Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 25: FV-internes Symposium ”Superconducting Qubits and π-junctions”
TT 25.4: Hauptvortrag
Donnerstag, 11. März 2004, 11:15–11:45, H20
Superconducting Structures for Quantum Computing — •Gianni Blatter1, Vadim Geshkenbein1, Mikhail Feigelman2, and Lev Ioffe3 — 1Theoretische Physik, ETH-Hönggerberg, CH-8093 Zürich — 2Landau Institute, RAS, Moskow, Russia — 3Department of Physics and Astronomy, Rutgers University, Piscataway, USA
In a quantum computer the information is stored in arrays of quantum two-level systems or ‘qubits’. Execution of a quantum algorithm involves quantum gates, unitary operations rotating individual qubits and entangling them pairwise. Superconducting solid-state qubits are promising candidates for the hardware implementation of scalable quantum information processors; quantum fluctuations are introduced through samll-capacitance Josephson junctions and the frustrating drive is introduced through a gate potential (charge-qubit) or a magnetic flux (phase- or flux qubit). Recent experiments have achieved a breakthrough with quality factors of the order of 104. Upscaling to a real quantum computer will require further improvements in noise reduction, manipulation, fault tolerance, and simplifications in design/fabrication. Superconductors with d-wave symmetry bear a number of benefits, such as the possibility to construct π- or double-periodic 2φ-junctions providing a quiet driving force and allowing for manipulation through switches. Further geometric frustration can be used to enhance quantum fluctuations in a new qubit design with tetrahedral symmetry, reducing charge noise and the demands on the fabrication of ultra-small junctions.