IBM connects two 120-qubit Nighthawk chips with superconducting cables

IBM linked two 120-qubit Nighthawk chips in one refrigerator using four 80-centimeter superconducting cables. Researchers swapped quantum states across a cable and entangled qubits on separate chips with 95% fidelity. The experiment used larger chips than earlier cross-chip entanglement demonstrations, but QuantWare physicist Simon Storz judged the fidelity too low for the chips to work as one processor.