Invited) Hybrid quantum devices based on Josephson junctions

Kaveh Delfanazari

Kaveh Delfanazari

We experimentally demonstrate an on-chip hybrid S-Sm circuit consisting of eight Nb-In0.75Ga0.25As quantum wells-Nb ballistic Josephson junctions.

Rosario Fazio, Yuriy Makhlin, Gerd Schön

Kaveh Delfanazari, Pengfei Ma, Ian A. Farrer +4 more

...we introduced an integrated circuit consisting of arrays of planar Josephson junctions based on two-dimensional electron gas (2DEG) in In0.75Ga0.25As heterostructure. The methods that are used for ballistic 2D Josephson junction and hybrid quantum integrated circuit fabrication will be demonstrated. Furthermore, the temperature and magnetic field dependencies of the phase coherent quantum transport in 2D Josephson junctions, the induced superconducting properties into 2DEG, and the subharmonic energy gap structures (SGS) due to Andreev reflections at the S-Sm interfaces will be discussed. Reference: [1] K. Delfanazari, et al, Adv. Mater. 29, 1701836 (2017). [2] K. Delfanazari, et al, J. Magn. Magn. Mater. 459, 282-284 (2018). [3] K. Delfanazari, et al, IEEE Trans. Appl. Supercond. 28, 1100304 (2018).

D. Z. Haxell, Marco Coraiola, Manuel Hinderling +9 more

High Resolution Image Download MS PowerPoint Slide We perform switching current measurements of planar Josephson junctions (JJs) coupled by a common superconducting electrode with independent control over the two superconducting phase differences. We observe an anomalous phase shift in the current–phase relation of a JJ as a function of gate voltage or phase difference in the second JJ. This demonstrates the nonlocal Josephson effect, and the implementation of a φ 0 -junction which is tunable both electrostatically and magnetically. The anomalous phase shift is larger for shorter distances between the JJs and vanishes for distances much longer than the superconducting coherence length. Results are consistent with the hybridization of Andreev bound states, leading to the formation of an Andreev molecule. Our devices constitute a realization of a tunable superconducting phase source and could enable new coupling schemes for hybrid quantum devices.

Yossi Paltiel