Scientists have found an unexpected link between very different areas of quantum physics. As members of the NIST Center for Quantum Networks, they experimentally observed a new three-dimensional quantum phase of matter showing anomalous symmetry at finite temperatures. Senior author Tyler D. Ellison and his team have made a noteworthy discovery that challenges the historical idea of realizing phases of quantum matter in lower dimensions. This unanticipated finding lays the groundwork for the future experimental and theoretical work necessary to advance this exciting field.
For decades, scientists thought that quantum phases of matter were impossible in two dimensions. They assumed this restriction extended into three dimensional space. This new study turns that assumption on its head. It reveals a theoretical template for a 3D system that displays a rare two-form symmetry at temperatures above absolute zero. The team’s investigation leads to exciting new opportunities for us to explore how we might put these findings to use in practical, real-world quantum systems.
Background on Quantum Phases of Matter
Scientists categorize quantum phases of matter based on their characteristic signatures. Among those different kinds of orders, one of the most stunning is topological order. An example of this is topological order, which exhibits long-range entanglement between groups of particles over the whole system. This topological entanglement leads to a ground state degeneracy which is sensitive to the global shape of the system itself. Importantly, topological order is unique in its flaunted robustness to local perturbations. This unique feature has made it an attractive field of study for scientists looking to explore and control quantum systems.
Conventionally, topological phases were expected to only be found at absolute zero temperature. In organic crystals, thermal fluctuations typically wash out these phases. As Ellison and his colleagues have now found, there are conditions in which these phases can survive at warmer temperatures. Their research shows how some quantum systems can remain coherent even with the noise of a thermal bath.
“It has long been appreciated that symmetries play an important role in characterizing phases of matter,” – Tyler D. Ellison
This claim highlights the fundamental importance of symmetry to our understanding of all states of matter. In their research, Ellison and his team used some new theoretical tools. Through their work, they investigated how these anomalous symmetries can expose intricate entanglement structures in many-body quantum systems.
Implications of the Research
Scientists have found a novel quantum phase of matter that persists even at finite temperatures. This unexpected clear finding contradicts current theories and raises new questions about how this recommendation process might be used. As Ellison explains, the context of this research is important. He says that it sets the stage for engineers to synthesize exotic quantum states in tunable experimental platforms.
“In the last several years, we have made substantial progress in our ability to control [quantum systems]—over a range of different platforms: [superconducting qubits], trapped ions, [neutral atoms], photonics, and so on,” – Tyler D. Ellison
For all of the technological developments around AI, Ellison concedes that the challenge is a bit built in, with hardware limitations and environmental noise coming into play. These factors can induce non-ideal operations in quantum systems, making it difficult to realize these new phases in practice.
The research team will continue to explore this newly revealed phase of matter. They seek to develop simple diagnostics to see whether or not they’ve managed to get through this phase successfully. If they are successful, they will be able to explore further into its more exotic properties.
“Another important direction is for us to develop simple diagnostics to detect whether we have successfully prepared the phase of matter. Once we have an experimental realization, it opens the door to exploring the exotic properties of quantum phases of matter at non-zero temperatures,” – Tyler D. Ellison
Moving Forward with Research
Ellison and his coauthors didn’t set out to find new quantum phases in three dimensions. They had started their project with something else in mind. These results were surprising but quite promising, causing them to reconsider long-held assumptions about dimensionality in quantum physics.
“It came as a complete surprise to us that there exists a quantum phase of matter in three dimensions at non-zero temperature,” – Tyler D. Ellison
The researchers concede that convincing reasons long indicated that such quantum phases were impossible in three dimensions. Their paper demonstrates that such four-dimensional quantum phases can be realized at finite (nonzero) temperatures. Yet, this finding is theoretical rather than practical at this point.
“There are strong arguments to say that no such quantum phases of matter exist in 2D, and prior to our work, the general expectation in the community was that the arguments hold in 3D,” – Tyler D. Ellison
Ellison’s team is engaging strategically and deeply in this new chapter. Ultimately, they hope to use their empirical findings as guides for designing quantum systems that can achieve higher performance at equilibrium. Now, researchers are exploring the intersection of anomalous symmetry and temperature. As with any scientific frontier, the quantum revolution holds tremendous promise to increase our knowledge and mastery of quantum mechanics.