Compact and Weakly Compact Multipliers of Locally Compact Quantum Groups

A locally compact group G is compact if and only if its convolution algebra has a non-zero (weakly) compact multiplier. Dually, G is discrete if and only if its Fourier algebra has a non-zero (weakly) compact multiplier. In addition, G is compact (respectively, amenable) if and only if the second dual of its convolution algebra equipped with the first Arens product has a non-zero (weakly) compact left (respectively, right) multiplier. We prove the non-commutative versions of these results in the case of locally compact quantum groups.