Diamonds are often prized for their flawless brilliance, but St. Chong Zu, a professor of arts and sciences at Washington University in St. Louis, sees greater value in these natural crystals. As reported Physical Examination LettersZu and his team have taken an important step in their quest to turn diamonds into a quantum simulator.

Co-authors of the paper include Kater Murch, Charles M. Hochenberg Professor of Physics and Ph.D. students Guanghui He, Ruotian (Reginald) Gong and Zhongyuan Liu. His work is supported in part by the Center for Quantum Leaps, a landmark Arts and Sciences strategic plan initiative that aims to apply quantum ideas and technologies to physics, biomedicine and life sciences, drug discovery, and other wide-ranging fields.

Researchers transformed diamonds by bombarding them with nitrogen atoms. Some of these nitrogen atoms replace carbon atoms, creating defects in a perfect crystal. The resulting gaps are filled with electrons with their own spin and magnetism, quantum properties that can be measured and manipulated for a wide variety of applications.

As Zu and his team previously discovered in their boron research, such defects could potentially be used as quantum sensors that respond to their environment and each other. In the new study, researchers focused on another possibility: using imperfect crystals to study the incredibly complex quantum world.

Classical computers (including state-of-the-art supercomputers), even those containing only a dozen or so quantum particles, are inadequate for simulating quantum systems. This is because the dimensions of quantum space grow exponentially with each particle added. But a new study shows that it is possible to directly model complex quantum dynamics using a controlled quantum system.

“We carefully design our quantum system to create a simulation program and make it work,” Zu said. “At the end of the day, we monitor the results. This is something that is almost impossible to solve with a classical computer.”

The team’s progress in this area will enable the exploration of some of the most exciting aspects of many-body quantum physics, including the realization of new phases of matter and the prediction of events occurring in complex quantum systems.

In the latest study, Zu and his team were able to keep their system stable for up to 10 milliseconds, which is a long time in the quantum world. Notably, unlike other quantum simulation systems that operate at ultra-low temperatures, their diamond-based system operates at room temperature.

One of the keys to preserving a quantum system is to prevent thermalization, the point at which the system absorbs so much energy that any defects lose their unique quantum properties and end up looking the same. The team found that they could delay this outcome by running the system so fast that it didn’t have time to absorb the energy. This leaves the system in a relatively stable “preheat” state.

The new diamond system allows physicists to study the interactions of several quantum fields simultaneously. This also opens up the possibility of more sensitive quantum sensors. “The longer a quantum system lives, the greater the sensitivity,” Zu said.

Zu and his team are currently collaborating with other WashU scientists at the Quantum Leap Center to gain new knowledge across disciplines. Zu is collaborating with associate professor of physics Eric Henriksen in the Department of Arts and Sciences to improve sensor performance. He also plans to use these sensors to better understand quantum materials created in associate professor of physics Sheng Ran’s lab.

He is also collaborating with Philip Skemer, professor of Earth, Environmental and Planetary Sciences, to obtain atomic-level representations of magnetic fields in rock samples; and with physics professor Shankar Mukherjee to map thermodynamics in living biological cells.