Low-error encoder for time-bin and decoy states for quantum key distribution

Fuente: arXiv
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Main Authors: Scalcon, Davide, Bazzani, Elisa, Vallone, Giuseppe, Villoresi, Paolo, Avesani, Marco
Format: Preprint
Published: 2023
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author Scalcon, Davide
Bazzani, Elisa
Vallone, Giuseppe
Villoresi, Paolo
Avesani, Marco
author_facet Scalcon, Davide
Bazzani, Elisa
Vallone, Giuseppe
Villoresi, Paolo
Avesani, Marco
contents Time-bin encoding has been widely used for implementing quantum key distribution (QKD) on optical fiber channels due to its robustness with respect to drifts introduced by the optical fiber. However, due to the use of interferometric structures, achieving stable and low intrinsic Quantum Bit Error rate (QBER) in time-bin systems can be challenging. A key device for decoy-state prepare & measure QKD is represented by the state encoder, that must generate low-error and stable states with different values of mean photon number. Here we propose the MacZac (Mach-Zehder-Sagnac), a time-bin encoder with ultra-low intrinsic QBER (<2e-5) and high stability. The device is based on nested Sagnac and Mach-Zehnder interferometers and uses a single phase modulator for both decoy and state preparation, greatly simplifying the optical setup. The encoder does not require any active compensation or feedback system and it can be scaled for the generation of states with arbitrary dimension. We experimentally realized and tested the device performances as a stand alone component and in a complete QKD experiments. Thanks to the capacity to combine extremely low QBER, high stability and experimental simplicity the proposed device can be used as a key building block for future high-performance, low-cost QKD systems.
format Preprint
id arxiv_https___arxiv_org_abs_2311_02059
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Low-error encoder for time-bin and decoy states for quantum key distribution
Scalcon, Davide
Bazzani, Elisa
Vallone, Giuseppe
Villoresi, Paolo
Avesani, Marco
Quantum Physics
Time-bin encoding has been widely used for implementing quantum key distribution (QKD) on optical fiber channels due to its robustness with respect to drifts introduced by the optical fiber. However, due to the use of interferometric structures, achieving stable and low intrinsic Quantum Bit Error rate (QBER) in time-bin systems can be challenging. A key device for decoy-state prepare & measure QKD is represented by the state encoder, that must generate low-error and stable states with different values of mean photon number. Here we propose the MacZac (Mach-Zehder-Sagnac), a time-bin encoder with ultra-low intrinsic QBER (<2e-5) and high stability. The device is based on nested Sagnac and Mach-Zehnder interferometers and uses a single phase modulator for both decoy and state preparation, greatly simplifying the optical setup. The encoder does not require any active compensation or feedback system and it can be scaled for the generation of states with arbitrary dimension. We experimentally realized and tested the device performances as a stand alone component and in a complete QKD experiments. Thanks to the capacity to combine extremely low QBER, high stability and experimental simplicity the proposed device can be used as a key building block for future high-performance, low-cost QKD systems.
title Low-error encoder for time-bin and decoy states for quantum key distribution
topic Quantum Physics
url https://arxiv.org/abs/2311.02059