Intel and QuTech, a collaboration between Delft University of Technology and the Netherlands Organisation for Applied Scientific Research, have published findings in quantum research that claims to address the “interconnect bottleneck” that exists between quantum chips that sit in cryogenic dilution refrigerators and the complex room-temperature electronics that control the qubits. The innovations were covered in Nature, the industry-leading science journal of peer-reviewed research, and said to mark an important milestone in addressing one of the biggest challenges to quantum scalability with Intel’s cryogenic controller chip Horse Ridge.
Why it may matter
A key bottleneck for quantum computing lies between the quantum chip stored in low, cryogenic temperatures in dilution refrigerator and room-temperature control electronics that control the qubits. Getting the control electronics to operate at high fidelity at cryogenic temperatures is key to overcoming what is referred to as the “interconnect or wiring bottleneck.” According to Intel, it took the first step to address this challenge when it introduced Horse Ridge, a cryogenic control chip for qubits built using its 22nm FinFET Low Power technology. A second generation of the chip was introduced last year. Horse Ridge aims to bring key control functions for quantum computer operation into the cryogenic refrigerator – as close as possible to the qubits themselves – to streamline the complexity of control wiring for quantum systems.
The latest research demonstrates results from randomized benchmarking that show a commercial CMOS-based cryo-controller achieving coherent control of a two-qubit processor at the same levels of fidelity (99.7%) as room-temperature electronics. This is claimed to be a key research milestone in the field of cryo-electronics for quantum computing.
Intel and QuTech showed frequency multiplexing by using the same cable to control two qubits. This is being regarded as a proof of concept as currently each qubit is individually controlled by its own cable – an approach that is not scalable as qubit counts increase. Horse Ridge aims to solve that limitation by leveraging multiplexing to reduce the number of radio frequency cables needed 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 results, verified by randomized benchmarking, validate the original promise of Horse Ridge as a highly integrated and scalable solution for simplifying quantum control electronics, and prove that the technology can be directly applied to multi-qubit algorithms and noisy intermediate-scale quantum devices.