Less than two months remain before the APS March Meeting, which in terms of blogging means more short posts at odd hours, when I’m not in the lab trying to gather lots of last-minute data. Here’s the abstract for my talk:
Abstract: K40.00012 : Variable Coupling of Two Flux Qubits
5:06 PM–5:18 PM
T. Hime, P.A. Reichardt, B.L.T. Plourde, T.L. Robertson, C.-E. Wu, A.V. Ustinov, John Clarke
We report observations of variable coupling of two flux qubits. The qubits are coupled inductively to each other and to a readout Superconducting QUantum Interference Device (SQUID). By applying microwave radiation to the device, we observed resonant absorption in each of the qubits when the level splitting in the qubit matched the energy of the microwave photons. Using the two on-chip flux bias lines we adjusted the bias of each qubit so that the energy levels of the two qubits were equal; we then observed a splitting of the resulting absorption peak characteristic of coupling between the qubits. We varied the coupling between the qubits by changing the current bias in the SQUID in the zero voltage state, thereby changing its dynamic inductance and thus modifying the effective mutual inductance between the qubits. We compare the resulting changes in splitting with our predictions. This controllable coupling should be extendable to many qubits.
I’ll do a post explaining this in more detail around the time of my talk; some of this work is still, uh, “in progress”. (In fact we have performed all the experiments mentioned in the abstract, but we are working on collecting more/better data.) The talk immediately before mine covers some other results from these experiments.