Mr. Eugene Profis reports

QUANTUMCORE BEGINS DEVELOPMENT OF FOURTH CRITICAL TECHNOLOGY: CHIP-SCALE MAGNETLESS CIRCULATORS FOR SCALABLE QUANTUM COMPUTING

Quantumcore Ltd. has begun the development a fourth critical technology for its quantum computing infrastructure platform: chip-scale magnetless cryogenic circulators, designed to replace the bulky magnetic circulators currently used in superconducting quantum computers.

The development program represents another step in Quantumcore's strategy to build essential infrastructure technologies positioned between quantum control electronics and quantum processing units (QPUs). The company believes miniaturized, non-magnetic circulators could become an important enabling technology as superconducting quantum computers scale.

The new technology will be developed under Quantumcore's sponsored research agreement with the University of Waterloo, led by Prof. Raafat Mansour of the Department of Electrical and Computer Engineering. The program will build upon the company's recently announced cryogenic phase-change material (PCM)/superconducting multiplexing microchip initiative, with the objective of developing complementary technologies that can ultimately operate together within an increasingly integrated superconducting infrastructure stack.

Solving the circulator size bottleneck

Superconducting quantum computers rely on extremely weak microwave signals to measure the state of quantum bits or qubits. Circulators are essential components of the readout chain, directing microwave signals along designated paths while helping isolate sensitive quantum processors from unwanted noise and reflections generated by downstream electronics.

Conventional cryogenic circulators generally use ferrite materials and permanent magnets to achieve non-reciprocal signal transmission. While these components are widely used and provide important performance characteristics, their physical size and magnetic assemblies create increasing integration challenges as quantum processors scale.

Unlike microchips, traditional circulators are relatively large, discrete microwave components that must be physically installed, connected and thermally anchored within the cryostat.

As superconducting systems move toward thousands of readout channels, the cumulative volume occupied by circulators, their connectors and associated microwave cabling could become a significant obstacle to scaling.

Quantumcore believes replacing conventional magnetic circulators with compact, chip-scale non-magnetic devices will substantially reduce the physical footprint of the superconducting readout infrastructure, potentially enabling higher-density signal routing and more efficient use of valuable cryogenic space.

For example, a typical commercially available cryogenic circulator working in the four-to-eight-gigahertz (GHz) frequency range measures approximately 22 by 25 by 10 millimetres, excluding connectors. These components provide excellent microwave performance but occupy substantially more space than an integrated circuit. A chip-scale replacement could potentially consolidate multiple functions within a much smaller package, reducing mounting hardware, connector requirements and the overall volume of the readout assembly.

The potential benefits become increasingly significant when multiplied across thousands of readout channels.

"Today's quantum computers rely on circulators that are measured in centimetres, while the semiconductor industry routinely manufactures complex circuits measured in millimetres," said Eugene Profis, chief executive officer of Quantumcore. "As superconducting quantum computers scale toward one million qubits, the physical space occupied by thousands of discrete microwave components becomes a major engineering challenge. Our objective is to move this critical functionality onto compact, non-magnetic chips that can be integrated with our multiplexing technology, helping the industry build much larger quantum computers without proportionally increasing the size and complexity of the cryogenic infrastructure."

Developing a chip-scale magnetless circulator

Quantumcore's research program will investigate magnetless circulators based on RF switching and time-varying circuit techniques that eliminate the need for conventional ferrite materials and permanent magnets.

In these architectures, switches are controlled using precisely timed electrical signals to create directional microwave transmission. This approach, known as spatiotemporal modulation, can allow signals to travel preferentially in one direction without requiring magnetic bias.

The company believes its PCM/Superconducting switching development program offers a complementary technology foundation for this work. Low-loss, broadband switches could potentially enable compact circulators with the performance characteristics required for superconducting quantum computing.

The approach also offers an opportunity to address another important limitation of conventional ferrite circulators: the presence of magnetic materials near highly sensitive superconducting circuits.

By eliminating permanent magnets, Quantumcore aims to develop components that are easier to integrate into densely packed cryogenic systems while reducing potential magnetic interference.

Quantumcore's objective is to translate this class of technology into commercially manufacturable cryogenic hardware. Key development priorities will include insertion loss, isolation, operating bandwidth, cryogenic power consumption, compatibility with superconducting circuits and scalable fabrication.

Integration with Quantumcore's PCM/superconducting multiplexing microchips

An important element of Quantumcore's strategy is the potential integration of magnetless circulators with the company's recently announced PCM/Superconducting multiplexing microchips.

The two technologies address different but complementary challenges within the superconducting quantum computing stack.

PCM/superconducting multiplexing microchips are being developed to reduce the number of physical signal connections required between room-temperature controllers and the QPU, allowing multiple qubits or readout channels to share portions of the control and readout infrastructure.

