System, including methods, apparatus, and compositions, for performing amplification assays with an amplification reporter including a first oligomer and a second oligomer capable of base-pairing with one another below a melting temperature of the reporter. The reporter may have a detectable photoluminescence that is affected, such as reduced, by base-pairing of the first and second oligomers with one another. A target, such as a nucleic acid target sequence, may be amplified in at least one volume, such as a plurality of partitions, above the melting temperature, and photoluminescence of the reporter may be detected from the at least one volume below the melting temperature. A property of the target, such as a concentration of the target, may be determined based on the photoluminescence detected.