Overview
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Explore groundbreaking research on quantum circuit complexity in this conference talk where Jonas Haferkamp from Saarland University presents novel findings on constructing random unitaries with minimal circuit depth. Learn how random quantum circuits on any geometry, including one-dimensional configurations, can form approximate unitary designs over n qubits using only logarithmic depth - a result that improves exponentially over previous constructions. Discover the construction of pseudorandom unitaries (PRUs) in 1D circuits with polylogarithmic depth and in all-to-all-connected circuits with polyloglog depth, achieving optimal scaling in all cases. Understand the innovative approach of combining local random unitaries on logarithmic or polylogarithmic-sized qubit patches to create global random unitaries across all n qubits, while maintaining low complexity and generating only short-range entanglement despite being indistinguishable from exponentially complex unitaries. Examine the practical applications of these results, including proving the equivalence of classical shadows using 1D log-depth Clifford circuits to those with deep circuits, demonstrating superpolynomial quantum advantage in learning low-complexity physical systems, and establishing quantum computational hardness for recognizing topological phases of matter.
Syllabus
Jonas Haferkamp (Saarland University): Random unitaries in extremely low depth
Taught by
Centrum Fizyki Teoretycznej PAN