Highly Efficient Thermal Isolation System for Ultra Low Temperature Operation of Cryoelectric Chips

TO-127 • PT 1.2949 • As of 10/2023
Peter Grünberg Institute
Quantum Information (PGI-11)

Technology

We aim to create an isolator system with appropriate wiring between two cryoelectric chips operating at various temperatures below 10K. The key feature of this invention is the inclusion of a Bragg reflector in the isolator system, which provides thermal isolation and passages for electrical connections. The Bragg reflector induces high phonon scattering perpendicular to its surface, effectively suppressing thermal conduction. This isolator system is placed between the chips requiring isolation, allowing for high-density electrical connections. In our approach, the Bragg reflector may consist of a layered system, resulting in suitable interference and enhanced phonon scattering. Additionally, the layers can be made of materials with different acoustic impedance to further amplify the interference effect and reduce thermal conduction. Another variant involves varying the thickness of the layers to enhance phonon scattering across a wide range of wavelengths, thereby reducing thermal conductivity at cryogenic temperatures.

Problem addressed

Quantum computers, which offer significantly higher computational power than conventional computers, rely on quantum bits (Qubits) that require extremely low temperatures to maintain stability. One problem with controlling or reading out qubits is that no techniques are yet known that enable the necessary thermal insulation while maintaining a high interconnect density at temperatures below -260°C. However, this is a key component for the integration of qubits and cryoelectric circuits. Existing techniques, such as acoustic nanowave devices and porous silicon structures, have limitations in providing the necessary thermal insulation and connection density. So, potential licensees of the new technology may seek an alternative to previous approaches, in order to benefit from improved thermal isolation and improved interconnection density.

Solution

Our new isolator system effectively addresses the thermal limitations of existing systems by significantly reducing heat transfer between chips operating at different temperatures. The Bragg reflector induces high phonon scattering and suppresses thermal conduction. Additionally, the layered structure of the Bragg reflector allows for high-density electrical connections, enabling efficient information exchange between the isolated chips. The use of superconducting electrical connections further minimises heat generation and thermal influence on the system. Moreover, the inclusion of solid materials with superfluid helium channels or high thermal conductivity enhances heat dissipation, maximizing the isolating effect of the system. A cascaded arrangement of Bragg reflectors enables isolation even with larger temperature differences, further reducing heat exchange. Overall, this technology offers improved thermal isolation, efficient electrical connections, and enhanced heat dissipation.

Benefits and Potential Use

Our isolator system is particularly designed for application in quantum computers. By providing effective thermal isolation between the control and readout circuitry (operating at higher temperatures) and the qubit chips (operating at extremely low temperatures), it ensures stable and controllable qubit states. The superconducting electrical connections within the isolator system enable high-density signal exchange between the chips, crucial for quantum computing operations. Additionally, the technology's versatility allows for various applications beyond quantum computing. It can be employed in any applications requiring significant thermal isolation and high-density electrical connections between chips operating at various temperatures, such as advanced electronic devices, superconducting circuits, and cryogenic sensors. The ability to bridge significant temperature differences and minimize heat exchange makes this technology highly attractive for licensing, offering improved performance and reliability.

Development Status and Next Steps

Forschungszentrum Jülich has extensive expertise in this field and holds several patents. The technology described above has already been initially verified through prototypes and is continuously being developed further. The Peter Grünberg Institute (PGI-11/JARA-IQI) – Quantum Information – already cooperates with numerous national and international companies and scientific partners. Forschungszentrum Jülich focuses on energy and cost-efficient devices, suitable for various emerging technologies. We are continuously seeking for cooperation partners and/or licensees in this and adjacent areas of research and applications.

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