Quantum communication with ultrafast time-bin qubits

TL;DR

This paper demonstrates the experimental feasibility of using ultrafast picosecond time-bin states of light for quantum communication, enabling high-rate, stable quantum key distribution over fiber networks.

Contribution

It introduces a method to detect superpositions of ultrafast time-bin states with high phase stability, advancing quantum communication technology.

Findings

Successful measurement of ultrafast time-bin superpositions

High phase stability in temporal state detection

Potential for high-rate quantum key distribution

Abstract

The photonic temporal degree of freedom is one of the most promising platforms for quantum communication over fiber networks and free-space channels. In particular, time-bin states of photons are robust to environmental disturbances, support high-rate communication, and can be used in high-dimensional schemes. However, the detection of photonic time-bin states remains a challenging task, particularly for the case of photons that are in a superposition of different time-bins. Here, we experimentally demonstrate the feasibility of picosecond time-bin states of light, known as ultrafast time-bins, for applications in quantum communications. With the ability to measure time-bin superpositions with excellent phase stability, we enable the use of temporal states in efficient quantum key distribution protocols such as the BB84 protocol.