Intel and QuTech, a collaboration between Delft University of Technology and the Netherlands Organization for Applied Scientific Research have published results in quantum research claiming to address the “link bottleneck” between quantum chips sitting in cryogenic dilution refrigerators and the complex room temperature electronics that control the qubits. The innovations were covered in nature, the industry’s leading science journal for peer-reviewed research, said it was a major milestone in addressing one of the greatest quantum scalability challenges with Intel’s Horse Ridge cryogenic controller chip.
Why it can matter
A major bottleneck for quantum computing lies between the quantum chip, which is stored in the dilution refrigerator at low, cryogenic temperatures, and the room temperature control electronics that control the qubits. The operation of the control electronics with high fidelity at cryogenic temperatures is the key to overcoming the so-called “connection or cabling bottleneck”. According to Intel, it took the first step to meet this challenge when it introduced Horse Ridge, a cryogenic control chip for qubits made with its 22nm FinFET low-power technology. A second generation of the chip was introduced last year. Horse Ridge aims to bring vital control functions for the operation of quantum computers into the cryogenic refrigerator – as close as possible to the qubits themselves – in order to optimize the complexity of the control wiring for quantum systems.
The latest research shows results from randomized benchmarking showing that a commercial CMOS-based cryo-controller achieves coherent control of a two-qubit processor with the same fidelity (99.7%) as room temperature electronics. This should be an important research milestone in the field of cryoelectronics for quantum computing.
Intel and QuTech demonstrated frequency division multiplexing by using the same cable to control two qubits. This is seen as a proof of concept, as each qubit is currently individually controlled via its own cable – an approach that is not scalable as the number of qubits increases. Horse Ridge aims to overcome this limitation by using multiplexing to reduce the number of radio frequency cables required for qubit control.
The research team demonstrated the programmability of the controller by running a two-qubit algorithm called the Deutsch-Jozsa algorithm, which is more efficient on a quantum computer than on a traditional computer.
The research verified by randomized benchmarking confirms Horse Ridge’s original promise as a highly integrated and scalable solution to simplify quantum control electronics and prove that the technology can be applied directly to multi-qubit algorithms and noisy medium-scale quantum devices.