Implementation of Continuous-Variable Quantum Key Distribution with Composable and One-Sided-Device-Independent Security Against Coherent Attacks (1406.6174v4)

Abstract: Secret communication over public channels is one of the central pillars of a modern information society. Using quantum key distribution this is achieved without relying on the hardness of mathematical problems which might be compromised by improved algorithms or by future quantum computers. State-of-the-art quantum key distribution requires composable security against coherent attacks for a finite number of distributed quantum states as well as robustness against implementation side-channels. Here, we present an implementation of continuous-variable quantum key distribution satisfying these requirements. Our implementation is based on the distribution of continuous-variable Einstein-Podolsky-Rosen entangled light. It is one-sided device independent, which means the security of the generated key is independent of any memory-free attacks on the remote detector. Since continuous-variable encoding is compatible with conventional optical communication technology, our work is a crucial step towards practical implementations of quantum key distribution with state-of-the-art security based solely on telecom components.

Overview of Continuous-Variable Quantum Key Distribution with Composable and One-Sided Device-Independent Security

The paper presents a significant advancement in quantum key distribution (QKD) by delineating the implementation of continuous-variable QKD with composable and one-sided device-independent (1sDI) security against coherent attacks. It addresses several pivotal aspects in the field of quantum cryptography, notably the robustness against implementation side-channel attacks and the practicality of deploying QKD systems with telecom components.

Key Aspects and Results

The authors introduce a QKD system leveraging continuous-variable Einstein-Podolsky-Rosen (EPR) entangled light sourced from two squeezed vacuum beams. This implementation marks a departure from traditional approaches requiring complex quantum mechanics computations susceptible to modifications with advances in algorithms or quantum computing power. With the EPR source located securely in Alice's private space, the paper argues this system does not necessitate assumptions on Bob's detector, effectively rendering it one-sided device-independent. This setup facilitates the generation of secret keys secure against several memoryfree attacks including calibration, wavelength, and saturation assaults on Bob's local oscillator and homodyne detector.

Remarkably, the authors demonstrate a secure key rate of about 0.1 bits per sample over a fiber-equivalent 2.7 km, estimating maximum feasible distances up to 4.8 km for QKD links with the presented composable security. This accomplishment is supported by a robust error reconciliation algorithm reaching efficiencies close to the Shannon limit, thereby crucially enhancing the practical viability of such systems in real-world applications.

Implications and Future Directions

This work holds substantial implications for the operational scope and deployment of quantum cryptographic systems. The integration with existing optical telecom technology through continuous-variable encoding fosters a pathway towards expanded deployment in urban and metropolitan areas, thereby potentially revolutionizing secure communications.

Theoretical discussions suggest the possibility of extending operational distances through reverse reconciliation techniques or improvements in fiber optics technologies. However, the current distance limits imposed by coherent attacks require a reevaluation and expansion of security proofs to truly exploit collective attack scenarios over infinitely large distributed quantum states.

Future research might pivot towards optimizing security proofs to further minimize the dependency on specialized quantum sources, possibly transitioning entirely towards Gaussian modulation of coherent states. Such developments could culminate in truly industry-ready implementations of 1sDI QKD systems, reducing infrastructure complexity and accelerating adoption across broader domains.

In summary, the paper explores ground-breaking avenues in quantum cryptography with its implementation of a robust and secure QKD system against coherent attacks, contributing significantly to the expansive field of quantum communication technologies and paving the way for their practical realization in everyday scenarios.