An international team of researchers has shown that quantum systems can appear memoryless in one framework while retaining memory in another, challenging a fundamental assumption in physics. Published in PRX Quantum, the study involved scientists from the University of Turku, University of Milan, and Nicolaus Copernicus University.
In classical physics, a system is considered memoryless if its future depends only on its present state. However, quantum systems behave differently, as information can be stored and revealed in ways that depend on how the system is observed.
The researchers compared two key quantum frameworks: one based on the evolution of quantum states, linked to Erwin Schrödinger, and another focused on observable quantities, associated with Werner Heisenberg. While both approaches yield identical experimental results, they reveal different aspects of memory.
The study finds that certain memory effects are visible only in one framework and not the other, meaning a system can seem memoryless under one description yet show clear memory under another.
This insight has implications for quantum technologies, where understanding and controlling memory effects is critical for managing noise and improving device performance.
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