Quantum processors and quantum computers employ principles of quantum mechanics to analyse, process, store and protect information. Therefore, quantum processing and computing, operating using superposition, will revolutionise our conventional way of data processing and computing in speed, power, and security, which will affect our lives, economy, and security in national and international quantities. Superconducting quantum processors on large scale with a number of quantum bits, rather than classical bits, of more than 500, are one of the most promising platforms to realise quantum computers. The quantum state of these processors, commonly known as coherence in superconducting transmons, is fragile to weak environmental perturbations such as imperfection in materials, current noise in the quantum chip, or heat load associated with the transmon qubits control and read-out electronics. In this three years project, our team together with our project partners aim at: (i) developing a new type of qubits that are controlled and addressed by the gate voltage, rather than conventional transmons that are operating based on current flux control lines. Our proposed qubit is known as gatemon and we aim to fabricate them on large scale in a low-loss silicon chip. Each individual gatemon will be shunted by a parallel plate capacitor in a single quantum chip. Our strategy to integrate our gatemons on large scale is to use low-loss two-dimensional materials to build the shunted capacitors. Such technology would allow us to miniaturise the footprint of our gatemon quantum chips by > 2000 times smaller. The gatemon chips will be operated at the 10mK stage of a dilution refrigerator. All fabrication and measurements will take place at the University of Glasgow James Watt Nanofabrication Centre (JWNC), and at the Centre for Quantum Technology. (ii) developing a proof of concept modern electronics that can work at low temperatures, known as cryogenic electronics based on CMOS electronics. The chips will be mounted at the 3K stage of the dilution refrigerator to control and readout the gatemon quantum chips. (iii) training and educating a diverse cohort of next-generation UK quantum technology students, academics, and engineers promoting capability in a research field with significant national and international economic potential and interests but with significant employment shortage. The outputs of the SEQUENCE project will deliver a major breakthrough to quantum computing science and technology, advance low-power and reliable devices for cryoelectronic applications, and allow the technological relevance of our work to be placed on a sound footing in the industrial context.

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.

"Semiconductors" are synonymous with "Silicon chips". After all Silicon supported computing technologies in the 20th century. But Silicon is reaching fundamental limits and already many of the technologies we take for granted are only possible because of Compound Semiconductors (CS). These include: the internet, smart phones and energy-efficient LED lighting! CSs are also at the heart of most of the new technologies envisaged, including 6G wireless, ultra-high speed optical fibre connectivity, LIDAR for autonomous vehicles, high voltage switching for electric vehicles, the IoT and high-capacity data storage. CSs also offer huge opportunities for energy efficiency and net zero. The CS Hub will contribute to "Engineering Net Zero", through products, such as energy-efficient electronics, and by introducing new environmentally-friendly manufacturing processes; to "Quantum Technologies", by creating practical implementations that can be manufactured at scale; to the "Physical and Mathematical Sciences Powerhouse" and "Frontiers in Engineering and Technology", through e.g. cutting-edge materials science and manufacturing-process innovation. CS materials are grown atom-by-atom on slices of crystalline material, known as substrates, which provide mechanical support for the resulting "wafer" during the next stage of fabrication. CSs are often made on relatively small substrates. Manufacturers have had to combine functions by assembling discrete devices but this is expensive. New approaches to integration in epitaxy and fabrication are required along with wafer-size scale-up for the new applications. Applications such as in quantum technology (QT) are pushing requirements for more accurate and highly reproducible manufacturing-processes. With such improvements CS will underpin the UK quantum industry and enable impact for the existing QT investments. We will create designs that are more tolerant to typical variations that occur during manufacturing; develop manufacturing processes that are more uniform and repeatable; create techniques to characterise performance part-way through manufacturing, create techniques to combine materials (e.g. CS grown atom-by-atom on Silicon) and combine functions on chip. We will study and implement ways to make CS manufacturing more environmentally friendly. We will make it easier to compare the environmental foot-print of different CS research and manufacturing-processes by making available relevant, high quality data in the form of accessible libraries of the resource and energy usage of the feedstocks and processes used in CS manufacturing. We aim to change the mind-set of UK academics. Our vision is that researchers think about the translation of their research from the beginning of the innovation process and about the requirements that next generation product manufacturers will face. As a critical factor in all future manufacturing, we aim to embed the philosophy of resource efficiency of the research itself, resource efficiency of the manufacturing process, as well as of the application it supports. We aim to repatriate and connect CS manufacturing supply chains to re-shore production and facilitate innovation, enabling development of holistic solutions. We will address the current staffing shortages of the CS industry by: providing leadership in improving career structure and enhancing training for Hub research and technical staff; putting in place the very best ED&I practice to create the most positive and inclusive working environment and promulgating this across the industry; inspiring the next generation of the CS workforce as well as spreading the news about the fantastic career opportunities currently available. By working closely with industry partners on all these aspects we will attract and retain staff in this critical UK manufacturing industry.