Milestone: open source room temperature control system for superconducting quantum processor
The team of physicists and engineers at Lawrence Berkeley Lab successfully proved the feasibility of a low-cost, high-performance radio frequency (RF) module for quantum bit control at room temperature. They built a series of compact RF modules to mix signals to improve the reliability of the superconducting quantum processor control system. Their tests show that the use of modular design method can reduce the cost and size of traditional RF control system, and still provide a performance level better than or equivalent to that of commercial system.
Their research was published in the review of scientific instruments [1] of the American Federation of Physics (AIP), and was featured by AIP Science [2]. Their research is open source and has been adopted by other quantum information science (QIS) teams. The team expects that the compact design of RF module is also applicable to other qubit technologies. The research was conducted at the advanced quantum test bench (AQT) of Berkeley Laboratory and funded by the science office of the U.S. Department of energy.
Although significant progress has been made in building processors with more qubits (the ultimate need to prove that quantum computers are superior to classical computers), quantum computers still have the problems of noise and error prone. Each additional qubit brings new complexity and the possibility of electrical failure, especially at room temperature. The growth of complexity and computing power requires rethinking some core control elements.
Traditional RF control systems use analog circuits to control superconducting qubits, but it will become huge and extremely complex, which will become a potential fault point and increase the cost of hardware control. Gang Huang and Yilun Xu, AQT researchers from the accelerator technology and Applied Physics Department (atap) of Berkeley Laboratory, demonstrated a new method of controlling qubits, which has provided enhancements to other quantum computing projects in the user program of the test-bed. The team replaced the larger and more expensive traditional RF control system built for Berkeley Laboratory, which uses smaller interactive hybrid modules.
Left: AQT low temperature dilution refrigerator. Right: two RF mixing modules: up converter and down converter.
A key aspect of this modular system is to provide high-resolution, low-noise RF signals required to manipulate and measure superconducting qubits at room temperature. Therefore, it is very important to convert qubit operation and measure signal frequency between electronic baseband and quantum system.
Huang explained: "the new module shows low noise and high reliability operation, and is now becoming our laboratory standard for microwave frequency modulation / demodulation in many different experimental configurations of AQT."
RF hybrid module for electronic control of superconducting quantum processor.
Using the team's low-noise RF mixing module to convert the bandwidth between the electronic baseband and and the inherent frequency band of the quantum system with limited if, researchers can use the converter with less noise to obtain better performance at lower cost.
Huang and Xu said that although their system is designed for superconducting systems, it can be extended to other quantum information science platforms. "Generally speaking, the architecture of RF mixing can be extended to higher frequencies. Therefore, if we replace some electronic components with appropriate frequencies, this compact design should be able to adapt to other qubit platforms, such as semiconductor qubit systems."
The researchers also designed electromagnetic interference shielding to eliminate unnecessary interference, which will reduce signal integrity and limit overall performance. This shielding is designed to prevent the common problems of quantum computers - signal leakage and interference with surrounding electronic devices.
With the release of the open source control system, the team hopes to be used by the wider community and contribute to the repository to improve the hardware. By replacing some electronic components with appropriate frequencies, this compact design can adapt to various quantum computing facilities.
"This is one of our first efforts to develop an open source control system for superconducting quantum processors. We will continue to optimize the physical size and cost of the module and further integrate with our FPGA based controller to improve the scalability of the qubit control system," Huang explained.
Looking to the future, researchers have been trying to create new possibilities of quantum computing and provide new technologies to control quantum bits.
"This integration and optimization will help room temperature based control systems keep up with the complexity of quantum processors," Xu said.
Link:
[1]https://aip.scitation.org/doi/10.1063/5.0055906
[2]https://aip.scitation.org/doi/10.1063/10.0005687
