A quantum mechanical credit unit includes a plurality of qubit strings stored in computer readable storage media and configured for comparison with challenge questions during a verification procedure. The plurality of qubit strings is stored in at least k registers where k is a selected security number for the credit unit. An information register stores information about qubit strings that remain unused to provide the used qubit strings during the verification procedure. A unique serial number is configured to identify the credit unit without association with its holder or the qubit strings. Issuance and verification methods for the credit unit are also disclosed.