The international research team at POSTECH in South Korea, Raytheon BBN Technologies, Harvard University and the Massachusetts Institute of Technology in the US, the Barcelona Institute of Science and Technology in Spain and the National Institute of Materials Science in Japan have jointly developed ultrasonic sensors. which can theoretically detect microwaves with the highest possible sensitivity. Research findings published in the prestigious international academic journal Nature, are attracting attention as new technologies include quantum computers, to market a generation of new technologies.
Microwaves are used in many scientific and technological fields, including mobile communications, radar, and astronomy. Recently, research has been actively conducted for the detection of microwaves at very high sensitivity for next-generation quantum technologies, such as quantum computing and quantum communication.
Today, microwave power can be detected using a device called a bolometer. A bolometer usually consists of three materials: a material of electromagnetic absorption, a material that converts electromagnetic waves into heat, and a material that converts the heat generated into electrical resistance. The bolometer calculates the number of electromagnetic waves absorbed using changes in electrical resistance. Using semiconductor-based diodes, such as silicon and gallium arsenide in a bolometer, the sensitivity of a state-of-the-art commercial bolometer that operates at room temperature is limited to 1 nanowatt (one billion watts), averaging one second.
The research team exceeded this limit by renovating the material and structure aspect of the device. First, he used the team graphene as a material for absorbing electromagnetic waves. Graphene is composed of a layer of carbon atoms and has a very low electronic heat capacity. The low heat capacity indicates that although it absorbs little energy, it causes a large change in temperature. Microwave photons have very little energy, but if they absorb graphene, they can cause a large rise in temperature. The problem is that the temperature rise of graphene cools very quickly, making it difficult to measure change.
To solve this problem, the research team adopted a device called the Josephson Crossroads. This quantum device, composed of superconducting-graphene-superconducting (SGS), can detect temperature changes in 10 picoseconds (one trillionth of a second) through an electrical process. This makes it possible to detect temperature changes in graphene and the resulting electrical resistance.
By combining these key components, the researchers achieved an equivalent noise power of 1 aW / Hz1 / 2, which means that the device can solve in 1 aW (1 trillion watts) in a second.
“This research is significant because it has established scalable technology to enable next-generation quantum devices,” said POSTECH Professor Gil-Ho Lee, who is leading the research. He explained: “This research has developed the technology of bolometers, which measures how many microwave photons are absorbed per unit of time. But we are currently developing technology to detect a single photon that can separate each microwave photon.” He concluded, “We hope that this technology will maximize the measurement efficiency of quantum computing and drastically reduce indirect resources to enable large-scale quantum computers that will be of great use.” -in those who study the origin of the universe in the field of astronomy and the study of dark matter in particle physics. “He added,” research on basic science is an example of what can be applied in many fields. “
Read The U.S. Army is creating a sensor with 100,000 times greater sensitivity to learn more about this innovation.
Reference: Gilen Ho Lee, Dmitri K. Efetov, Woochan Jung, Leonardo Ranzani, Evan D. Walsh, Thomas A. Ohki, Takashi Taniguchi, Kenji Watanabe, Philip Kim, Dirk Englund and “Graphene-based Josephson joint micrometer bolometer”. Kin Chung Fong, September 30, 2020, Nature.
DOI: 10.1038 / s41586-020-2752-4