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TT: Fachverband Tiefe Temperaturen

TT 35: Postersession Transport: Nanoelectronics, Quantum Coherence and Quantum Information, Fluctuations and Noise

TT 35.29: Poster

Mittwoch, 25. März 2009, 14:00–18:00, P1A

Microwave Spectroscopy on Superconducting Flux Qubits — •Thomas Niemczyk¹, Lars Eggenstein^1,2, Frank Deppe^1,2, Elisabeth Hoffmann^1,2, Edwin Menzel¹, Matteo Mariantoni^1,2, Achim Marx¹, and Rudolf Gross^1,2 — ¹Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching, Germany — ²Physik-Department E23, Technische Universität München, Garching, Germany

There is promising progress in the realization of solid-state based quantum information processing (QIP) systems. Up to now, there is a number of different realizations of qubits, the building blocks for future quantum computers. Among these, superconducting (SC) qubits are very promising candidates. Furthermore, coupling SC qubits to high quality factor SC cavities opens the fascinating field of circuit quantum electrodynamics (cQED) where matter-light interaction can be studied on a fundamental level. We have fabricated SC flux-qubits which consist of an Al loop interrupted by 3 nm-sized Al/AlO_x/Al Josephson junctions. For readout, the qubit is inductively coupled to a dc-SQUID which detects the small flux signal (10⁻³ Φ₀) induced by the circulating currents in the qubit loop. The energy gap Δ between the ground state and the first excited state of the flux-qubits has been determined by µ-wave spectroscopy at 30 mK. We reproducibly could fabricate flux qubits with Δ values ranging between 3 and 5 GHz.
This work is supported by the DFG through SFB 631 and the Excellence Cluster ’Nanosystems Initiative Munich (NIM)’