Intel & QuTech outline 'milestone' in quantum computing

Intel and Qutech have published details of 'Horse Ridge' – the partners' first cryogenic quantum computing control chip, which could pave the way for further understanding how quantum practicality could solve real-world problems.

The partners recently presented a research paper at the San Francisco 2020 International Solid-State Circuits Conference (ISSCC).

The paper outlines how Horse Ridge can address challenges associated with developing a quantum system that can achieve quantum practicality. Quantum practicality means demonstrable results in the areas of fidelity, flexibility, and scalability.

"Today, quantum researchers work with just a small number of qubits, using smaller, custom-designed systems surrounded by complex control and interconnect mechanisms. Intel's Horse Ridge greatly minimises 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," says Intel Labs director of quantum hardware, Jim Clarke.

Intel explains further:

Flexibility – Horse Ridge can cover a wide frequency range, which means it can control superconducting qubits (known as transmons) and spin qubits. Transmons typically operate around 6 to7GHz, while spin qubits operate around 13 to 20GHz.
Intel is currently researching silicon spin qubits. These could potentially operate at temperatures up to 1 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.

Fidelity – an increase in cubit count could lead to decreased qubit fidelity and performance.

The partners say that they developed Horse Ridge to optimise multiplexing technology that allows the system to reduce errors from 'phase shift', which is when qubits experience crosstalk as a result of a quantum system that controls many qubits at different frequencies.

"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," the partners explain.

Scalability – The partners chose an integrated SoC design that uses Intel's 22nm FFL (FinFET Low Power) CMOS technology and integrates four radiofrequency channels into a device.

"Each channel can 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," the partners explain.

"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.

Intel and QuTech explain that Horse Ridge provides a way of simplifying complex control electronics that are required to operate a quantum system that can achieve quantum practicality.

QuTech is a partnership between TU Delft and TNO – Netherlands Organisation for Applied Scientific Research.