Hannover 2016 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 16: Precision Measurements and Metrology IV (with A)
Q 16.2: Vortrag
Dienstag, 1. März 2016, 11:15–11:30, a310
Fundamental uncertainty of the speed of light in vacuum — •Daniel Braun1, Fabienne Schneiter1, and Uwe R. Fischer2 — 1Institute of Theoretical Physics, University Tübingen, 72076 Tübingen, Germany — 2Seoul National University, Department of Physics and Astronomy, Center for Theoretical Physics, 151-747 Seoul, Korea
The speed c of light in vacuum is a natural constant of crucial importance for the foundations of physics and many applications. Advanced theories predict quantum fluctuations of c or even a time-evolution. Combining arguments from quantum parameter-estimation-theory and classical general relativity, we here establish rigorously the existence of lower bounds on the precision to which c can be determined in principle. They result in minimal uncertainties of lengths measured through the propagation of light signals that are comparable to predictions from quantum gravity theory. However, the minimal uncertainties depend on the quantum state of light used for the measurement, challenging thus the idea of quantum fluctuations of geometry that exist independently of a measurement prescription. In particular, our novel, measurement-based approach predicts that fluctuations on the length scale of the Planck length are only accessible through quantum-enhanced measurements that use highly non-classical states of light.