Randomness and Locality in Quantum Mechanics

Ingemar Nordin

Antoine Suárez

It is argued that the quantum correlations are not maximally nonlocal to make it possible to control local outcomes from outside spacetime, and quantum mechanics emerges from timeless nonlocality and biased local randomness. This rules out a world described by NL (nonlocal) boxes. A new type of experiments is suggested.

Md. Rajjak Gazi, Ashutosh Rai, Samir Kunkri +1 more

Study of non-local correlations in terms of Hardy's argument has been quite popular in quantum mechanics. Hardy's non-locality argument depends on some kind of asymmetry, but a two-qubit maximally entangled state, being symmetric, does not exhibit this kind of non-locality. Here we ask the following question: can this feature be explained by some principle outside quantum mechanics? The no-signaling condition does not provide a solution. But, interestingly, the information causality principle (Pawlowski et al 2009 Nature 461 1101) offers an explanation. It shows that any generalized probability theory which gives completely random results for local dichotomic observable, cannot provide Hardy's non-local correlation if it is restricted by a necessary condition for respecting the information causality principle. In fact, the applied necessary condition imposes even more restrictions on the local randomness of measured observable. Still, there are some restrictions imposed by quantum mechanics that are not reproduced from the considered information causality condition.

Michael J. W. Hall

Dong-Ling Deng, Chong Zu, Chang, X. -Y. +4 more

Random numbers represent an indispensable resource for many applications. A recent remarkable result is the realization that non-locality in quantum mechanics can be used to certify genuine randomness through Bell's theorem, producing reliable random numbers in a device independent way. Here, we explore the contextuality aspect of quantum mechanics and show that true random numbers can be generated using only single qutrit (three-state systems) without entanglement and non-locality. In particular, we show that any observed violation of the Klyachko-Can-Binicioglu-Shumovsky (KCBS) inequality [Phys. Rev. Lett. 101, 20403 (2008)] provides a positive lower bound on genuine randomness. As a proof-of-concept experiment, we demonstrate with photonic qutrits that at least 5246 net true random numbers are generated with a confidence level of 99.9%.

Gábor Cśanyi