[NOTE: This section is still under construction]

We read the intros of our main references [1-6] to gather how we best answer:

• How do they introduce the current and prospective applications of the field as well as its problems?
• Explain the DiVincenzo criteria of what makes a system a qubit:

DiVincenzo Criteria, illustration adapted from [6]

• Start off with a global perspective: What are the relevant qubit architectures in 2026?

  We have engineered physical quantum two-level systems as the 1/0 of quantum computers (?!) in a variety of platforms ranging from photonics and atomic systems to nano-mechanical structures and superconducting circuits. [2]

• Introduce different types of qubit modalities/architectures

  Link in a future Appendix.

• How did we get here, a brief historical introduction. Since the beginning of circuit QED: pronounced interplay between science and engineering in the superconducting circuit technology

• What is the latest status of superconducting qubits in particular?

  Photons are suited for transmitting quantum information, while atoms can serve as long-lived quantum memories. In this regard, superconducting circuits, working by using photons to create an “artificial atom”, have gained a lot of attention for quantum computation owing to the strong light-matter interaction achievable in these circuits. [Naghiloo]

  • Active research area ranging from fundamental studies to practical applications

• What are key problems in the field of superconducting qubits?

  • Scalability: the components for SC computing are large and it takes a lot of resources to run a DR

    [7, **tbc …]

  • The physical system is hard to engineer: feedline, resonator, and qubit. Cross, claw, terminology. Ground plane. Capacitive coupling.

  • The analytic equations themselves are inconsistent: There’s a set of analytical equations familiar to people, but it has problems.

    There have been attempts to unite the quantum parameters, namely the coupling $g$ and the dispersive shift $\chi$ with the classical L and C; this is problematic. You can do that though, as an estimate, and we’ll learn how. We don’t measure capacitances and inductances directly, so we’ll talk about that too.

  • On the simulation side: here it’s a similar story, when doing numerical simulations, you get out capacitances and inductances and then you try to plug those in to these problematic analytical equations to get g, and so on.

  • Interactions with the qubit need to be improved ( Longer coherence times, higher fidelity, higher fault tolerance)

• Explain the content and flow of the Chapters

Main references for us:

[1] S. Ganjam, Improving the Coherence of Superconducting Quantum Circuits through Loss Characterization and Design Optimization

[2] M. Naghiloo, Introduction to Experimental Quantum Measurement with Superconducting Qubits, arXiv:1904.09291

[3] S. Shanto, A. Kuo, C. Miyamoto, H. Zhang, V. Maurya, E. Vlachos, M. Hecht, C. W. Shum, and E. Levenson-Falk, Quantum 8, 1465 (2024)