Dynamics-based certification of quantumness

Dynamics-based certification of quantumness

Seminar author:Valerio Scarani

Event date and time:06/15/2023 04:00:pm

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n this talk, I shall present our new technique to detect non-classicality under the assumption that the dynamics is known [1,2,3], based on an early insight by Tsirelson [4]. Most of the talk will focus on one and two harmonic oscillators, although the results can be widely generalized (we have shown them for precessing discrete systems [1], as well as for continuous systems with arbitrary time-independent Hamiltonian dynamics [3]). Among the highlights you can expect are the following:

a) The criterion is an inequality that no classical model can violate. (This is particularly unusual for entanglement of continuous variable systems [2], where most of the witnesses rely on uncertainty relations, which can be violated by imprecise or badly calibrated measurements).

b) The criterion requires a single measurement per round; and it is a quadrature measurement, thus routinely feasible. This is a major advantage over tests that require more measurements and constraining assumptions, like Leggett-Garg type tests (which require two sequential measurements and the assumption of non-invasiveness) or tests based on “contextuality” (which require the assumption that several measurements commute).

c) The states that are detected have a symmetry that makes them suitable for bosonic error correcting codes.

But most importantly, I shall insist on the main surprise: one can use the very classical dynamics of the harmonic oscillator to detect non-classicality [4].

[1] L.T. Zaw et al., hys. Rev. A 106, 032222 (2022) https://arxiv.org/abs/2204.10498

[2] P. Jayachandran et al., Phys. Rev. Lett. 130, 160201 (2023) https://arxiv.org/abs/2210.10357

[3] L.T. Zaw and V.S., https://arxiv.org/abs/2212.06017

[4] B. Tsirelson, https://arxiv.org/abs/quant-ph/0611147