolation from external sources of noise and decoherence. A spectroscopic approach will be implemented to study the intrinsic effects of materials and fabrication process on the decoherence time.
Fields of science
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