2024/11/07 by David Gosset, Robin Kothari, Gosset, David +4 · 2 voices · 9 citations
Computer Science · Physics and Astronomy · #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications
paper · pdf · doi:10.22331/q-2026-07-22-2168
Quantum 10, 2168 (2026). https://doi.org/10.22331/q-2026-07-22-2168 How many T gates are needed to approximate an arbitrary n-qubit quantum state to within error ε? Improving prior work of Low, Kliuchnikov, and Schaeffer, we show that the optimal asymptotic scaling is Θ(√(2nlog(1/ε))+log(1/ε)) if we allow ancilla qubits. We also show that this is the optimal T-count for implementing an arbitrary diagonal n-qubit unitary to within error ε. We describe applications in which a tensor product of many single-qubit unitaries can be synthesized in parallel for the price of one.