Superconducting quantum processor performs well with significantly less wiring

Ingrid Fadelli

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Quantum computers, computing systems that process information using quantum mechanical effects, could outperform classical computers on some computational tasks. These computers rely on qubits, the basic units of quantum information, which can exist in multiple states (0, 1 or both simultaneously), due to quantum effects known as superposition and entanglement.

Many of the quantum computers developed in recent years are based on conventional superconductors, materials that exhibit an electrical resistance of zero at extremely low temperatures. To operate reliably and exhibit superconductivity, circuits based on these materials need to be cooled down to millikelvin temperatures.

In quantum computers, each qubit typically requires its own control line. This means that engineers need to introduce several wires that carry electrical pulses (i.e., signal lines), and the number of necessary wires increases with the number of qubits. As quantum computers grow larger, this can be problematic, as processors become harder to build and reliably operate.

Researchers at Seeqc Inc., a company that develops digital quantum computing systems, recently introduced a new quantum processor that could operate reliably and at millikelvin temperatures, despite requiring significantly less wiring. This processor, introduced in a paper published in Nature Electronics, has a unique design in which qubits and their control electronics are integrated on two separate but connected superconducting chips.

"The development of superconducting quantum computing platforms faces considerable scaling challenges because individual signal lines are required to control each qubit," wrote Caleb Jorda, Jacob Bernhardt and their colleagues in their paper. "This wiring overhead is a result of the low level of integration between the control electronics at room temperature and the qubits operating at millikelvin temperatures. A promising alternative is to use cryogenic superconducting digital control electronics that coexist with qubits."

Overcoming the wiring challenge

To overcome the wiring issues that have so far hindered the development of larger-scale quantum processors, this research team designed a new multi-chip module. This module consists of two separate chips, one hosting qubits and the other control electronics.

The researchers specifically used single-flux quantum control electronics, superconducting digital circuits that generate very short and precise electrical pulses via tiny quantized magnetic signals. The chip hosting these circuits was connected to the chip that contains superconducting circuits using an approach known as flip-chip bonding.

This approach entails placing chips face-to-face and then linking them via microscopic metal bumps. The whole multi-chip module developed by Jorda, Bernhardt and their colleagues operates inside a cryogenic setup that maintains it at millikelvin temperatures.

"We present an active quantum processor unit in which qubits and single-flux quantum control electronics are integrated into a single multi-chip module via flip-chip bonding," wrote the authors. "Our system uses digital demultiplexing to distribute control pulses to several qubits, thus breaking the linear scaling of control lines to the number of qubits. With this approach, we demonstrate single-qubit fidelities above 99% and up to 99.9%."

A new approach to upscale quantum processors

The quantum processor designed by this research team has notable advantages over many other superconducting quantum processors introduced in the past. In initial tests, it was found to perform remarkably well, maintaining excellent control over qubits without the need for extensive wiring.

In the future, the new design could be scaled up to create larger quantum processors that contain many additional qubits and can thus potentially tackle more complex computational problems. In addition, it could inspire the introduction of other similar multi-chip quantum modules that operate reliably and are easier to upscale.

Written for you by our author Ingrid Fadelli, edited by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.

Publication details

Caleb Jordan et al, A quantum computer controlled by superconducting digital electronics at millikelvin temperature, Nature Electronics (2026). DOI: 10.1038/s41928-026-01576-6.

Journal information: Nature Electronics

Key concepts

Quantum algorithms & computationSuperconductivitySuperconductors

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