Mode-selective couplers for frequency collision reduction

A method, comprising:

• coupling a control qubit to a first target qubit by a first mode-selective coupler that allows A-mode coupling between the control qubit and the first target qubit, and prevents B-mode coupling between the control qubit and the first target qubit;
• coupling the control qubit to a second target qubit by a second mode-selective coupler that allows the B-mode coupling between the control qubit and the second target qubit, and prevents the A-mode coupling between the control qubit and the second target qubit;
• coupling the control qubit to a third target qubit by a third mode-selective coupler that allows the A-mode coupling between the control qubit and the third target qubit, and prevents the B-mode coupling between the control qubit and the third target qubit;
• and
• coupling the control qubit to and a fourth target qubit by a fourth mode-selective coupler that allows the B-mode coupling between the control qubit and the fourth target qubit, and prevents the A-mode coupling between the control qubit and the fourth target qubit.

A computer program product for facilitating selectively coupling a control qubit to target qubits, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to:

• couple the control qubit to a first target qubit by a first mode-selective coupler that allows A-mode coupling between the control qubit and the first target qubit, and prevents B-mode coupling between the control qubit and the first target qubit;
• couple the control qubit to a second target qubit by a second mode-selective coupler that allows the B-mode coupling between the control qubit and the second target qubit, and prevents the A-mode coupling between the control qubit and the second target qubit;
• couple the control qubit to a third target qubit by a third mode-selective coupler that allows the A-mode coupling between the control qubit and the third target qubit, and prevents the B-mode coupling between the control qubit and the third target qubit;
• and
• couple the control qubit to a fourth target qubit by a fourth mode-selective coupler that allows the B-mode coupling between the control qubit and the fourth target qubit, and prevents the A-mode coupling between the control qubit and the fourth target qubit.