Article Author: Maurizio Di Paolo Emilio
Cryogenic cables could be the key to simplifying quantum computer design.
Delft Circuits announced its inclusion in the Antarctic BICEP project supporting NASA’s Jet Propulsion Laboratory (JPL) and other project partners at the California Institute of Technology. As part of the new camera, the JPL team decided to install an advanced cable made by Delft Circuits into the telescope’s cryostat.
The JPL team will also replace the telescope’s sensor with a new Thermal Motion Inductance Detector (TKID), a superconducting detector that exploits the properties of quantum mechanics. The infrastructure requirements are very similar to those required to set up and measure qubits in quantum systems.
In recent years, we have witnessed a growing interest in quantum computing from large multinational groups, researchers and startups. Current supercomputers, also known as high-performance computing (HPC) systems, are computationally powerful, but cannot yet solve problems that exceed a certain level of complexity.
Quantum computing approaches, on the other hand, promise to overcome current HPC limitations by leveraging computing power that grows higher as systems use more qubits.
Quantum Computer Design Challenge
Creating a quantum computer involves unprecedented design challenges because individual qubits must be kept as stable as possible and unalterable by external agents. Depending on the type of technology used to implement the qubits, it is often necessary to generate temperatures close to absolute zero to reduce noise as much as possible. As a result, quantum computing hardware is typically placed inside cryogenic dilution refrigerators.
The challenge then is to connect control electronics that typically operate at room temperature with low-temperature quantum devices. Considering that next-generation quantum processors can integrate more than a thousand qubits, this process requires very complex wiring.
Figure 1 below shows the details of a quantum computer and highlights some of the complex wiring involved in designing a quantum computer. Normal coaxial cables may be sufficient to process and read dozens of qubits (with a non-negligible burden), but require higher density interconnects, both from a physical dimension standpoint and the need to reduce conduction heat internally. dilution refrigerator.
Solutions from Delft Circuits
Founded in 2017 and headquartered in Delft, the Netherlands, Delft Circuits has developed a revolutionary quantum computer cable technology called Cri/oFlex. Initially created as part of university research to solve connectivity problems in quantum computer prototypes, the technology aims to create seamless wiring for quantum computing. The result is a flexible microwave cable with the following characteristics:
- Shrinking form factor and scalability as the number of qubits increases
- Low thermal conductivity (< 4μW @ 3K – 0.7K thermal load per channel)
- ease of installation
- Integrated signal attenuation and filtering
- high durability
Cri/oFlex combines flexible cryogenic cables with standard RF connectors to create interconnect solutions offering both single and multi-channel cables.
“We want to be the best supplier of quantum hardware for a specific part of the value chain in the quantum industry,” said Sal Jua Bosman, CEO and co-founder of Delft Circuits, and Artem Nikitin, Sales Director of Delft Circuits. Interview with EE Times. “We focus primarily on input/output systems, which have a wide range of applications from sensors to computers to biomedical sensing.”
The cable shown in Figure 2 is made using a unique combination of polyimide and silver, resulting in a very thin stripline channel with high microwave performance and flexibility.
“What we are making is flexible microwave and cryogenic cabling. A cable with all these properties in one shot has never been made before,” said Nikitin and Bosman.
“You can always use microwave cables, but you can use rigid or flexible cables, but these are for DC signals,” says Bosman. And cryogenics are above that.”
Additionally, these cables overcome traditional microwave engineering challenges at cryogenic temperatures by incorporating all filtering components (low-pass filter, band-pass filter, and attenuator). By integrating all necessary components, you can reduce potential points of failure and installation time and increase the robustness of your setup.
Delft Circuits offers three product lines based on the same technology but with different specifications and performance. These products address many types of applications such as quantum computing, astrophysics, optics, metrology, and more.
These highly flexible microwave I/O cables meet the needs of scanning probe microscopes and other vibration-sensitive instruments. These cryogenic RF cables are extremely thin and flexible, allowing signal transmission with minimal vibration coupling. As such, the Cri/oFlex 1 series features a 0.3mm thin microwave transmission line and a narrow width of 1mm.
This single-channel microwave I/O cable is ideal for dense sample spaces in refrigerators. They are small in size and can reduce the heat load, increasing the number of microwave lines in a cryostat. Flexible RF cabling is based on monolithic waveguides and its phase stability is virtually insensitive to vibration or bending. Cri/oFlex technology is highly flexible from room temperature to cryogenic temperatures.
The Cri/oFlex 3 series is the company’s flagship product designed specifically for expandability. Using signal lines with distributed attenuation and integrated microwave signal conditioning, few additional microwave components are required.
Because of its small volume and low thermal load, the Cri/oFlex 3 supports a large number of signal lines that can be installed inside a dilution refrigerator. The flexible cable contains up to 8 parallel channels with 1mm pitch between channels and no microwave breakout between stages.
Cri/oFlex use cases
Many Delft Circuits customers microwave at low temperatures. Among these customers is NASA’s JPL, whose research team uses astrophysical detectors to measure microwave background radiation from space.
“To detect this radiation, we need a sensitive microwave motion inductance detector (MKID) and use a cable solution to read the signal,” Nikitin and Bosman said.
MKID devices provide a high level of multiplexing in combination with microwave frequency resonators. Thus, up to 1,000 detector pixels can be read using a single MKID cable and microwave transmission measurements. To enable high-resolution imaging, these detector arrays are currently scaling to tens of thousands of pixels.
Because these detector chips are typically mounted on the bottom of the telescope, they require a specially built cryostat with limited space and cooling capacity. Given the current trend to expand these detector arrays, MKID microwave cabling is needed that is compact, simple to install and has a low thermal load.
“A third of total revenue comes from quantum computing,” Nikitin and Bosman said. “Quantum computing is our first beachhead, but we are thinking about other applications for our product, such as space applications, STM and AFM, and astrophysics very close to biomedical imaging.”
This article was originally posted EE Times.
Mauricio di Paolo Emilio I have a PhD. Graduated in Physics and is a telecommunications engineer. He has been involved in various international projects in the field of gravitational wave research, designing space technologies for thermal compensation systems, X-ray microbeams, communications and motor control. Since 2007 he is a technology writer specializing in electronics and technology, collaborating with several Italian and English blogs and magazines. From 2015 to 2018 he served as Editor-in-Chief of Firmware and Elettronica Open Source. Maurizio enjoys writing and talking about Power Electronics, Wide Bandgap Semiconductors, Automotive, IoT, Digital, Energy and Quantum. Maurizio is currently Editor-in-Chief of Power Electronics News and EEWeb, and European Correspondent for EE Times. He is the host of PowerUP, a podcast about power electronics. He has contributed to several technical and scientific articles as well as several Springer books on energy harvesting, data acquisition and control systems.