Efficient verification of continuous-variable quantum states and devices without assuming identical and independent operations

TL;DR

This paper introduces reliable protocols for verifying multimode continuous-variable quantum states and devices without assuming identical and independent operations, addressing realistic scenarios with correlated noise and adversarial conditions.

Contribution

It presents the first verification protocols for continuous-variable quantum states and devices that do not rely on the i.i.d. assumption, applicable to various quantum states and operations.

Findings

Protocols work under non-i.i.d. conditions

Applicable to Gaussian and non-Gaussian states

Effective for noisy state amplification and purification

Abstract

Continuous-variable quantum information, encoded into infinite-dimensional quantum systems, is a promising platform for the realization of many quantum information protocols, including quantum computation, quantum metrology, quantum cryptography, and quantum communication. To successfully demonstrate these protocols, an essential step is the certification of multimode continuous-variable quantum states and quantum devices. This problem is well studied under the assumption that multiple uses of the same device result into identical and independently distributed (i.i.d.) operations. However, in realistic scenarios, identical and independent state preparation and calls to the quantum devices cannot be generally guaranteed. Important instances include adversarial scenarios and instances of time-dependent and correlated noise. In this paper, we propose the first set of reliable protocols for verifying multimode continuous-variable entangled states and devices in these non-i.i.d scenarios. Although not fully universal, these protocols are applicable to Gaussian quantum states, non-Gaussian hypergraph states, as well as amplification, attenuation, and purification of noisy coherent states.