We present the Sparse Synchronous model (SSM) of computation, which allows a programmer to specify software timing more precisely than the traditional “heartbeat” of mainstream operating systems or the synchronous languages. SSM is a mix of semantics inspired by discrete event simulators and the synchronous languages designed to operate in resource-constrained environments such as microcontrollers. SSM provides precise timing prescriptions, concurrency, and determinism. We implement SSM in SSML, a toy language along with a runtime system that includes a scheduler, memory manager, and an interface that works with a real-time operating system to keep the model synchronized with the real world. Experimentally, we find our implementation is able to perform jitter-free I/O in the 10s of kHz on a microcontroller.

We describe the development of a new programming language Scoria and its compiler. Scoria is a high-level reactive real-time language based on the sparse synchronous model (SSM), designed to produce time- and power-efficient low-level C code that can run on small IoT devices. While the compiler is not yet in a state where it is meaningful to measure power usage, we carefully profile the timing behaviour and identify bottlenecks that can improve performance. The language and compiler are implemented as an Embedded Domain-Specific Language (EDSL) on top of Haskell.

Practical error analysis is essential for the design, optimization, and evaluation of Noisy Intermediate-Scale Quantum(NISQ) computing. However, bounding errors in quantum programs is a grand challenge, because the effects of quantum errors depend on exponentially large quantum states. In this work, we present Gleipnir, a novel methodology toward practically computing verified error bounds in quantum programs. Gleipnir introduces the (ρ,δ)-diamond norm, an error metric constrained by a quantum predicate consisting of the approximate state ρ and its distance δ to the ideal state ρ. This predicate (ρ,δ) can be computed adaptively using tensor networks based on the Matrix Product States. Gleipnir features a lightweight logic for reasoning about error bounds in noisy quantum programs, based on the (ρ,δ)-diamond norm metric. Our experimental results show that Gleipnir is able to efficiently generate tight error bounds for real-world quantum programs with 10 to 100 qubits, and can be used to evaluate the error mitigation performance of quantum compiler transformations.

We present the Sparse Synchronous model (SSM) of computation, which allows a programmer to specify software timing more precisely than the traditional “heartbeat” of mainstream operating systems or the synchronous languages. SSM is a mix of semantics inspired by discrete event simulators and the synchronous languages designed to operate in resource-constrained environments such as microcontrollers. SSM provides precise timing prescriptions, concurrency, and determinism. We present SSM, its motivations, and details of a lightweight runtime system upon which a future language will be built.