eQASM: An Executable Quantum Instruction Set Architecture

Bridging the gap between quantum software and hardware, recent research proposed a quantum control microarchitecture QuMA which implements the quantum microinstruction set QuMIS. However, QuMIS does not offer feedback control, and is tightly bound to the hardware implementation. Also, as the number of qubits grows, QuMA cannot fetch and execute instructions fast enough to apply all operations on qubits in time. Known as the quantum operation issue rate problem, this limitation is aggravated by the low information density of QuMIS instructions. In this paper, we propose an executable quantum instruction set architecture (QISA), called eQASM, that can be translated from quantum assembly language (QASM), supports comprehensive quantum program flow control, and is executed on a quantum control microarchitecture. eQASM alleviates the quantum operation issue rate problem by efficient timing specification, single-operation-multiple-qubit execution, and a very-long-instruction-word architecture. The definition of eQASM focuses on the assembly level to be expressive. Quantum operations are configured at compile time instead of being defined at QISA design time. We instantiate eQASM into a 32-bit instruction set targeting a seven-qubit superconducting quantum processor. We validate our design by performing several experiments on a two-qubit quantum processor.