Quantum electronics differs significantly from conventional electronics. In traditional systems, memory is stored in binary numbers. In contrast, quantum electronics uses qubits for storage, which can take many forms, including electrons trapped in nanostructures known as quantum dots. However, the ability to transmit information beyond the boundaries of a neighboring quantum dot is a significant challenge and therefore limits the design possibilities of qubits.

Now in a recently published study Physical Examination LettersResearchers from the Institute of Industrial Sciences at the University of Tokyo are solving this problem: They have developed a new technology for transmitting quantum information over distances of tens to hundreds of micrometers. This advance could increase the functionality of future quantum electronics.

transmission mechanism

How can researchers transfer quantum information from one quantum dot to another on the same quantum computer chip? One way would be to convert electronic (matter) information into light (electromagnetic wave) information: by producing light-matter hybrid states. Previous work was not compatible with the single-electron requirements of quantum information processing. The goal of the research team’s research was to improve high-speed quantum information transfer through more flexible design and compatibility with existing semiconductor fabrication tools.

“In our work, we connect several electrons in the quantum dot to an electrical circuit known as a terahertz split-ring resonator,” explains Kazuyuki Kuroyama, lead author of the study. “The design is simple and suitable for large-scale integration.”

Previous work relied on coupling a resonator to a group of thousands to tens of thousands of electrons. In fact, the connection strength depends on the size of this community. In contrast, the current system confines only a few electrons, which is suitable for quantum information processing. But both electrons and terahertz electromagnetic waves are confined to an extremely small area. The strength of the coupling is therefore comparable to multi-electron systems.

“We are excited because we are using structures common in advanced nanotechnology and often integrated into semiconductor fabrication to help solve the practical problem of quantum information transfer,” says senior author Kazuhiko Hirakawa. “We also look forward to applying our findings to understanding the fundamental physics of light electron-bound states.”

This work is a significant step forward in solving the previously problematic problem of quantum information transfer, which has had limited application in laboratory results. In addition, this light-matter conversion is considered one of the main architectures of large-scale quantum computers based on semiconductor quantum dots. Because the researchers’ results are based on materials and procedures common in semiconductor manufacturing, practical implementation should be simple.