Financial support from MINECO/AEI/FEDER through projects EPheQuCS FIS2016-78010-P, CSIC Re-search Platform PTI-001, the PIE project 202050E098, the Maria de Maeztu Program for Units of Excellencein R&D (MDM-2017-0711), and funding from CAIB PhD program is acknowledged.
We acknowledge the Spanish State Research Agency,through the Severo Ochoa and Maria de Maeztu Programfor Centers and Units of Excellence in R&D (MDM-2017-0711), CSIC extension to EPheQuCS (FIS2016-78010-P),and CSIC Quantum Technologies PTI-001. The work ofMCS has been supported by MICINN/AEI/FEDER andthe University of the Balearic Islands through a ”Ramony Cajal Fellowship (RYC-2015-18140). VP acknowledgesfinancial support from the European Research Council under the Consolidator Grant COQCOoN (Grant No.820079).