A quantum circuit assembly comprising: a first flux qubit (12,32), having at least two potential energy minima; a second flux qubit (14, 34), having at least two potential energy minima, such that a system formed by the first qubit and the second qubit has at least four potential energy minima prior to coupling, each of the four potential energy minima containing at least one eigenstate of a system comprising the first flux qubit and the second flux qubit; and a coupler (16, 40) configured to create a first tunneling path between a first potential energy minimum of the system and a second potential energy minimum of the system, and a second tunneling path between a third potential energy minimum of the system and a fourth potential energy minimum of the system, the coupler creating the first and second tunneling paths between potential energy minima representing states of equal bit parity, such that the first potential energy minimum represents the state |01〉, the second potential energy minimum represents the state |10〉, the third potential energy minimum represents the state |00〉, and the fourth potential energy minimum represents the state |11〉, wherein the coupler comprises a plurality of Josephson junctions and a capacitor that is operatively connected to each of the first flux qubit and the second flux qubit and having a capacitance selected to decrease a spread of a wave function of the system to decouple the first potential energy minimum of the system and the second potential energy minimum of the system from the third potential energy minimum of the system and the fourth potential energy minimum of the system. a first flux qubit (12,32), having at least two potential energy minima; a second flux qubit (14, 34), having at least two potential energy minima, such that a system formed by the first qubit and the second qubit has at least four potential energy minima prior to coupling, each of the four potential energy minima containing at least one eigenstate of a system comprising the first flux qubit and the second flux qubit; and a coupler (16, 40) configured to create a first tunneling path between a first potential energy minimum of the system and a second potential energy minimum of the system, and a second tunneling path between a third potential energy minimum of the system and a fourth potential energy minimum of the system, the coupler creating the first and second tunneling paths between potential energy minima representing states of equal bit parity, such that the first potential energy minimum represents the state |01〉, the second potential energy minimum represents the state |10〉, the third potential energy minimum represents the state |00〉, and the fourth potential energy minimum represents the state |11〉, wherein the coupler comprises a plurality of Josephson junctions and a capacitor that is operatively connected to each of the first flux qubit and the second flux qubit and having a capacitance selected to decrease a spread of a wave function of the system to decouple the first potential energy minimum of the system and the second potential energy minimum of the system from the third potential energy minimum of the system and the fourth potential energy minimum of the system.