Patent ID: 7253654

Claim:
A device comprising: a plurality of qubits, wherein each qubit in said plurality of qubits comprises a superconducting loop interrupted by a plurality of Josephson junctions, each Josephson junction in said plurality of Josephson junctions interrupting a different portion of the superconducting loop and each different adjacent pair of Josephson junctions in said plurality of Josephson junctions defining a different superconducting island in a plurality of superconducting islands in said superconducting loop, the plurality of superconducting islands including a first superconducting island and a second superconducting island; a first capacitance; a second capacitance; and a plurality of readout mechanisms, wherein: said first and second superconducting island of each respective qubit in said plurality of qubits is coupled to a corresponding readout mechanism in said plurality of readout mechanisms such that the corresponding readout mechanism applies an equal and symmetrically canceling back-action to said first island and said second island; and a first qubit and a second qubit in said plurality of qubits are coupled to each other by said first capacitance and said second capacitance, wherein the first capacitance couples the first island of the first qubit and second qubit; and the second capacitance couples the second island of the first qubit and second qubit.