An efficient quantum state verification framework and its application to bosonic systems

TL;DR

This paper presents a scalable, semi-device independent framework for verifying large quantum systems, especially bosonic states, using efficient classical post-processing and Gaussian measurements, improving trust and calibration of quantum devices.

Contribution

It introduces a novel, efficient verification framework combining fidelity witnesses with measurement back-propagation, tailored for bosonic systems and Gaussian measurements.

Findings

Protocols are semi-device independent and practical.

Efficient verification of large bosonic states achieved.

Improves calibration and trust in quantum devices.

Abstract

Modern quantum devices are highly susceptible to errors, making the verification of their correct operation a critical problem. Usual tomographic methods rapidly become intractable as these devices are scaled up. In this paper, we introduce a general framework for the efficient verification of large quantum systems. Our framework combines robust fidelity witnesses with efficient classical post-processing to implement measurement back-propagation. We demonstrate its usefulness by focusing on the verification of bosonic quantum systems, and developing efficient verification protocols for large classes of target states using the two most common types of Gaussian measurements: homodyne and heterodyne detection. Our protocols are semi-device independent, designed to function with minimal assumptions about the quantum device being tested, and offer practical improvements over previous existing approaches. Overall, our work introduces efficient methods for verifying the correct preparation of complex quantum states, and has consequences for calibrating large quantum devices, witnessing quantum properties, supporting demonstrations of quantum computational speedups and enhancing trust in quantum computations.