Intel and Qutech demo 2-qubit compute with Horse Ridge chip

Intel's Horse Ridge chip, introduced in 2019, was used by Intel and partner Qutech to demonstrate two-qubit quantum computing. It opens the door to a fully integrated silicon-based quantum computer, they claimed. (Marieke de Lorijn)


Intel and Qutech researchers have successfully demonstrated for the first time two-qubit quantum computing capabilities using Intel’s Horse Ridge control processor.

The achievement was published Wednesday in the Nature Machine Intelligence journal after first being submitted by 26 author/researchers in October.

Their findings “open up the way towards a fully integrated, scalable silicon-based quantum computer,” the authors said in the research abstract.

They noted that a key challenge to large-scale quantum computing has been what is known as “interconnect complexity,” which Intel has identified in the past as a key impediment to the advancement of quantum computing because such computers have largely operated in expensive and elaborate laboratories where super-cold is required. So far, the computations from a quantum computer in super cold have not transferred easily to computers operating at room temperature.

“An important interconnect bottleneck appears between the quantum chip in a dilution refrigerator and room-temperature electronics,” the researchers noted.

Using Horse Ridge, a cryogenically tolerant CMOS (Complementary metal oxide semiconductor) control chip operating at just 3 kelvin (negative 454 degrees F.) the researchers were able to force microwave bursts to drive silicon quantum bits that were cooled to 20 millikelvin (nearly absolute zero, which is negative 459.67 degrees F.)

Running an industry standard benchmark test, the researchers achieved 99.99 % fidelity with commercial room temperature electronics used to control a two-qubit processor.

Horse Ridge control qubits encoded in the spin of single electrons confined in silicon quantum dots achieved “the same fidelity as commercial instruments at room temperature,” they said.

The researchers also used a simple two-bit algorithm used on quantum computers known as Deutsch-Jozsa to showcase Horse Ridge’s  programmability, proving its ability to control multiple qubits on a single radio frequency, known as multiplexing. Horse Ridge was designed for multiplexing, but until the latest research, multiplexing had not been proven possible, Intel said.

Intel said in a statement that the research indicates it may be possible to fully integrate a controller chip like Horse Ridge on the same die or package, which would relieve wiring bottlenecks and solve a roadblock toward scalability with quantum computing.

Horse Ridge was first introduced in late 2019 as a means to speed up development of full-stack quantum computing systems. It is fabricated using Intel’s 22nm FinFET Low Power technology.

In February 2020, Intel said its Horse Ridge chip could control 128 qubits, up from the 50 qubits of some prior systems. The ultimate goal is to control many thousands or millions of qubits.

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