- #1
- 8,498
- 2,128
You got to love this! A top experimental team was assembled to test the "freedom of choice" loophole (if you can call it that). Usually, when random settings are needed in a Bell test, a computer generated value is obtained (pseudo random), or similar. This is relatively "local", and subject to the assertion that something is preventing free choice of settings for the Bell test. In this clever version, light from distant stars is used as an input to select setting values. Then a Bell test is performed. Check it out:
https://arxiv.org/abs/1611.06985
Bell's theorem states that some predictions of quantum mechanics cannot be reproduced by a local-realist theory. That conflict is expressed by Bell's inequality, which is usually derived under the assumption that there are no statistical correlations between the choices of measurement settings and anything else that can causally affect the measurement outcomes. In previous experiments, this "freedom of choice" was addressed by ensuring that selection of measurement settings via conventional "quantum random number generators" (QRNGs) was space-like separated from the entangled particle creation. This, however, left open the possibility that an unknown cause affected both the setting choices and measurement outcomes as recently as mere microseconds before each experimental trial. Here we report on a new experimental test of Bell's inequality that, for the first time, uses distant astronomical sources as "cosmic setting generators." In our tests with polarization-entangled photons, measurement settings were chosen using real-time observations of Milky Way stars while simultaneously ensuring locality. We observe statistically significant ≳11.7σ and ≳13.8σ violations of Bell's inequality with estimated p-values of ≲7.4×10−32 and ≲1.1×10−43, respectively, thereby pushing back by ∼600 years the most recent time by which any local-realist influences could have engineered the observed Bell violation.
https://arxiv.org/abs/1611.06985
Bell's theorem states that some predictions of quantum mechanics cannot be reproduced by a local-realist theory. That conflict is expressed by Bell's inequality, which is usually derived under the assumption that there are no statistical correlations between the choices of measurement settings and anything else that can causally affect the measurement outcomes. In previous experiments, this "freedom of choice" was addressed by ensuring that selection of measurement settings via conventional "quantum random number generators" (QRNGs) was space-like separated from the entangled particle creation. This, however, left open the possibility that an unknown cause affected both the setting choices and measurement outcomes as recently as mere microseconds before each experimental trial. Here we report on a new experimental test of Bell's inequality that, for the first time, uses distant astronomical sources as "cosmic setting generators." In our tests with polarization-entangled photons, measurement settings were chosen using real-time observations of Milky Way stars while simultaneously ensuring locality. We observe statistically significant ≳11.7σ and ≳13.8σ violations of Bell's inequality with estimated p-values of ≲7.4×10−32 and ≲1.1×10−43, respectively, thereby pushing back by ∼600 years the most recent time by which any local-realist influences could have engineered the observed Bell violation.
In case anyone is disappointed that Bell test loopholes are being tightened or closed.
