Halving the cost of quantum multiplexed rotations

Abstract

We improve the number of $T$ gates needed for a $b$-bit approximation of a multiplexed quantum gate with $c$ controls applying $n$ single-qubit arbitrary phase rotations from $4nb+\mathcal{O}(\sqrt{cnb})$ to $2nb+\mathcal{O}(\sqrt{cnb})$, and reduce the number of qubits needed by up to a factor of two. This generic quantum circuit primitive is found in many quantum algorithms, and our results roughly halve the cost of state-of-art electronic structure simulations based on qubitization of double-factorized or tensor-hypercontracted representations. We achieve this by extending recent ideas on stochastic compilation of quantum circuits to classical data and discuss space-time trade-offs and concentration of measure in its implementation.

9 pages

References in corpus (2)

• Synthesis of Quantum Logic Circuits
• Application of a resource theory for magic states to fault-tolerant quantum computing