Intel Research has been working with QuTech to promote research on quantum hardware and software ecosystems, striving to achieve commercial applications of quantum computers in the future. Among the challenges faced by the entire industry in the field of commercial-scale quantum computing, interconnection and control electronics are the main bottlenecks.

Building a fault-tolerant commercial-scale quantum computer requires a scalable architecture for both qubits and control electronics. Horse Ridge is a highly integrated system-on-chip (SoC) that provides an ingenious solution to achieve high-fidelity control of multiple qubits, an important milestone towards quantum practicality.

What are the characteristics of Horse Ridge?

Horse Ridge is a highly integrated, mixed-signal, low-temperature system-on-chip (SoC) with a silicon area of ??4 x 4mm2 and uses Intel's 22nm FFL (FinFET Low Power) CMOS technology. Horse Ridge integrates static random access memory (SRAM), digital core and analog/radio frequency (RF) circuitry into a single package, using microwave pulses to manipulate the state of qubits in quantum systems.

Integrated high-speed digital-to-analog converters and wideband upconverters for frequencies between 2-20 gigahertz (Ghz).

Pulse-shaped amplitude and phase modulation information (18Gb/s) is stored in on-chip SRAM, supporting envelopes up to 41μs, which are informed by a look-up table (LUT), which is available for each Each qubit defines 8 instructions.

Measured Arbitrary Pulse Output Signal

Utilizing LUTs reduces the data rate required by the controller by executing an integrated programmable instruction set on an external trigger with delays between instructions In the smallest case, the data rate is further reduced to about 1kb/s.

Horse Ridge has four radio frequency (RF) channels in the same device and uses frequency multiplexing to control up to 128 qubits. Each RF channel uses direct digital synthesis with 32 digitally controlled oscillators to generate 32 multiplexed qubit frequencies with high precision of 200Hz.

What are Horse Ridge’s key advantages?

Shrinking the form factor (chip and PCB size) required to run quantum systems and reducing the power required.

Ability to scale and control more qubits (up to 128 qubits)

Horse Ridge’s highly flexible pulse control capabilities reduce crosstalk between qubits and improve Improved overall quantum gate fidelity.

The chip can automatically correct for phase shifts (a phenomenon that occurs when the same radio frequency circuit is used to control multiple qubits at different frequencies) and update the digital code after each pulse of the control electronics.

Comparison table

*Contains local oscillator/clock driver, low RF active only

#No mention of included circuitry

?Can be reduced by clock gating

[ISSCC'19] J. C. Bardin et al., “A 28nm Bulk-CMOS 4-to-8GHz <2mW Cryogenic Pulse Modulator

for Scalable Quantum Computing,” ISSCC Digital Technology Research Report, pp. 456-458, 2019.

[RSI’17] C. A. Ryan, B. R. Johnson, D. Ristè, B. Donovan, and T. A. Ohki, “Hardware for dynamic quantum computing,” Rev. Sci. Instrum., 2017.

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