  To bridge the gap between limited hardware access and the huge demand for
experiments for Noisy Intermediate-Scale Quantum (NISQ) computing system study,
a simulator which can capture the modeling of both the quantum processor and
its classical control system to realize early-stage evaluation and design space
exploration, is naturally invoked but still missing. This paper presents SANQ,
a Simulation framework for Architecting NISQ computing system. SANQ consists of
two components, 1) an optimized noisy quantum computing (QC) simulator with
flexible error modeling accelerated by eliminating redundant computation, and
2) an architectural simulation infrastructure to construct behavior models for
evaluating the control systems. SANQ is validated with existing NISQ quantum
processor and control systems to ensure simulation accuracy. It can capture the
variance on the QC device and simulate the timing behavior precisely (<1% and
10% error for various real control systems). Several potential applications are
proposed to show that SANQ could benefit the future design of NISQ compiler,
architecture, etc.
