Group Seminar via Zoom: Classical and quantum optimization of superconducting quantum processors
Tim Menke, MIT
Group Seminar via video conference (Zoom)
Tuesday, July 13th, 11.00 am (MEZ)
Dealing with the unique situation of partial lock downs worldwide and home office solutions at our Institute due to the current spreading of the Covid 19 virus, we are now holding our group seminars and journal clubs via video conference.This procedure enables us to continue our research, enhance discussions and exchange important information.
Superconducting circuits have emerged as a promising platform to build quantum processors. The challenge of designing a circuit is to compromise between realizing a set of performance metrics and reducing circuit complexity and noise sensitivity. At the same time, one needs to explore a large design space, and computational approaches often yield long simulation times. In this talk, I will present two approaches to alleviate these challenges. First, I will show how we automate the circuit design task using the software SCILLA . Our software performs a parallelized, closed-loop optimization to find superconducting circuit diagrams that match predefined properties. In particular, we employ it to design a 4-local coupler for superconducting flux qubits. I will show experimental results that verify the operation principle of the coupler circuit, which validates the automated design approach. We also find that the circuit does not adversely affect the lifetime of a connected flux qubit and is suitable as a scalable coupling module. In the second part of the talk, I will describe an approach to simulate superconducting circuits on a quantum computer . We demonstrate how the energy spectra of superconducting transmon qubits can be obtained by variational hybrid quantum-classical algorithms that are well-suited for near-term noisy quantum computers. In addition, single- and two-qubit gate simulations are performed via Suzuki-Trotter decomposition. We thereby provide a path towards the simulation of quantum hardware that is too large or complex to simulate on a classical computer.
 Tim Menke et al., Automated discovery of superconducting circuits and its application to 4-local coupler design, npj Quant. Inf. 7 (1), 49 (2021).
 Thi Ha Kyaw & Tim Menke et al., Quantum computer-aided design: digital quantum simulation of quantum processors, arXiv:2006.03070 (2020).
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