About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Publication
IEEE TQE
Paper
Harnessing the Power of Long-Range Entanglement for Clifford Circuit Synthesis
Abstract
In superconducting architectures, limited connectivity remains a significant challenge for the synthesis and compilation of quantum circuits. We consider models of entanglement-assisted computation where long-range operations are achieved through injections of large Greenberger-Horne-Zeilinger (GHZ) states. These are prepared using ancillary qubits acting as an 'entanglement bus,' unlocking global operation primitives such as multiqubit Pauli rotations and fan-out gates. We derive bounds on the circuit size for several well-studied problems, such as CZ circuit, CX circuit, and Clifford circuit synthesis. In particular, in an architecture using one such entanglement bus, we give a synthesis scheme for arbitrary Clifford operations requiring at most 2n+1 layers of entangled state injections, which can be computed classically in O(n3) time. In a square-lattice architecture with two entanglement buses, we show that a graph state can be synthesized using at most ⌈ 1/2n⌉ +1 layers of GHZ state injections, and Clifford operations require only ⌈ 3/2 n ⌉ + O(√) layers of GHZ state injections.