Solid-state qubits have recently advanced to the level that enables them, in principle, to be scaledup into fault-tolerant quantum computers. As these physical qubits continue to advance, meeting the challenge of realising a quantum machine will also require the engineering of new classical hardware and control architectures with complexity far beyond the systems used in today's fewqubit experiments. Here, we report a micro-architecture for controlling and reading out qubits during the execution of a quantum algorithm such as an error correcting code. We demonstrate the basic principles of this architecture in a configuration that distributes components of the control system across different temperature stages of a dilution refrigerator, as determined by the available cooling power. The combined setup includes a cryogenic field-programmable gate array (FPGA) controlling a switching matrix at 20 millikelvin which, in turn, manipulates a semiconductor qubit.Realising the classical control system of a quantum computer is a formidable scientific and engineering challenge in its own right 1,2 . The hardware that comprises the control interface must be fast relative to the timescales of qubit decoherence, low-noise so as not to further disturb the fragile operation of qubits, and scalable with respect to physical resources, ensuring that the footprint for routing signal lines or the operating power does not grow rapidly as the number of qubits increases 3,4 . As solid-state quantum processors will likely operate below 1 kelvin 5-8 , components of the control system will also need to function in a cryogenic environment, adding further constraints.Similar challenges have long been addressed in the satellite and space exploration community 9 , where the need for high-frequency electronic systems operating reliably in extreme environments has driven the development of new circuits and devices 10 . Quantum computing systems, on the other hand, have to date largely relied on brute-force approaches, controlling a few qubits directly via room temperature electronics that is hardwired to the quantum device at cryogenic temperatures.Here we present a control architecture for operating a cryogenic quantum processor autonomously and demonstrate its basic building blocks using a semiconductor qubit. This architecture addresses many aspects related to scalability of the control interface by embedding multiplexing sub-systems at cryogenic temperatures and separating the high-bandwidth analog control waveforms from the digital addressing needed to select qubits for manipulation. Our demonstration comprises a commercial field-programmable gate array (FPGA) operating at 4 kelvin and controlling a microwave signal switching matrix at 20 mK, which then interfaces with a quantum dot device. Bringing these sub-systems together in the context of our control architecture suggests a path for scaleup of control hardware needed to manipulate the large numbers of qubits in a useful quantum machine. I. CONTROL MICRO-ARCHITECTUREOur control micro-...

We describe the operation of a cryogenic instrumentation platform incorporating commercially available field-programmable gate arrays (FPGAs). The functionality of the FPGAs at temperatures approaching 4 K enables signal routing, multiplexing, and complex digital signal processing in close proximity to cooled devices or detectors within the cryostat. The performance of the FPGAs in a cryogenic environment is evaluated, including clock speed, error rates, and power consumption. Although constructed for the purpose of controlling and reading out quantum computing devices with low latency, the instrument is generic enough to be of broad use in a range of cryogenic applications.

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