  The flux quantization is a key indication of electron pairing in
superconductors. For example, the well-known h/2e flux quantization is
considered strong evidence for the existence of the charge-2e, two-electron
Cooper pairs. Here we report evidence for multi-charge flux quantization in
mesoscopic ring devices fabricated using the transition-metal kagome
superconductor CsV3Sb5. We perform systematic magneto-transport measurements
and observe unprecedented quantization of magnetic flux in units of h/4e and
h/6e in magnetoresistance oscillations. Specifically, at low temperatures,
magnetoresistance oscillations with period h/2e are detected, as expected from
the flux quantization for charge-2e superconductivity. We find that the h/2e
oscillations are suppressed and replaced by resistance oscillations with h/4e
periodicity when temperature is increased. Increasing the temperature further
suppresses the h/4e oscillations and robust resistance oscillations with h/6e
periodicity emerge as evidence for charge-6e flux quantization. Our
observations provide the first experimental evidence for the existence of
multi-charge flux quanta and emergent quantum matter exhibiting higher-charge
superconductivity in the strongly fluctuating region above the charge-2e Cooper
pair condensate, revealing new insights into the intertwined and vestigial
electronic order in kagome superconductors.
