QKD Systems

Long-Distance QKD System LD


Ultimate QKD performance over long distances

Quantum computing is threatening to render public key encryption techniques insecure, with data in transit particularly vulnerable to attack. QKD (Quantum Key Distribution) provides the answer, enabling quantum-safe cryptography across fiber networks.

Development of long-distance QKD technology has been a significant challenge for manufacturers, as the quantum signal decreases in strength exponentially as fiber length increases.

The LD system overcomes this challenge. It uses Toshiba's unique, patented technology to ensure exceptionally high secure key rates over distances of 93 miles or more. Deployed using a dedicated QKD fiber, the LD system also offers simple setup, auto alignment and real-time optimization.

This combination supports a greater number of demanding use cases and reduces CAPEX, as fewer QKD systems are required to provide quantum security over long-range connections. It also reduces business risk by offering sufficient capacity to support future network demands, and even enables older, degraded fiber to become quantum-secure.

It's high-performance quantum security for the long haul.


Ensures quantum-secure networking over distances of 90 miles+
Optimizes CAPEX, with fewer systems required to meet your distance needs
Proprietary active stabilization technology that adapts to the network environment

Features & Benefits


Key Exchange Protocol
Toshiba T12 protocol (efficient BB84 protocol with decoy states and phase encoding)
Quantum Wavelength
1550 nm (C-band)
Fiber requirement
Two fibers required
Multiplexing Compatibility
Limited bandwidth multiplexing supported
Secure Key Rate
300 kb/s at 10 dB channel loss
Maximum loss (ideal SM fiber)
30 dB specified loss budget
Maximum Range (ideal SM fiber)
93 miles+
Detection Technology
Proprietary self-differencing semiconductor detectors
Security Parameter
Key failure probability < 1 x 10-10, corresponding to less than once in 30,000 years
Monitoring Functions
SNMP v2 & v3, GUI, CLI
Key Management
Key Management System (key generation, key storage, proactive/on-demand key delivery). System supporting ETSI GS QKD 014 industry standard key delivery API
CE, UKCA: EN 55032:2015+A11, EN 55035:2017+A11, EN 61000-3-2:2014, EN 61000-3-3:2013, EN 63000:2018. IEC 62638-1:2014, IEC 62638-1:2020, BS EN 60825-1:2014, IEC 60825-2:2010,FCC: 47 CFR, Part 15, FDA: 21 CFR, Part J
Standard 19’’ rack mount (3U height)

Latest Toshiba LD resources


Toshiba QKD Systems LD & MU Datasheet (PDF, 1 MB)

Latest product details and specifications for Multiplexing MU and Long Distance LD QKD systems. Discover all the key details on our Long Distance and Multiplexing QKD systems - download now.

Quantum Key Distribution and Blockchain (PDF, 1 MB)

The power of quantum computing technology can challenge the security of any system reliant on certain mathematical algorithms, meaning it could undermine the security that blockchain promises. Quantum Key Distribution is the answer. This paper will explore the evolution of QKD, its future, and a real-world application research study with Toshiba, JPMorgan Chase and Ciena.

[EXTERNAL] Experimental quantum key distribution beyond the repeaterless secret key capacity (Nature)


[EXTERNAL] Overcoming the rate–distance limit of quantum key distribution without quantum repeaters (Nature)


[EXTERNAL] A Quantum Light-Emitting Diode for the Standard Telecom Window Around 1,550 nm (Nature)

A chart illustrating high reliability

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