The condensate of electron quadruplets is a proposed state of matter in which Cooper pairs are formed but do not exhibit long-range order, but electron quadruplets do. One example of the proposed electron quadruplet condensates is charge-4 e superconductivity. Another example is "quartic metal" phase is related to but distinct from those superconductors explained by the standard BCS theory ; rather than expelling magnetic field lines as in the Meissner effect, it generates them, a spontaneous Nernst effect that indicates the breaking of time-reversal symmetry. After the theoretical possibility was raised, observations consistent with electron quadrupling were published using hole -doped Ba 1-x K x Fe 2 As 2 in 2021.