Pauli Partitioning with Respect to Gate Sets

TL;DR

This paper explores efficient partitioning of Pauli operators for simultaneous measurement in quantum algorithms, proposing heuristics and conjectures that could significantly reduce measurement complexity, especially for variational quantum eigensolvers.

Contribution

It introduces a heuristic-based upper bound for Pauli operator partitioning and conjectures that Clifford operations can linearly reduce measurement parts, with supporting evidence.

Findings

Heuristic bounds for partitioning random Pauli sets.

Conjecture that Clifford operations reduce parts linearly.

Implications for faster measurements in quantum algorithms.

Abstract

Measuring the expectation value of Pauli operators on prepared quantum states is a fundamental task in a multitude of quantum algorithms. Simultaneously measuring sets of operators allows for fewer measurements and an overall speedup of the measurement process. We investigate the task of partitioning a random subset of Pauli operators into simultaneously-measurable parts. Using heuristics from coloring random graphs, we give an upper bound for the expected number of parts in our partition. We go on to conjecture that allowing arbitrary Clifford operators before measurement, rather than single-qubit operations, leads to a decrease in the number of parts which is linear with respect to the lengths of the operators. We give evidence to confirm this conjecture and comment on the importance of this result for a specific near-term application: speeding up the measurement process of the variational quantum eigensolver.