Quantum coherence in the dynamical Casimir effect

7 pags., 2 figs.We propose to use quantum coherence as the ultimate proof of the quantum nature of the radiation that appears by means of the dynamical Casimir effect in experiments with superconducting microwave waveguides.We show that, unlike previously considered measurements such as entanglement and discord, quantum coherence does not require a threshold value of the external pump amplitude and is highly robust to thermal noise.Financial support from Fundación General CSIC (Programa ComFuturo) is acknowledged by C.S. Additional support from MINECO Project FIS2015-70856-P (cofinanced by FEDER funds) and CAM PRICYT Project QUITEMAD+ S2013/ICE- 2801 is also acknowledged.Peer Reviewe