Orchestrated Trios: Compiling for Efficient Communication in Quantum Programs with 3-Qubit Gates

TL;DR

This paper introduces Orchestrated Trios, a new quantum compiler approach that optimizes multi-qubit gate compilation and routing, significantly reducing error-prone operations and improving success rates on IBM quantum hardware.

Contribution

It proposes a novel compiler structure that first decomposes to three-qubit gates, then routes and finishes decomposition, enabling architecture-tuned optimizations and reducing communication overhead.

Findings

35% decrease in two-qubit gate count on IBM Johannesburg

23% increase in success rate of a single Toffoli gate

344% average increase in success rate for benchmark algorithms

Abstract

Current quantum computers are especially error prone and require high levels of optimization to reduce operation counts and maximize the probability the compiled program will succeed. These computers only support operations decomposed into one- and two-qubit gates and only two-qubit gates between physically connected pairs of qubits. Typical compilers first decompose operations, then route data to connected qubits. We propose a new compiler structure, Orchestrated Trios, that first decomposes to the three-qubit Toffoli, routes the inputs of the higher-level Toffoli operations to groups of nearby qubits, then finishes decomposition to hardware-supported gates. This significantly reduces communication overhead by giving the routing pass access to the higher-level structure of the circuit instead of discarding it. A second benefit is the ability to now select an architecture-tuned Toffoli decomposition such as the 8-CNOT Toffoli for the specific hardware qubits now known after the routing pass. We perform real experiments on IBM Johannesburg showing an average 35% decrease in two-qubit gate count and 23% increase in success rate of a single Toffoli over Qiskit. We additionally compile many near-term benchmark algorithms showing an average 344% increase in (or 4.44x) simulated success rate on the Johannesburg architecture and compare with other architecture types.