It is well known that the time evolution of the quantum harmonic oscillator is identical to that of its classical counterpart. So it came as a surprise (at least to me) to find an unnoticed preprint by Tsirelson [1] claiming that one can base a certification of non-classicality on just observing that evolution in a smart way. In this talk, I shall explain Tsirelson's idea and review the follow-up works done in my group ([2-8]), finishing with the first experimental demonstration of this protocol [9].

[1] B. Tsirelson, arXiv: quant-ph/0611147

[2] L. H. Zaw et al., Phys. Rev. A 106, 032222 (2022)

[3] P. Jayachandran et al., Phys. Rev. Lett. 130, 160201 (2023)

[4] L. H. Zaw, V. S., Phys. Rev. A 108, 022211 (2023)

[5] N. Huynh-Vu et al., Phys. Rev. A 109, 042402 (2024)

[6] J. Chen et al., Phys. Rev. A 110, 062408 (2024)

[7] L. H. Zaw et al., Phys. Rev. Lett. 134, 190201 (2025)

[8] L. H. Zaw, V.S., npj Quantum Inf. 11, 152 (2025)

[9] A. Vartjees et al., Newton 1, 100017 (2025)