Intel unveils details of cryogenic quantum computing control chip

Technology News | February 24, 2020

By Rich Pell

Test and Measurement IoT Analog Interconnect & cables PLDs/FPGAs/ASICs Memory & Data Storage Boards & Embedded Cards MPUs/MCUs Power Management Materials & processes RF transmission Digital Signal Processing Wireless Communications

The Horse Ridge control chip is designed to be able to sit inside the quantum refrigerator used in many quantum computers and allow all the computations to be controlled from inside the refrigerator, removing a major bottleneck toward realizing commercial-scale quantum computing – interconnects and control electronics. The new research paper unveils key technical capabilities of Horse Ridge that address fundamental challenges in building a quantum system powerful enough to demonstrate quantum practicality: scalability, flexibility, and fidelity.

Horse Ridge, says the company, is designed to greatly simplify today’s complex control electronics required to operate such a quantum system by using a highly integrated system-on-chip (SoC) for faster setup time, improved qubit performance, and efficient scaling to larger qubit counts required for quantum computing to solve practical, real-world applications. The research paper includes the following key technical details:

Scalability: The integrated SoC design, implemented using the company’s 22-nm FFL (FinFET Low Power) CMOS technology, integrates four radio frequency (RF) channels into a single device. Each channel is able to control up to 32 qubits 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. Leveraging these four channels, Horse Ridge can potentially control up to 128 qubits with a single device, substantially reducing the number of cables and rack instrumentations 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, the company 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 various frequencies leveraged with Horse Ridge can be “tuned” 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 to 7 GHz, while spin qubits operate around 13 to 20 GHz. The company is exploring silicon spin qubits, which have the potential to operate at temperatures as high as 1 kelvin. This research, says the company, 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.

“Today, quantum researchers work with just a small number of qubits, using smaller, custom-designed systems surrounded by complex control and interconnect mechanisms.” says Jim Clarke, director of quantum hardware, Intel Labs. “Intel’s Horse Ridge greatly minimizes this complexity. By systematically working to scale to thousands of qubits required for quantum practicality, we’re continuing to make steady progress toward making commercially viable quantum computing a reality in our future.”

The paper presented at ISSCC is titled “A Scalable Cryo-CMOS 2-to-20GHz Digitally Intensive Controller for 4×32 Frequency Multiplexed Spin Qubits/Transmons in 22nm FinFET Technology for Quantum Computers.” For more details on the cryo-CMOS controller chip, see the company’s News Fact Sheet on Horse Ridge.

Intel
QuTech