The overall goal of this project was to develop and experimentally validate algorithmic, field-programmable gate array (FPGA)-based control of a transmon, i.e., a superconducting quantum circuit. (An FPGA is an integrated circuit designed to be configured by a customer or a designer after manufacturing using a hardware description language). Although we were not able to conduct the final control experiments, we did develop a significant new capability to design advanced algorithms for specific physics tasks and then efficiently implement them on an FPGA. These algorithms are calculated with sub-microsecond latencies, in particular weak measurement phase estimation in 112 ns and Bayesian estimation of qubit state probabilities every 160 ns. Experimental measurements with a qubit system validate real time weak measurements on the FPGA and demonstrate the validity of the Bayesian estimation of quantum trajectories.
This project supports Lawrence Livermore National Laboratory investments in quantum sensing, simulation, and computation as part of the DOE National Strategic Computing Initiative. It is relevant to R&D priorities in National Security community support for breakthrough technologies and computational science and engineering. Although our algorithms were developed with a specific physics experiment in mind, two aspects of our achievements are broadly applicable. First, Bayesian estimation on an FPGA has a wide range of potential applications outside the quantum computing sphere. Second, we have a significant knowledge base of HDLCoder operation, which is directly applicable to other FPGA projects at Livermore.
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