Leggett-Garg tests for macrorealism: Interference experiments and the simple harmonic oscillator

Leggett-Garg (LG) tests for macrorealism were originally designed to explore quantum coherence on the macroscopic scale. Interference experiments and systems modeled by harmonic oscillators provide useful examples of situations in which macroscopicity has been approached experimentally are readily turned into LG a single dichotomic variable $Q$. Applying this approach double-slit experiment noninvasive measurement at slits is included, we exhibit violations. We find that these violations always accompanied destructive interference. The converse not true general there nontrivial regimes interference but two-time inequalities satisfied, implies it fact often possible assign (indirectly determined) probabilities interferometer paths. Similar features have observed recent work involving analysis Mach-Zehnder compare with those results. extend triple-slit again finding violations, also some surprising relationships between NSIT conditions do exist variables. For simple oscillator, an analytically tractable example showing violation gaussian initial state, echoing simpler form results Bose et al. [Phys. Rev. Lett. 120, 210402 (2018)].