Macroscopic Quantum Coherence and Quantum Computing

This volume is an outgrowth of the Second International Workshop on Macroscopic Quantum Coherence and Computing held in Napoli, Italy, in June 2000. This workshop gathered a number of experts from the major Universities and Research Institutions of several countries. The choice of the location, which recognizes the role and the traditions of Naples in this field, guaranteed the participants a stimulating atmosphere. The aim of the workshop has been to report on the recent theoretical and experimental results on the macroscopic quantum coherence of macroscopic systems. Particular attention was devoted to Josephson devices. The correlation with other atomic and molecular systems, exhibiting a macroscopic quantum behaviour, was also discussed. The seminars provided both historical overview and recent theoretical ground on the topic, as well as information on new experimental results relative to the quantum computing area. The first workshop on this topic, held in Napoli in 1998, has been ennobled by important reports on observations of Macroscopic Quantum Coherence in mesoscopic systems. The current workshop proposed, among many stimulating results, the first observations of Macroscopic Quantum Coherence between macroscopically distinct fluxoid states in rf SQUIDs, 20 years after the Leggett's proposal to experimentally test the quantum behavior of macroscopic systems. Reports on observations of quantum behaviour in molecular and magnetic systems, small Josephson devices, quantum dots have also been particularly stimulating in view of the realization of several possible q-bits. Front Matter....Pages i-xi Macroscopic Quantum Coherence and Decoherence in Squids....Pages 1-6 Macroscopic Quantum Coherence in an Rf-SQUID....Pages 7-16 Quantum-State Interference in a Cooper-Pair Box....Pages 17-24 Macroscopic Quantum Superposition in a Three-Josephson-Junction Loop....Pages 25-34 Bose-Einstein Condensation with Attractive Interaction Fate of a False Vacuum....Pages 35-40 Macroscopic Quantum Phenomena in Atomic Bose-Einstein Condensates....Pages 41-50 Phase-Coherent Electronic Transport in a Multi-Wall Carbon Nanotube....Pages 51-60 Macroscopic Quantum Phenomena in Underdamped Josephson Junctions....Pages 61-71 Superconducting Devices to Test Macroscopic Quantum Coherence on the Flux States of a Rf SQUID....Pages 73-82 Biepitaxial YBa 2 Cu 3 O 7-x Grain Boundary Josephson Junctions: 0- and π- Rings for Fundamental Studies and Potential Circuit Implementation....Pages 83-100 The Superconducting Single Electron Transistor: in situ Variation of the Dissipation....Pages 101-110 Superconducting Electrometer for Measuring the Single Cooper Pair Box....Pages 111-125 Adiabatic Transport of Cooper Pairs in Arrays of Small Josephson Junctions....Pages 127-136 Entangled States in a Josephson Charge Qubit Coupled to a Superconducting Resonator....Pages 137-145 Cooper Pair Tunneling in Circuits with Substantial Dissipation: The Three-Junction R-Pump for Single Cooper Pairs....Pages 147-154 Nonlocality in Superconducting Microstructures....Pages 155-163 Characterisation of Cooper Pair Boxes for Quantum Bits....Pages 165-172 Noise Measurements of a Superconducting Single Electron Transistor (SSET) at T=0.3K....Pages 173-181 Quantum Coherence and Decoherence in Magnetic Nanostructures....Pages 183-193 MQT of Magnetic Particles....Pages 195-205 Abrupt Transition Between Thermally-Assisted and Pure Quantum Tunneling in Mn 12 ....Pages 207-214 Quantum Effects in the Dynamics of the Magnetization in Single Molecule Magnets....Pages 215-223 Quantum Coherence and Very Low Temperature Magnetic Experiments in Mesoscopic Magnets....Pages 225-234 Quantum Gates and Networks with Cavity QED Systems....Pages 235-244 Dual Josephson Phenomena: Interaction of Vortices with Non-Classical Microwaves....Pages 245-252 Quantum Computation: Theory, Practice, and Future Prospects....Pages 253-260 Reading-Out a Quantum State: An Analysis of the Quantum Measurement Process....Pages 261-270 Adiabatic Inversion in the Squid, Macroscopic Coherence and Decoherence....Pages 271-283 Quantum Computing with Separable States?....Pages 285-292 Spintronics and Quantum Computing with Quantum Dots....Pages 293-306 Double Quantum Dot Coupled to Two Superconductors: Transport and Spin Entanglement....Pages 307-315 Transport Through Artificial Kondo Impurities....Pages 317-324 Compensation of the Spin of a Quantum dot at Coulomb Blockade....Pages 325-340 Multi-particle entanglement in quantum computers....Pages 341-350 Stabilization of Quantum Information: A Unified Dynamical-Algebraic Approach....Pages 351-357 1/ F Noise During Manipulation of Josephson Charge Qubits....Pages 359-366 Non-Markovian dynamics in continuous-wave atom lasers....Pages 367-380 Time-Correlated Macroscopic Quantum Tunneling of Solitons in Density Waves and Long Josephson Junctions....Pages 381-388 The Non-Perturbative Quantum Behaviour of a Squid Ring in a Strong Electromagnetic Field....Pages 389-398 Noise properties of the SET transistor in the co-tunneling regime....Pages 399-407 Charge Fluctuations and Dephasing in Coulomb Coupled Conductors....Pages 409-418 The Measurement of Photon Number States Using Cavity QED....Pages 419-426 Abrupt Magnetoresistance Jumps in Ni-Wire Systems and Coulomb Blockade Under Elastic Environment in Single Junction/Carbon Nanotube System....Pages 427-442 Spontaneous generation of flux in a Josephson junction loop....Pages 443-448 Soliton Quantum Bit....Pages 449-457 Back Matter....Pages 459-460 This volume gives the historical and recent theoretical ground of the topic as well as detailed information on experimental results on the quantum behavior of macroscopic systems, together with some considerations on perspectives in the quantum computing area. Particular attention is given to the coherence effects in Josephson systems. The correlation with other atomic and molecular systems, exhibiting a macroscopic quantum coherence behavior is also discussed. Such proposals are considered for implementation of various schemes for coherent information processing and quantum computation.