This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Many complex quantum systems rapidly lose the recognizable patterns of their initial states as their components interact. To describe patterns of regular and chaotic motion in specific systems, physicists can construct a mathematical map called an effective phase space.
In some classical systems that follow familiar laws of motion, orderly and chaotic paths occupy different regions of phase space. Yet establishing whether a comparable pattern exists in quantum many-body systems (i.e., systems with many interacting quantum components) has so far proved challenging, partly because interactions in these systems can produce a quantum phenomenon called entanglement. When parts of a system are entangled, their combined quantum state cannot be fully described by treating each independently.
Researchers at Zhejiang University and the University of Leeds have devised a new approach to search for recurring patterns of activity in complex, chaotic quantum many-body systems. This approach, outlined in a paper published in Nature Physics, was successfully used to identify a stable recurring pattern in a quantum processor with multiple interacting qubits. "This work grew out of our long-standing collaboration with Zhejiang University on using quantum processors to understand what happens when many quantum particles interact and evolve together," Zlatko Papić, senior author of the paper, told Phys.org.
"Normally, such systems rapidly lose memory of how they started. Understanding when and how they resist this fate is one of the difficult questions we have been exploring." This recent study builds on earlier research by Papić and his collaborators at Zhejiang University and the University of Leeds. In their earlier work, the team showed that some starting states in a 30-qubit superconducting processor could repeatedly return to a recognizable pattern, instead of settling into the disordered behavior typically associated with complex interacting quantum systems—a behavior known as "quantum scars." "In our first joint paper on quantum scars, published in Nature Physics, we demonstrated this unusual phenomenon on a superconducting quantum processor: a specially prepared system repeatedly returned close to its starting configuration," said Papić.
"That work led us to ask whether these unusual motions could be part of a much richer landscape, and whether a quantum processor could take an active role in discovering it." Drawing inspiration from their previous observations, the researchers set out to develop a method to search for hidden patterns of regular motion within otherwise chaotic quantum behavior, or, in other words, identify "islands" of regular motion in a "sea" of quantum chaotic behavior. The researchers tested their approach on a 24-qubit ladder system selected from a superconducting quantum processor containing more than 100 qubits. The processor worked together with an ordinary computer in a repeated loop.
Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly. "We prepared the quantum system, let it evolve briefly, and collected measurements," explained Papić. "The ordinary computer then uses those measurements to find a relatively simple quantum state that closely matches the result.
Extract — continue reading at the source.
