caa a22 4500 467885001 CHVBK 20180406152731.0 cr unu---uuuuu 170328e20060701xx s 000 0 eng 10.1007/s10948-006-0168-5 doi (NATIONALLICENCE)springer-10.1007/s10948-006-0168-5 Macroscopic Quantum Phenomena in High Critical Temperature Superconducting Josephson Junctions [Elektronische Daten] [Tord Claeson, Floriana Lombardi, Thilo Bauch, Tobias Lindström, Per Delsing, Antonio Barone, Francesco Tafuri, Giacomo Rotoli] YBa2Cu3O7−δ grain boundary bi-epitaxial Josepshon junctions (JJs) allow a very clear demonstration of Josephson current variation with the misorientation angle, consistent with the d-wave symmetry of the superconducting order parameter in cuprate, high temperature superconductors. Our bi-epitaxial junctions show a strong suppression of the first harmonic, I 1 sin ø, of the current phase relation when tunneling from a lobe into a node of the superconducting gap function. In these configurations, the contribution of the second harmonic, I 2 sin 2ø, becomes of the same magnitude as the first one, giving rise to a characteristic two-well Josephson potential as a function of phase ø instead of the usual single well. This characteristic intrinsic property has suggested proposals of a new class of qu-bit named "quiet” because of the existence a spontaneously degenerate fundamental state without the need of applying an external field. Our experiments probe the macroscopic quantum properties in a d-wave Josephson junction by measuring macroscopic quantum tunneling and energy level quantization. The switching current out of the zero voltage state is measured as a function of temperature down to 20 mK. The temperature variation of the width of an ensemble of switching events goes over from one, which is characteristic of a thermal activation of phase fluctuations to a temperature independent width which is a token of quantum tunneling of the phase. The transition regime is affected by the two-well potential in a 45∘ misorientation junction as the second harmonic term gives rise to additional thermal transitions. The difference between quantized energy levels in the harmonic potential was determined by microwave spectroscopy. From the broadening of energy levels, it was possible to extract a Q-value of about 40 for the phase oscillations. The relatively high Q indicates quantum coherence over a sizeable time in d-wave junctions and gives hopes for a realization of a "quiet” high-T c qu-bit. The contributions of V. L. Ginzburg to several different fields of physics are impressive and long standing. In superconductivity the Ginzburg-Landau theory, for instance, still represents a very powerful approach to model a huge number of different physical systems. High Temperature Superconductors (HTS) have strongly influenced research of the last 20 years and their d-wave order parameter symmetry represents one of the most intriguing features from both the fundamental point of view and some types of innovative long-term applications. Springer Science + Business Media, Inc., 2006 Claeson Tord Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut Lombardi Floriana Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut Bauch Thilo Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut Lindström Tobias Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut Delsing Per Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut Barone Antonio INFM-Dipartimento di Fisica, Universita' di Napoli "Federico II,”, Napoli, Italy aut Tafuri Francesco INFM-Dipartimento Ingegneria dell'Informazione, Seconda Universita di Napoli, Aversa (CE), Italy aut Rotoli Giacomo Dipartimento di Ingegneria Meccanica, Energetica e Gestionale, Universita of L'Aquila, Localita Monteluco, L'Aquila, Italy aut Journal of Superconductivity and Novel Magnetism Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 19/3-5(2006-07-01), 341-347 1557-1939 19:3-5<341 2006 19 10948 https://doi.org/10.1007/s10948-006-0168-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10948-006-0168-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Claeson Tord Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut NATIONALLICENCE 700 1- Lombardi Floriana Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut NATIONALLICENCE 700 1- Bauch Thilo Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut NATIONALLICENCE 700 1- Lindström Tobias Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut NATIONALLICENCE 700 1- Delsing Per Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96, Göteborg, Sweden aut NATIONALLICENCE 700 1- Barone Antonio INFM-Dipartimento di Fisica, Universita' di Napoli "Federico II,”, Napoli, Italy aut NATIONALLICENCE 700 1- Tafuri Francesco INFM-Dipartimento Ingegneria dell'Informazione, Seconda Universita di Napoli, Aversa (CE), Italy aut NATIONALLICENCE 700 1- Rotoli Giacomo Dipartimento di Ingegneria Meccanica, Energetica e Gestionale, Universita of L'Aquila, Localita Monteluco, L'Aquila, Italy aut NATIONALLICENCE 773 0- Journal of Superconductivity and Novel Magnetism Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 19/3-5(2006-07-01), 341-347 1557-1939 19:3-5<341 2006 19 10948 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer