Extraction of valuable insights from diamonds MIT news

If Changhao Li wanted to trace the origins of his love for nature, he would point to a time when he was 9 years old watching the night sky from his childhood home in the small town of Jinan, China. “At the time, I felt that nature was so beautiful, I just wanted to go outside the Earth, go to the Moon or even Mars,” Li recalls.

This childhood dream gave birth to his love for physics, which he pursued in high school and high school, and eventually at Xi’an Jiaotong University in China.

Li’s passion for heaven has since taken on a more earthly and microscopic form: it has evolved into a love of quantum physics. Li is a fifth-year doctoral student in the Department of Nuclear Science and Engineering (NSE) and is working with a professor to study the science of quantum information, including quantum sensing and computation. Paola Cappellaro.

Quantum leaps

The main thesis of quantum information science is that changing the state of a substance at the subatomic level can have significant effects on a much larger scale. For example, quantum computation depends on the smallest changes in the properties of materials to store and process more information than a simple classical binary mode could use.

The basic unit of information in quantum computing that equates to a bit in classical computers is called a qubit. One way to produce these qubits is to exploit defects in the structures of the materials.

The Li aspect of the study is dedicated to defects in very small diamonds, some of which are on the nanometer scale. Experiments involve the introduction of an atomic-scale defect in these diamonds, known as nitrogen vacancy centers, and very small defects, using microwaves or lasers to create and control quantum states.

One of Li’s projects measures the fluorescence emitted by a disturbed diamond to obtain more information about an external stimulus. Just as you measure the temperature of an oven to see how hot it is, by measuring the fluorescence emitted by such a defective diamond, you can find out how it feels and how much. For example, a sensor capable of detecting as many as several hundred filaments of the SARS-CoV-2 virus that causes Covid-19 is one of the programs Li is researching with his colleagues.

To Physical Review LettersLi has published the findings of another research project evaluating the symmetry of quantum systems. To study the properties of quantum systems, we need to understand how quantum states behave over time, and their symmetry is important. “Creating a system of desired symmetry is an insignificant task,” says Li. “Quantum properties are very unstable because they can interact with the environment. We need a very good time to use our qubits, and here we have developed a method to manage and describe such a system. Another object of research, the findings of which will be published shortly, is to model the tensor field using diamond defects related to fundamental science.

Li says that understanding quantum information is primarily about studying basic sciences. “The basic principles of this world are beautiful and can explain many interesting phenomena,” he emphasizes. “It allows me to explore the universe, to understand how nature works,” Li adds.

A person who travels far knows more

The passion for understanding how nature works, whether on a scale of stars or a small quantum unit, has piqued Li’s interest in physics since childhood.

His parents encouraged him to love physics, and the high school teacher taught him to think critically, notice mistakes in textbooks, and not swallow information as the truth. “You need to do simple experiments to find the truth for yourself,” Li took a lesson from high school.

When this lesson was safely postponed, Li realized the high school was a little more complicated and was initially aimed at nearly 1,000 middle school students. However, hard work and learning from others led him to the top.

After graduating from high school in high school, Li continued to study physics at Xi’an Jiaotong University, about 600 miles west of Beijing. This was the first time he had left home, and he noticed that his learning needed to be encouraged on topics such as linear algebra. Again, the hard work paid off and Li finished high in her class.

The university gave Li the opportunity to study in the United States as part of his second-year and junior college courses. Through exchange programs, in 2015 Li attended the University of Notre Dame, where he conducted research for two months in the summer, and in 2016. – University of California, Berkeley. The trip reinforced one of Li’s favorite quotes: “A person who travels far knows more.”

Our Lady’s Cathedral Li was abroad for the first time – he remembers trying to get used to burgers and fries, a radical departure from the traditional Chinese food he loves.

It was research at Berkeley – he fondly remembers the university library and dining rooms – that strengthened his love of quantum physics. When he returned to China, he knew he wanted to attend a graduate school and continue his research in the field. MIT has lured NSE as an opportunity to “work with the most amazing people in the world,” says Li. Cappellaro is his inspiration – “it has taught me to think about research, I am very grateful,” he says.

In his spare time, Li re-learns Chinese cuisine – his parents help with advice – and plays mobile games such as Arena of Valor with friends. Learning to play the guitar was his pandemic hobby.

His core love of nature and learning how things work continues to inspire Li. “I focus on the smallest things and there’s something really amazing out there. It’s also about nature, right? If you know how this little thing works, you might as well learn how the bigger things work, ”says Li.

Godfrey Kemp

"Bacon fanatic. Social media enthusiast. Music practitioner. Internet scholar. Incurable travel advocate. Wannabe web junkie. Coffeeaholic. Alcohol fanatic."

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