Method and system for executing a one-time program comprising at least one instruction operating on at least one input value (a, b) and returning at least one output value (O), wherein each instruction of the one-time program is encoded onto a state of an elementary quantum system, comprising: encoding the at least one input value (a, b) onto a quantum gate according to a pre-defined input-encoding scheme; applying the quantum gate to the at least one elementary quantum system; making a measurement of a resulting state of the at least one elementary quantum system after the quantum gate; and determining the at least one output value from a result of the measurement.