In the last decade, proof of concepts has been given and small-scale demonstrators have been built to show that the quantum devices allow obtaining unprecedented performances in practical applications. For example, dramatic enhancements can be obtained in the speed and computational power of next-generation computers (Quantum computing) using superconducting qubits. Also, disruptive performance improvements can be achieved in advanced imaging, remote sensing, long distance/secure communication (quantum cryptography) or diagnostic techniques using superconducting nanowire single-photon detectors - SNSPDs. The transition from demonstrators to practical scaled-up devices with a large number of elements is still at an early stage and a significant technological leap is required for a real breakthrough in those fields. The identified challenge in scaling-up the number of elements in quantum circuits, that is virtually identical for superconducting qubits and SNSPDs operating in Radio Frequency regime - RF-SNSPDs -, is represented by efficient multiplexing of these elements since they typically operate at cryogenic temperatures and need multiple connections for control and read-out at microwave frequencies. This makes the electronics complex, costly and difficult to scale beyond 10 to 100 of elements in the commercially available cryostats hampering their use in real-world applications. Single Flux Quantum (SFQ) electronics can operate at cryogenic temperature with unrivalled high frequency and ultra-low power consumption relying on the peculiar current to voltage relation of their basic element: the Josephson Junctions (JJ). Under proper condition, JJs generates ~2 ps width voltage pulses at repetition frequency above 500 GHz, with unprecedented time accuracy, stability and low power consumption. SFQ electronics is intrinsically scalable and we propose to use generated SFQ pulses as a source for precise and low noise frequency signals for multiplexed control and read-out of on-chip integrated qubits and RF-SNSPDs arrays. This transformative approach will allow to finally fill the gap in the existing quantum technology for a step-change at the same time in quantum science and advanced sensing applications. At this aim, we will bring together top UK expertise in nanofabrication and superconducting quantum technology, backed by a strong commitment from the UK world-leading company in SFQ electronics and quantum technologies SeeQC UK. We build on previous work carried out through Innovate UK, Marie Curie, Royal Society and European Research Council funding and make complimentary use of expertise and nanofabrication facilities to significant progress in the development of quantum technology in a 3-years targeted programme. Thanks to the strategic collaboration with National UK Quantum Technology Hubs, we will carry out joint experiments in quantum computing/simulation (Hub in Quantum computing and simulation - HQCS) and in advanced imaging (QuantIC) applications to show the game-changing nature of developed technology. Also, we will leverage support to engage closely with end-users and stakeholder maximizing the impact of the research project. Potential markets for developed technology will be exploited through the collaboration with QT hubs industry partners' network and with the strategic Industrial partners of this proposal like Kelvin Nanotechnology (KNT), Oxford Quantum Circuits (OQC) and SeeQC UK. This project is designed to generate high-quality research outputs and to deploy advanced technology in the field of quantum science. The work strongly resonates with the central themes of Horizon 2020 programmes and with the UK strategic research priorities set by Research Councils. The long-term goal is to establish a world-class experimental research programme which will have a powerful cross-disciplinary impact strengthening the UK's leading position in new science and technology to generate societal and economic benefits.

Quantum computers are superior to conventional computers for their high computing power, and this is true only if they have many qubits e.g., 100s or more. The current leading commercial players in the field have successfully demonstrated processors with more than 50 cryogenic qubits using the classical control interferences which suffer from bulky cables and electronics. Novel solutions are desperately and urgently required for qubit upscaling. Avenues for improvement include dramatically increasing the number, density and modularity of independent control channels, signal bandwidth, the time and amplitude resolution of generated waveforms, and the physical footprint of circuits and interconnects for noisy intermediate-scale quantum computing (NISQC), universal fault-tolerant quantum computing (UFTQC) and efficient multiplexing of single-photon detectors. This project will be a step towards improving the performance of and potentially revolutionising QC control hardware and future integration based on modern information and communication hardware. This will be achieved by synergising QC with ICT's state-of-the-art developments in optical, wireless and cyro-CMOS electronics. The researchers from both QC and ICT sectors will collaboratively identify, explore, develop, and benchmark the technologies at both device and system levels. Through nationwide networking chaired by NQCC with support from the University of Glasgow (UoG), National Quantum Computing Centre (NQCC), National Physical Laboratory (NPL), University College London (UCL), University of Strathclyde (UoS), and Science and Technology Facilities Council (STFC) and more than 20 industrial and academic partners, we will eventually deliver the ambitious objectives for the next generation of quantum computers with more than 100 qubits. The first 12 months of EPIQC will be dedicated to co-creation activities aimed at validating and further refining the focus of our work. The NQCC will devote a project manager to coordinate and support the co-creation activities, helping to reach the broader community and ensuring activities are delivered professionally. In the first instance, a series of one-to-one conversations will be held with end-users to validate needs and understand the market pull. This will inform further one-to-one discussions with key industry players and the identification of supply chains and pre-competitive areas of research. This groundwork will be essential to the successful set-up and definition of a series of focus groups on each of the pillars, exploring state-of-the-art, future trends and markets and defining top-level roadmaps for pre-competitive challenges. These challenges will be further explored through sandpits defining the details of research strands under each pillar. In years 2-4 EPIQC focusses on investigations of cross-disciplinary interfacing and integration of alternative control and readout architectures through three complementary pillars, and the verification of ICT-QC hardware for user needs.