Magnetless circulators are being developed to miniaturize the directional signal-routing and isolation components used within the cryogenic microwave readout chain.

Together, these technologies could enable more highly integrated cryogenic modules that combine signal switching, routing and isolation while reducing reliance on bulky discrete microwave components and associated cabling.

Quantumcore believes this approach could become increasingly important as the industry works toward superconducting processors containing hundreds of thousands or one million physical qubits.

The company intends to explore opportunities to work with large interconnect, semiconductor packaging and cryogenic systems companies to integrate these technologies into future quantum computing architectures.

World-class RF and cryogenic engineering expertise

Prof. Mansour is one of Canada's leading experts in microwave engineering and radio-frequency (RF) integrated circuits, with significant previous work focused on advanced switching technologies and the development of superconducting and cryogenic RF devices. He is a professor in the Department of Electrical and Computer Engineering at the University of Waterloo, a former Tier 1 Canada research chair in micro-nano integrated rf systems, and served two consecutive terms as the NSERC industrial research chair in RF technologies.

Prof. Mansour has an exceptional record of translating university research into commercial technologies. Technologies developed in his research laboratory have contributed to the co-founding of Canadian technology companies, including AdHawk Microsystems and Integrated Circuit Scanning Probe Instruments (ICSPI Corp.). Throughout his distinguished career, Prof. Mansour has been awarded 41 Canadian and U.S. patents and written more than 475 peer-reviewed technical publications. His expertise in advanced RF systems, integrated circuit design, cryogenic superconducting technologies and technology commercialization is expected to support Quantumcore's development of scalable magnetless circulators.

Prof. Mansour's laboratory has previously developed other types of advanced PCM/superconducting switches, providing an established switching-technology foundation for the broader cryogenic development program. He is also currently working on a multiplexing device that Quantumcore intends to advance and optimize for superconducting quantum computing applications.

The collaboration will combine Prof. Mansour's internationally recognized technical expertise with Quantumcore's commercialization strategy focused on supplying critical infrastructure technologies to the global quantum computing industry.

Building a four-technology quantum infrastructure platform

Quantumcore believes magnetless circulators represent its fourth critical technology platform, complementing three existing development initiatives:

• Superconducting second-stage KI-TWPA amplifiers: designed to operate at approximately four Kelvin and potentially replace conventional semiconductor HEMT amplifiers in superconducting quantum computing readout systems, reducing heat generation while providing low-noise microwave amplification;
• Single-photon detectors: advanced photon-detection technologies targeting quantum computing, quantum networking, quantum communications and other applications requiring high performance optical detection;
• Cryogenic PCM/superconducting multiplexing microchips: designed to reduce the physical wiring and interconnect requirements associated with scaling superconducting quantum processors;
• Chip-scale magnetless circulators: designed to replace bulky ferrite-based microwave circulators with compact, non-magnetic integrated devices for signal routing and isolation.

The company believes these technologies position Quantumcore to address several of the most important infrastructure bottlenecks in next-generation quantum computing systems.

"Our strategy is to build the critical hardware infrastructure that allows quantum computer manufacturers to scale," added Mr. Profis. "We are developing superconducting amplifiers to address heat and signal amplification, PCM/superconducting multiplexing to address wiring complexity, and now magnetless circulators to address the size and integration limitations of conventional microwave components. We believe these technologies can ultimately work together as part of a highly integrated cryogenic infrastructure platform."

Research funding and commercialization strategy

The magnetless circulator development program forms part of Quantumcore's sponsored research agreement with the University of Waterloo, entitled "Cryogenic Multiplexing and Magnetless Circulators for Quantum Computer Applications."

Under the agreement, Quantumcore will contribute capital and resources toward the combined research program. In addition to the company's direct financial contribution, Quantumcore intends to apply for supplemental non-dilutive funding through applicable federal and provincial grant programs to support and potentially accelerate development activities.

The associated intellectual property agreement provides Quantumcore with a fully paid-up, royalty-free, irrevocable and exclusive licence to use and commercially exploit university research results within cryogenic applications and associated cryogenic fields, including the ability to grant sublicences within that field.

Quantumcore intends to evaluate commercialization opportunities for its magnetless circulator technology alongside its PCM/superconducting multiplexing program, with the longer-term objective of producing integrated, scalable and commercially manufacturable hardware for superconducting quantum computer manufacturers.

About Quantumcore Ltd.

Quantumcore is a Canadian quantum infrastructure company developing critical hardware technologies positioned between quantum control systems and quantum processing units. The company's technology portfolio includes superconducting quantum amplifiers, cryogenic PCM/superconducting multiplexing microchips, magnetless circulators and advanced single-photon detectors. Quantumcore is focused on addressing the signal amplification, heat generation, wiring complexity, component miniaturization and photon-detection challenges associated with scaling quantum computing systems toward commercially viable, fault-tolerant architectures.

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