Cryogenic chip could enable viable quantum computers

Intel Labs has unveiled what is believed to be a first-of-its-kind cryogenic control chip — code-named ‘Horse Ridge’ — which should help speed up development of full-stack quantum computing systems.

Developed together with Intel’s research collaborators at QuTech, a partnership between the Delft University of Technology (TU Delft) and the Netherlands Organisation for Applied Scientific Research (TNO), Horse Ridge is expected to enable control of multiple quantum bits (qubits) and set a clear path towards scaling larger systems. It is fabricated in-house using Intel’s 22 nm FinFET technology, which will accelerate the company’s ability to design, test and optimise a commercially viable quantum computer.

To date, researchers have been focused on building small-scale quantum systems to demonstrate the potential of quantum devices. In these efforts, researchers have relied on existing electronic tools and high-performance computing rack-scale instruments to connect the quantum system inside the cryogenic refrigerator to the traditional computational devices regulating qubit performance and programming the system.

These devices are often custom-designed to control individual qubits, requiring hundreds of connective wires into and out of the refrigerator in order to control the quantum processor. Intel realised that this extensive control cabling for each qubit will hinder the ability to scale the quantum system to the hundreds or thousands of qubits required to demonstrate quantum practicality, not to mention the millions of qubits required for a commercially viable quantum solution.

With Horse Ridge, Intel simplifies the control electronics required to operate a quantum system, enabling the company to control multiple qubits. Replacing these bulky instruments with a highly integrated system-on-chip (SoC) should simplify system design and allow for sophisticated signal processing techniques to accelerate set-up time, improve qubit performance and enable the system to efficiently scale to larger qubit counts.

Horse Ridge is a highly integrated, mixed-signal SoC that brings the qubit controls into the quantum refrigerator — as close as possible to the qubits themselves. It effectively reduces the complexity of quantum control engineering from hundreds of cables running into and out of a refrigerator to a single, unified package operating near the quantum device.

Designed to act as a radio frequency (RF) processor to control the qubits operating in the refrigerator, Horse Ridge is programmed with instructions that correspond to basic qubit operations. It translates those instructions into electromagnetic microwave pulses that can manipulate the state of the qubits.

“While there has been a lot of emphasis on the qubits themselves, the ability to control many qubits at the same time had been a challenge for the industry,” said Intel’s Director of Quantum Hardware, Jim Clarke.

“Intel recognised that quantum controls were an essential piece of the puzzle we needed to solve in order to develop a large-scale commercial quantum system. That’s why we are investing in quantum error correction and controls. With Horse Ridge, Intel has developed a scalable control system that will allow us to significantly speed up testing and realise the potential of quantum computing.”

Horse Ridge was designed to operate at cryogenic temperatures (approximately 4 K) — a particularly exciting feat as Intel progresses its research into silicon spin qubits, which have the potential to operate at slightly higher temperatures than current quantum systems require. Today, a quantum computer operates in the mK range — just a fraction of a degree above absolute zero — but silicon spin qubits have properties that could allow them to operate at 1 K or higher temperatures, which would dramatically reduce the challenges of refrigerating the quantum system.

As research progresses, Intel aims to have cryogenic controls and silicon spin qubits operate at the same temperature level. This will enable the company to leverage its expertise in advanced packaging and interconnect technologies to create a solution with the qubits and controls in one streamlined package.

Image caption: Stefano Pellerano, Principal Engineer at Intel Labs, holds Horse Ridge. Image credit: Walden Kirsch/Intel Corporation.

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