[RpL 1281] IRQ'2020: Lecture by Ioan Pop 'Introduction to high impedance quantum circuits'

[Alexander Semenov]

Dear all,
Today, on Monday November 23, at 17.00 Moscow time (15.00 CET, 14.00 GMT), lecture 'Introduction to high impedance quantum circuits' will be given by Dr. Ioan Pop from Karlsruhe Institute of Technology. Please find the abstract in the bottom of this email.
Link to Zoom meeting: https://zoom.us/j/8976647786?pwd=SjBSTVNqRG1uaCsrYjJDVit5eTduUT09
(For those who plan to get certificate and want to be counted by as accurately: 1) please check that your Zoom nick allows to identify you unambiguously; 2) after entering, send a private message via the chat, with any text,  to the person named 'Registration').
Link to the site of the School with the Program:
https://irq2020.quant.physics.mpgu.edu/
Sincerely,
On behalf of Organisers of IRQ'2020,
Alexander Semenov
P. S. If you don't want to receive our emails, please respond to this one by an email containing word 'NO' in the body.
Ioan Pop
Introduction to high impedance quantum circuits
Superconducting quantum information processing machines are predominantly based on microwave circuits with relatively low characteristic impedance, about 100 Ohm, and small anharmonicity, which can limit their coherence and logic gate fidelity. I will discuss a promising alternative, namely circuits based on so-called superinductors, with characteristic impedances exceeding the resistance quantum R_Q = 6.4 kOhm. However, superinductors are not easy to come by. Previous implementations consisting of mesoscopic Josephson junction arrays can introduce unintended nonlinearity or parasitic resonant modes, degrading device coherence. I will present designs based on a particularly promising disordered superconducting material: granular aluminum (grAl) [1]. I will argue that grAl forms a compact effective junction array with high kinetic inductance and amenable nonlinearity [2,3], which can be in-situ integrated with standard aluminum circuit processing. I will also point out that quasiparticle poisoning can be a limiting factor [4] and should be addressed in future works.
[1] Grunhaupt, Spiecker et al. Nature Materials 18, 816-819 (2019)
[2] Maleeva et al. Nature Comm. 9, 3889 (2018)
[3] Winkel et al. PRX 10, 031032 (2020)
[4] Grunhaupt et al., Phys. Rev. Lett. 121, 117001 (2018)