Today at the International Solid State Circuits Conference, which runs through this week in San Francisco, Intel and QuTech — a partnership between Delft University of Technology and TNO (Netherlands Organization for Applied Scientific Research) — are unveiling the technical designs for a first-of-its-kind cryogenic control chip for quantum computing, which they call Horse Ridge.

Intel Labs and QuTech researchers outlined the technical features of the new cryogenic quantum control chip in a research paper. They designed the scalable system-on-chip (SOC) to operate at cryogenic temperatures, simplifying the control electronics and interconnects required to elegantly scale and operate large quantum computing systems.

Horse Ridge addresses fundamental challenges in building a quantum system powerful enough to demonstrate quantum practicality — scalability, flexibility, and fidelity.

The challenge of quantum computing is that right now, it only really works at near-freezing temperatures. Intel is trying to change that, but the control chip is a step toward enabling control at very low temperatures, as it eliminates hundreds of wires going into a refrigerated case that houses the quantum computer.

Currently, quantum researchers are working with just a small number of qubits, or quantum bits, using smaller, custom-designed systems surrounded by complex control and interconnect mechanisms. Intel’s Horse Ridge greatly minimizes this complexity.

By systematically working to scale to thousands of qubits required for quantum practicality, Intel is making steady progress toward making commercially viable quantum computing a reality, Jim Clarke, director of quantum hardware at Intel Labs, said in a statement.

Why it’s important

Jim Clarke, Intel Corporation’s director of quantum hardware, holds an Intel 49-qubit quantum test chip, called “Tangle Lake,” in front of a dilution refrigerator at QuTech’s quantum computing lab inside Delft University of Technology in July 2018. QuTech at Delft University of Technology is Intel Corporation’s quantum computing research partner in the Netherlands.

Above: Jim Clarke, Intel’s director of quantum hardware, holds an Intel 49-qubit quantum test chip, called Tangle Lake, in front of a dilution refrigerator at QuTech’s quantum computing lab inside Delft University of Technology in July 2018.

Image Credit: Tim Herman/Intel

The quantum research community is still at mile one of a marathon toward quantum practicality. Applying quantum computing to real-world problems relies first and foremost on the ability to scale to, and control, thousands of qubits at the same time, with high levels of fidelity.

Intel said Horse Ridge simplifies the complex control electronics currently required to operate such a quantum system by using a highly integrated SOC for faster set-up time, improved qubit performance, and efficient scaling to the larger qubit counts practical applications require.

The ISSCC paper highlights technical details in three key areas:

Scalability: The integrated SoC design, implemented using Intel’s 22-nanometer FinFET Low Power CMOS technology, integrates four radiofrequency (RF) channels into a single device. Each channel is able to control up to 32 qubits by leveraging “frequency multiplexing” — a technique that divides the total bandwidth available into a series of non-overlapping frequency bands, each of which is used to carry a separate signal. With these four channels, Horse Ridge can potentially control up to 128 qubits with a single device, substantially reducing the number of cables and rack instrumentation previously required.

Fidelity: Increases in qubit count trigger other issues that challenge the capacity and operation of the quantum system. One such potential impact is a decline in qubit fidelity and performance. In developing Horse Ridge, Intel optimized the multiplexing technology that enables the system to scale and reduce errors from “phase shift” — a phenomenon that can occur when controlling many qubits at different frequencies, resulting in crosstalk among qubits. The engineers can tune various frequencies leveraged with Horse Ridge with high levels of precision, enabling the quantum system to adapt and automatically correct for phase-shift when controlling multiple qubits with the same RF line, improving qubit gate fidelity.

Flexibility: Horse Ridge can cover a wide frequency range, enabling control of both superconducting qubits (known as transmons) and spin qubits. Transmons typically operate around 6-7GHz, while spin qubits operate around 13-20GHz. Intel is exploring silicon spin qubits, which have the potential to operate at temperatures as high as 1 degree Kelvin. This research paves the way for integrating silicon spin qubit devices and the cryogenic controls of Horse Ridge to create a solution that delivers the qubits and controls in one streamlined package.

Intel and QuTech will present their paper on the subject at 1:30 p.m. Pacific time on Tuesday at ISSCC.

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