Event Date and Time:

Mon, 2017-05-01 11:00 - 12:30
Local Contact:

Leanne Ebbs

Superconducting artificial atoms are created by connecting Josephson junctions, which are nonlinear, non-dissipative elements, to simple electrical circuits. Individual artificial atoms can be coupled using this same toolbox of inductors, capacitors, and Josephson junctions to build novel quantum materials. In this talk, I will discuss prospects for using the fluxonium artificial atom as a building block for topological materials. Topological phases of matter have excitations with exotic quantum statistics and have been proposed as a platform for robust quantum computation. Building a topological material from the bottom-up,
however, requires individual components with degenerate ground states and strong coupling between these components.
I will describe two circuits based on the fluxonium artificial atom that meet these requirements. The first circuit is an artificial molecule composed of two strongly-coupled fluxonium artificial atoms, which realizes a Hamiltonian with a dominant sigma_z sigma_z-type interaction between the individual atoms [1]. We find excellent agreement between the measured spectroscopy of the circuit and the theoretically-predicted level transitions, which highlights the suitability
of superconducting circuits for implementing tailored quantum systems. Instead of the cos 'energy term characteristic of a Josephson junction, the second circuit realizes an unconventional cos 2' energy term, which results in a nearly-degenerate ground-excited state manifold.
Taken together, these circuits fulfill the requirements for the building blocks of topological phases and we can thus start to realize topological materials using superconducting circuits.
[1] A. Kou, et al., arxiv:1610.01094 (2016).