  One unique feature of quantum mechanics is the Heisenberg uncertainty
principle, which states that the outcomes of two incompatible measurements
cannot simultaneously achieve arbitrary precision. In an information-theoretic
context of quantum information, the uncertainty principle can be formulated as
entropic uncertainty relations with two measurements for a quantum bit (qubit)
in two-dimensional system. New entropic uncertainty relations are studied for a
higher-dimensional quantum state with multiple measurements, the uncertainty
bounds can be tighter than that expected from two measurements settings and
cannot result from qubits system with or without a quantum memory. Here we
report the first room-temperature experimental testing of the entropic
uncertainty relations with three measurements in a natural three-dimensional
solid-state system: the nitrogen-vacancy center in pure diamond. The
experimental results confirm the entropic uncertainty relations for multiple
measurements. Our result represents a more precise demonstrating of the
fundamental uncertainty principle of quantum mechanics.
