Jens Koch, Northwestern University
Abstract
Quantum coherence in superconducting circuits has been a fruitful playground for theorists and experimentalists seeking possible routes towards quantum computation, or teaching microwave photons new quantum optics tricks. While coherence times in such circuits have undergone a remarkable increase of 5 orders of magnitude over the last decade, a different property has remained largely stagnant: following the "simpler is better" mantra, circuits across all borders between phase, flux, and charge qubits, consistently employ less than a handful of circuit elements. A recent experiment with a new circuit composed of over 40 elements, dubbed "fluxonium", could be the kick-off for a paradigm change and make the world of superconducting circuits a lot bigger.
In this talk, I will discuss the obstacles and successes in achieving quantum coherence in superconducting circuits. I will showcase their applications in circuit QED, and present our work on developing theory for
circuits with many degrees of freedom.