Researchers at the University of California, Irvine announced on April 13 that they have found a way to reverse ‘quantum scrambling,’ a process that causes information loss in quantum computing systems.
Quantum scrambling is a challenge for current quantum computers, as it leads to the loss of stored data. This discovery could help computers preserve information that would otherwise be lost during this process, which is important for advancing quantum computing and its applications.
Thomas Scaffidi, assistant professor of physics and astronomy and lead author of the new Physical Review Letters study, said: “My work is on understanding how this scrambling of quantum information works and in understanding how it emerges. We’re trying to figure out if the information is still there in some form and if we can reverse the scrambling process completely.”
The team explained that while conventional computers use bits storing values as either 0 or 1, qubits—the fundamental unit in quantum computing—can store both values simultaneously. When qubits interact within a chip, encoded data spreads among them until it appears lost. “Let’s say you have many qubits that are all talking to each other and exchanging information,” Scaffidi said. “If you try to locally encode some information in the qubits, after a while, there’s going to be the scrambling effect – the encoded information is going to spread out over many qubits and will be effectively lost, and you won’t be able to recover it. That’s an issue if you want to retrieve that information or do calculations with it.”
Scaffidi’s graduate student Rishik Perugu found evidence suggesting this behavior could be reversed by carefully tuning interventions within these systems. Scaffidi said: “At the microscopic level, our universe seems to be reversible in time, so if you think of two particles colliding, if you watch a movie of two particles colliding, the movie would look sensible if you played it forward or backwards.” He added: “It happens to be a very universal property… The conclusion is that it is possible to reverse it but requires an extremely fine-tuned and very fine level of control on your system.”
Perugu’s calculations provided momentum for publishing these findings after previous delays with the project. “The project had stalled for a while before Rishik joined,” Scaffidi said. “His work gave it new momentum, and he played a central role in making the new paper happen.” The research received funding from a U.S. Department of Energy Early Career Research Program Award.
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This breakthrough may influence future developments in quantum technology by enabling better control over data retention within advanced computing systems.