# Universal and Operational Benchmarking of Quantum Memories

## TL;DR

This paper introduces a universal, operational benchmark for quantum memories that quantifies their robustness, resource requirements, and potential to outperform classical strategies across various settings, demonstrated on IBM hardware.

## Contribution

The authors develop a new benchmark that is universally applicable, efficiently computable, and experimentally accessible for evaluating quantum memories across different platforms.

## Key findings

- Benchmark effectively quantifies quantum memory capabilities.
- Demonstrated on IBM Q hardware with error-suppression techniques.
- Provides insights into non-Markovian noise effects.

## Abstract

Quantum memory -- the capacity to store and faithfully recover unknown quantum states -- is essential for quantum-enhanced technology. There is thus a pressing need for operationally meaningful means to benchmark candidate memories across diverse physical platforms. Here we introduce a universal benchmark distinguished by its relevance across multiple key operational settings, exactly quantifying (1) the memory's robustness to noise, (2) the number of noiseless qubits needed for its synthesis, (3) its potential to speed up statistical sampling tasks, and (4) performance advantage in non-local games beyond classical limits. The measure is analytically computable for low-dimensional systems and can be efficiently bounded in experiment without tomography. We thus illustrate quantum memory as a meaningful resource, with our benchmark reflecting both its cost of creation and what it can accomplish. We demonstrate the benchmark on the five-qubit IBM Q hardware, and apply it to witness efficacy of error-suppression techniques and quantify non-Markovian noise. We thus present an experimentally accessible, practically meaningful, and universally relevant quantifier of a memory's capability to preserve quantum advantage.