Simplified Josephson-junction fabrication process for reproducibly high-performance superconducting qubits
Artikel i vetenskaplig tidskrift, 2021

We introduce a simplified fabrication technique for Josephson junctions and demonstrate superconducting Xmon qubits with T1 relaxation times averaging above 50 μs (Q > 1.5 × 1 0 6). Current shadow-evaporation techniques for aluminum-based Josephson junctions require a separate lithography step to deposit a patch that makes a galvanic, superconducting connection between the junction electrodes and the circuit wiring layer. The patch connection eliminates parasitic junctions, which otherwise contribute significantly to dielectric loss. In our patch-integrated cross-type junction technique, we use one lithography step and one vacuum cycle to evaporate both the junction electrodes and the patch. This eliminates a key bottleneck in manufacturing superconducting qubits by reducing the fabrication time and cost. In a study of more than 3600 junctions, we show an average resistance variation of 3.7% on a wafer that contains forty 0.5 × 0.5-cm2 chips, with junction areas ranging between 0.01 and 0.16 μm2. The average on-chip spread in resistance is 2.7%, with 20 chips varying between 1.4% and 2%. For the junction sizes used for transmon qubits, we deduce a wafer-level transition-frequency variation of 1.7%-2.5%. We show that 60%-70% of this variation is attributed to junction-area fluctuations, while the rest is caused by tunnel-junction inhomogeneity. Such high frequency predictability is a requirement for scaling-up the number of qubits in a quantum computer.

qubits

Superconducting Resonators

Josephson Junctions

Författare

Amr Osman

Chalmers, Mikroteknologi och nanovetenskap (MC2), Kvantteknologi

James Simon

Chalmers, Mikroteknologi och nanovetenskap (MC2), Kvantteknologi

Andreas Bengtsson

Chalmers, Mikroteknologi och nanovetenskap (MC2), Kvantteknologi

Sandoko Kosen

Chalmers, Mikroteknologi och nanovetenskap (MC2), Kvantteknologi

Philip Krantz

Administration MC2

Daniel Perez Lozano

Chalmers, Mikroteknologi och nanovetenskap (MC2), Kvantteknologi

Marco Scigliuzzo

Chalmers, Mikroteknologi och nanovetenskap (MC2), Kvantteknologi

Per Delsing

Chalmers, Mikroteknologi och nanovetenskap (MC2), Kvantteknologi

Jonas Bylander

Chalmers, Mikroteknologi och nanovetenskap (MC2), Kvantteknologi

Anita Fadavi Roudsari

Chalmers, Mikroteknologi och nanovetenskap (MC2), Kvantteknologi

Applied Physics Letters

0003-6951 (ISSN) 1077-3118 (eISSN)

Vol. 118 6 064002

Ämneskategorier

Atom- och molekylfysik och optik

Annan fysik

Den kondenserade materiens fysik

DOI

10.1063/5.0037093

Mer information

Senast uppdaterat

2021-03-18