High-kinetic inductance NbN films for high-quality compact superconducting resonators

  1. Simone Frasca,
  2. Ivo Nikolaev Arabadzhiev,
  3. Sebastien Yves Bros de Puechredon,
  4. Fabian Oppliger,
  5. Vincent Jouanny,
  6. Roberto Musio,
  7. Marco Scigliuzzo,
  8. Fabrizio Minganti,
  9. Pasquale Scarlino,
  10. and Edoardo Charbon
Niobium nitride (NbN) is a particularly promising material for quantum technology applications, as entails the degree of reproducibility necessary for large-scale of superconducting
circuits. We demonstrate that resonators based on NbN thin films present a one-photon internal quality factor above 105 maintaining a high impedance (larger than 2kΩ), with a footprint of approximately 50×100 μm2 and a self-Kerr nonlinearity of few tenths of Hz. These quality factors, mostly limited by losses induced by the coupling to two-level systems, have been maintained for kinetic inductances ranging from tenths to hundreds of pH/square. We also demonstrate minimal variations in the performance of the resonators during multiple cooldowns over more than nine months. Our work proves the versatility of niobium nitride high-kinetic inductance resonators, opening perspectives towards the fabrication of compact, high-impedance and high-quality multimode circuits, with sizable interactions.

Characterization and Analysis of On-Chip Microwave Passive Components at Cryogenic Temperatures

  1. Bishnu Patra,
  2. Mohammadreza Mehrpoo,
  3. Andrea Ruffino,
  4. Fabio Sebastiano,
  5. Edoardo Charbon,
  6. and Masoud Babaie
This paper presents the characterization of microwave passive components, including metal-oxide-metal (MoM) capacitors, transformers, and resonators, at deep cryogenic temperature (4.2
K). The variations in capacitance, inductance and quality factor are explained in relation to the temperature dependence of the physical parameters and the resulting insights on modeling of passives at cryogenic temperatures are provided. Both characterization and modeling, reported for the first time down to 4.2 K, are essential in designing cryogenic CMOS radio-frequency integrated circuits, a promising candidate to build the electronic interface for scalable quantum computers.

A Reconfigurable Cryogenic Platform for the Classical Control of Scalable Quantum Computers

  1. Harald Homulle,
  2. Stefan Visser,
  3. Bishnu Patra,
  4. Giorgio Ferrari,
  5. Enrico Prati,
  6. Fabio Sebastiano,
  7. and Edoardo Charbon
Recent advances in solid-state qubit technology are paving the way to fault-tolerant quantum computing systems. However, qubit technology is limited by qubit coherence time and by the
complexity of coupling the quantum system with a classical electronic infrastructure. We propose an infrastructure, enabling to read and control qubits, that is implemented on a field-programmable gate array (FPGA). The FPGA platform supports functionality required by several qubit technologies and can operate physically close to the qubits over a temperature range from 4K to 300K. Extensive characterization of the platform over this temperature range revealed all major components (such as LUTs, MMCM, PLL, BRAM, IDELAY2) operate correctly and the logic speed is very stable. The stability is finally concretized by operating an integrated ADC with relatively stable performance over temperature.