Abstract: In distributed computing, a byzantine fault is a condition where some components of a multi-component system fail, but it is unclear which components fail and which ones function properly. A deterministic protocol to reliably broadcast information in such a setting was proposed by Pease et al. [1]. More recent ideas built upon distributed entangled quantum states [2,3,4] are worth considering as they offer a reduced communication cost. In this talk, I will outline recent unpublished results of a Budapest collaboration among researchers of Nokia Bell Labs, BME and the Wigner Research Centre for Physics. I will introduce a family of quantum-aided weak broadcast protocols. I will show our results of a resource optimization procedure, illustrating the engineering aspects of future deployment of such protocols in practice. The protocols I'll discuss rely on a specific 4-qubit entangled resource state. Following earlier work demonstrating the suitability of noisy intermediate-scale quantum (NISQ) devices for the study of quantum networks [5], I will show how to prepare our resource state on publicly available IBM quantum-computer prototypes. Finally, I plan to discuss future research directions toward quantum-aided byzantine fault tolerance.

 

[1] M. Pease et al., J. ACM 27, 228 (1980).

[2] M. Fitzi, N. Gisin, U. Maurer, Phys. Rev. Lett. 87, 217901 (2001).

[3] A. Cabello, Phys. Rev. A 68, 012304 (2003).

[4] S. Gaertner et al., Phys. Rev. Lett. 100, 070504 (2008).

[5] P. Pathumsoot et al., Phys. Rev. A 101, 052301 (2020)

 

About the speaker: Andras Palyi is a theoretical physicist, working as an associate professor at the Department of Theoretical Physics, Budapest University of Technology and Economics. He obtained his PhD in condensed-matter theory at the Eotvos Lorand University in Budapest, and held a postdoc position at the University of Konstanz, in Germany, before moving back to Budapest in 2011. Since his PhD, Andras has been doing research at the interface of condensed-matter physics and quantum information, doing theory work toward the goal of practical, experimental quantum information processing.