Tight bound for the total time in digital-analog quantum computation

TL;DR

This paper establishes a tight linear bound on the total evolution time in digital-analog quantum computing, improving resource estimation and enabling better comparison with other quantum approaches.

Contribution

It provides the first tight bound for the total time in DAQC, refining previous suboptimal estimates and aiding in resource planning for quantum simulations.

Findings

Total time scales linearly with the number of couplings.

Enables precise estimation of quantum resource requirements.

Facilitates comparison between DAQC and other quantum computing methods.

Abstract

Digital-analog quantum computing (DAQC) is a universal computational paradigm that combines the evolution under an entangling Hamiltonian with the application of single-qubit gates. Since any unitary operation can be decomposed into a sequence of evolutions generated by two-body Hamiltonians, DAQC is inherently well-suited for realizing such operations. Suboptimal upper bounds for the total time required to perform these evolutions have been previously proposed. Here, we improve these limits by providing a tight bound for this crucial parameter, which shows a linear dependence with the number of couplings. This result enables a precise estimation of the time resources needed for quantum simulations and quantum algorithms implemented within the DAQC framework, facilitating a rigorous comparison with other approaches.