Scalable High-Dimensional Time-Bin QKD

Nurul T. Islam

Nicola Montaut, Stefania Sciara, Mario Chemnitz +9 more

High-dimensional time-bin analyzers are essential for characterizing quantum states in photonic systems. We present advancements in fiber- and chip-based platforms for generating and analyzing time-bin entanglement, emphasizing ultrastable fiber architectures, scalable quantum key distribution, and post-selection-free measurements, enabling robust and scalable quantum communication and processing.

Nurul T. Islam, Charles Ci Wen Lim, Clinton Cahall +3 more

Abstract We propose and experimentally demonstrate a new scheme for measuring high-dimensional phase states using a two-photon interference technique, which we refer to as quantum-controlled measurement. Using this scheme, we implement a d -dimensional time-phase quantum key distribution (QKD) system and achieve secret key rates of 5.26 and 8.65 Mbps using d = 2 and d = 8 quantum states, respectively, for a 4 dB channel loss, illustrating that high-dimensional time-phase QKD protocols are advantageous for low-loss quantum channels. This work paves the way for practical high-dimensional QKD protocols for metropolitan-scale systems. Furthermore, our results apply equally well for other high-dimensional protocols, such as those using the spatial degree-of-freedom with orbital angular momentum states being one example.

Nurul T. Islam

June‐Koo Kevin Rhee

Stefania Sciara, Hao Yu, Mario Chemnitz +20 more

Encoding information in time-bin entangled photonic systems enables the implementation of quantum technologies that are compatible with both integrated and fiber frameworks. Extending such an encoding to high-dimensional (qudit) time-bin entanglement provides a tool towards scaling the information capacity, noise resilience, and scalability of information processing. Here, we demonstrate scalable time-bin entangled qudits in a programmable photonic chip, as well as in a fully fibered coupled loop system.