AQP Seminar: Experimental benchmark of small quantum processors

Aalto Quantum Physics -seminaari (Nanotalo). Puhuja: Mr. Johannes Heinsoo (QCD group, Aalto-yliopisto)

The number of superconducting qubits tends to double during the study of a single PhD student, and companies including Google [1], IBM [2], Intel [3] and Rigetti [4] already claim to work on quantum processors sufficiently large to demonstrate quantum supremacy. These machines employ transmon type qubits with improved coherence and reliable gate performance. I will give a short introduction to the transmon qubits and experiments carried out to benchmark the performance of 2, 4 and 8 qubit devices in ETH Zürich. The benchmark experiments include a free-will-based Bell test [5], a full state tomography of 4-qubit maximally-entangled GHZ state, entanglement swapping, entanglement distillation and characterization of 8-qubit low-crosstalk frequency-multiplexed readout circuit [6]. The results of these benchmark experiments allow for the identification of specific challenges in designing and running multi-qubit experiment and, thus, provide essential information for building larger quantum devices in the near future. 

[1] https://ai.googleblog.com/2018/03/a-preview-of-bristlecone-googles-new.html
[2] https://rebootingcomputing.ieee.org/rebooting-computing-week/industrycomputingsummit
[3] https://newsroom.intel.com/news/intel-advances-quantum-neuromorphic-computing-research/#gs.Kjy0lp0A

[4] https://medium.com/rigetti/the-rigetti-128-qubit-chip-and-what-it-means-for-quantum-df757d1b71ea
[5] Challenging local realism with human choices, The BIG Bell Test Collaboration, Nature 557, 212–216 (2018), also in arXiv:1805.04431

[6] Rapid High-fidelity Multiplexed Readout of Superconducting Qubits, J. Heinsoo et al., Phys. Rev. Applied 10, 034040 (2018), also in arXiv:1801.07904