Multimode CV‐QKD with non‐Gaussian operations

Abstract

Summary Non‐Gaussian operations have been studied intensively in recent years due to their ability to increase the secret key rate for certain CV‐QKD protocols. However, most previous studies on such protocols are carried out in a single‐mode setting, even though in reality any quantum state contains multimode components in frequency space. In this work, we investigate the use of non‐Gaussian operations in a multimode CV‐QKD system. Our main finding is that, contrary to single‐mode CV‐QKD systems, in generic multimode CV‐QKD systems, it is possible to use non‐Gaussian operations to increase the optimized secret key rate. More specifically, we find that at losses of order 30dB, which represents a distance of order 160km and the effective maximum distance for CV‐QKD, the key rate for multimode non‐Gaussian operations can be orders of magnitude higher than single‐mode operations. Our results are important for real‐world CV‐QKD systems, especially those dependent on quantum error correction—a process that requires non‐Gaussian effects.

Quantum network based on non-classical light

“…Recently, Diamanti et al [6] reviewed practical challenges in QKD. DV QKD [5,6] and CV QKD [37,[45][46][47][48][49][50] are developing in parallel. The security of the QKD system is limited by the imperfection of the devices [6], for example side-channel attacks [51][52][53].…”

Enhancing Continuous Variable Quantum Teleportation using Non-Gaussian Resources

“…Remarkably, states commonly referred to as non-Gaussian states have shown higher amounts of entanglement (at a given energy) in comparison to their Gaussian counterparts [12], [13]. In CV-QKD, non-Gaussian states have been successfully used directly to increase key rates [12], [14], including in the context of spacebased CV-QKD [15], [16]. Non-Gaussian states have also been shown to allow for long-distance state transmission by means of quantum repeaters [3], [17].…”

Drastic increase of key rate in continuous‐variable quantum key distribution using multimode states and non‐Gaussian operations

“…Quantum cryptography provides information-theoretic security via the laws of physics, and it has attracted much attention recently. [1][2][3][4][5][6] Continuous-variable quantum key distribution (CV QKD) has garnered great interest over the past decade because CV QKD has the advantage of "off-the-shelf" technology based on efficient homodyne (or heterodyne) detectors, and the fact that CV QKD protocols potentially provide a realistic route to high QKD key rates. Thus, increasing the secret key rate and the transmission distance of CV-QKD protocols are topics of much ongoing research.…”

“…In a recent article published in Quantum Engineering by He et al 6 from the University of New South Wales, multimode states are combined with the ideas of non-Gaussian operations, which increases the optimized key rate of entanglement-based CV-QKD systems relative to the schemes that do not employ non-Gaussian operations. He et al investigated three types of multimode non-Gaussian operations, namely, photon subtraction, photon addition, and photon catalysis.…”