New study probes entanglement in noisy quantum processors

Researchers are discovering a counterintuitive relationship between local measurements and long-range entanglement in quantum processors. The study reveals that sampling from even simple, constant-depth 2D circuits can be computationally difficult, despite being relatively easy to create. This difficulty arises because local measurements can unexpectedly convert short-range entanglement into long-range entanglement, a phenomenon linked to the efficiency of algorithms used to simulate these circuits. Understanding this dynamic is crucial for determining if noisy 2D random-circuit sampling can be efficiently simulated, as the measurement-induced entanglement serves as an indicator of the algorithm. Constant-depth 2D circuits, despite being relatively simple to create, present a surprising challenge to classical computation; researchers…