  Recent progress in the development of superconducting nanowire single-photon
detectors (SNSPDs) has delivered excellent performances, and has had a great
impact on a range of research fields. The timing jitter, which denotes the
temporal resolution of the detection, is a crucial parameter for many
applications. Despite extensive work since their apparition, the lowest jitter
achievable with SNSPDs is still not clear, and the origin of the intrinsic
limits is not fully understood. Understanding its intrinsic behaviour and
limits is a mandatory step toward improvements. Here, we report our
experimental study on the intrinsically-limited timing jitter in molybdenum
silicide (MoSi) SNSPDs. We show that to reach intrinsic jitter, several
detector properties such as the latching current and the kinetic inductance of
the devices have to be understood. The dependence on the nanowire cross-section
and the energy dependence of the intrinsic jitter are exhibited, and the origin
of the limits are explicited. System timing jitter of 6.0 ps at 532 nm and 10.6
ps at 1550 nm photon wavelength have been obtained.
