Hardware
IBM links two 120-qubit chips with four couplers, reports 99% transfer fidelity
IBM researchers connected two 120-qubit (physical) superconducting chips using four L-shaped couplers, each 80 centimeters long and made of superconducting aluminum, and transmitted qubit states between the processors. Average transfer fidelity was 99%, with a peak of 99.29%, according to ScienceAlert's report on the work. The couplers lost little energy, kept working after three heating and cooling cycles, and carried quantum entanglement between the chips; the authors call it the first multichannel quantum connection between large superconducting processors. The team also recorded magnetic interference that affected signal quality, and the study is a preprint on arXiv that has not yet been peer reviewed.
Why it mattersLinking several chips is one way to scale quantum systems without packing more qubits onto a single processor. IBM says its goal is to combine hundreds of quantum chips into a fault-tolerant quantum computer by 2029, and the researchers say further efficiency improvements are needed for practical use.