Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 103: Transport: Poster Session
TT 103.26: Poster
Donnerstag, 19. März 2015, 15:00–18:00, Poster B
Transmon qubits coupled to lumped element LC-readout-resonators — •Joel Cramer1, Peter Fehlner1, Jochen Braumüller1, Steffen Schlör1, Lucas Radtke1, Hannes Rotzinger1, Martin Weides2,1, and Alexey V. Ustinov3,1 — 1Physikalisches Institut, KIT, Wolfgang-Gaede-Straße 1, 76131 Karlsruhe, Germany — 2Institut für Physik, JGU, Staudingerweg 7, 55128 Mainz, Germany — 3Russian Quantum Center, 100 Novaya St., Skolkovo, Moscow, 143025, Russia
Superconducting qubits are among the most promising approaches for unit cells of a quantum computer or simulator. In this work, we investigated capacitively shunted Cooper pair boxes, so-called transmon qubits, each of them coupled to a superconducting readout resonator. Significant detuning of resonator and qubit enables non-demolition readout of the qubit state. Transmon qubits offer simple design and, in principle, large coherence time. In this work quasi-lumped element LC-resonators have been employed,which allow a compact qubit-resonator design of about 400 × 600 µm2. In total one chip contains 12 qubit-resonator pairs, each linked to its own fast-flux bias line. To implement and test these circuits, we have chosen simple optical lithography of aluminum films deposited on sapphire substrates. This approach results in relatively large junction sizes and reduced lifetimes due to large number of parasitic two-levels states within the tunnel barrier. Time domain measurements of the fabricated system revealed T1 lifetime of about 0.5 µ s, long enough to explore quantum phenomena like multi-level dressing.