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Detecting quantumness and entanglement with uniform precessions

In an overlooked paper by Tsirelson, an unexpected observation was made about the quantum harmonic oscillator. Despite its time evolution being the same as its classical counterpart —a precession in phase space— its nonclassicality can be detected by probing its position at different times.

Recently, we built upon this observation to introduce a family of protocols that detect the nonclassicality of suitable states of a single quantum system, under the sole assumption that the measured dynamical observable undergoes a uniform precession. After covering the protocol for both the harmonic oscillator (uniform precession in phase space) and finite-dimensional spins (uniform precession in real space, if time permits), I will present some recent results about witnessing entanglement of uniformly-precessing systems. By utilising this criterion on the centre-of-mass motion of two harmonic oscillators, we obtain an entanglement witness that requires only quadrature measurements, but one that does not rely on quantum uncertainty relations.

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Speaker: Zaw Lin Htoo (Centre for Quantum Technologies at the National University of Singapore)

 

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