Local Realism of Macroscopic Correlations

Abstract

We show that for macroscopic measurements which cannot reveal full information about microscopic states of the system, the monogamy of Bell inequality violations present in quantum mechanics implies that practically all correlations between macroscopic measurements can be described by local realistic models. Our results hold for sharp measurement and arbitrary closed quantum systems.

Detecting genuine multipartite entanglement of pure states with bipartite correlations

“…Monogamy was also employed in studies of quantum marginal problem, i.e. conditions for existence of a global quantum state given its marginals [10], security of quantum key distribution [11], and to show that correlations between macroscopic measurements ought to be classical [12]. It leads to efficient methods of solving strongly correlated multipartite quantum lattice systems [13].…”

Macroscopic limit of nonclassical correlations

“…We generalise our previous result [2], which applies only to quantum systems, and show that average values of macroscopic measurements on a bipartite system of 2N particles, whose correlations are described by generalised probabilistic theories, admit a local and realistic description. In particular, we show that for two measurements per observer for N ≥ 2 there exists a joint probability distribution (JPD) for all observables [14] reproducing measurable average values.…”

“…Following previous works [1][2][3][4][5][6][7][8][9][10][11][12], it is a collective measurement of the same property on all N particles, i.e.,…”

“…The above problem has been considered in literature before, see for example [1][2][3][4][5][6][7][8][9][10][11][12]. In particular, it was shown that in the macroscopic limit, where measurements are limited to reveal only average values [2] and its fluctuations [1], collective quantum correlations become local, although individual pairs of particles can manifest nonlocality.…”

“…In particular, it was shown that in the macroscopic limit, where measurements are limited to reveal only average values [2] and its fluctuations [1], collective quantum correlations become local, although individual pairs of particles can manifest nonlocality. It is still an open question whether similar macroscopic locality [1] also holds for stronger than quantum correlations [13].…”