  Solving random subset sum instances plays an important role in constructing
cryptographic systems. For the random subset sum problem, in 2013 Bernstein et
al. proposed a quantum algorithm with heuristic time complexity
$\widetilde{O}(2^{0.241n})$, where the "$\widetilde{O}$" symbol is used to omit
poly($\log n$) factors. In 2018, Helm and May proposed another quantum
algorithm that reduces the heuristic time and memory complexity to
$\widetilde{O}(2^{0.226n})$. In this paper, a new quantum algorithm is
proposed, with heuristic time and memory complexity
$\widetilde{O}(2^{0.209n})$.
