The discussion about quantum computing usually swings between long-term promises and headlines hard to bring down to everyday reality. However, in the fields of cybersecurity and core telecommunications, the debate is becoming very concrete: how to protect data traffic in transit in a future where certain quantum systems could weaken classical cryptography. In this context, Colt Technology Services has announced the completion of a transatlantic trial that, according to the company, is the first of its kind: transmitting data at 100 GbE over land and submarine networks across the Atlantic using quantum-resistant encryption.
This milestone is significant for a simple reason: the North Atlantic is one of the most critical corridors on the planet for internet traffic and the digital economy, and the Grace Hopper submarine cable — part of the infrastructure used in the test — has become a strategic piece due to its capacity. Colt emphasizes that this segment provides 352 Tbps of capacity and reinforces its role as a “backbone” of global connectivity between Europe and the United States, supporting everything from enterprise cloud services to streaming and AI workloads.
Exactly what has been tested: 100 GbE with post-quantum protection, from land to deep sea
The core of the announcement is twofold. First, Colt claims to have successfully transmitted traffic at 100 GbE securely over its optical infrastructure across land routes and the transatlantic submarine system. Second, it specifies the technological basis of the “shielding”: a combination of solutions from Nokia and Adtran.
Specifically, Colt mentions using Nokia’s Pre-Shared Key (PSK) technology and Adtran’s post-quantum cryptography (PQC) mechanisms based on ML-KEM. In business terms, this means strengthening how keys and encryption sessions are exchanged and protected by incorporating methods designed to withstand scenarios where quantum computing power could accelerate attacks against traditional cryptographic schemes.
Although the announcement describes it as a “trial,” the relevant detail lies in the scale: it is not about an isolated laboratory or a small segment, but a demonstration that covers routes genuinely matter to banks, insurers, multinationals, and cloud operators.
Why the transatlantic route matters more than ever
Submarine infrastructure is often invisible to the general public but is decisive. Cables like Grace Hopper connect large economic regions and data center clusters, with direct implications for latency, capacity, and resilience. In the specific case of Grace Hopper, technical references describe a system with 16 fiber pairs and a total design capacity of 352 Tbps, with an main route between the U.S. East Coast and the UK, plus a branch toward Spain (Bilbao). That capacity explains why it has become a natural backbone for digital services growth across continents.
Meanwhile, the rise of Artificial Intelligence has added pressure on these routes. Not only due to content consumption but also for data replication, cloud-to-cloud flows, distributed training, inference across multiple regions, and moving large volumes of information between data centers. In this scenario, “in transit” security shifts from a technical requirement to a business continuity condition.
What “quantum-safe” means and why it’s not a single technology
In the post-quantum debate, various approaches coexist, and Colt lists them as part of its roadmap. The company assures that later in 2026 it will offer “quantum-resilient” services that will include:
- PSK (Pre-Shared Key)
- PQC (Post-Quantum Cryptography)
- QKD (Quantum Key Distribution)
- Hybrid models combining multiple techniques
Each approach responds to different balances between practicality, maturity, cost, and deployment speed. PQC aims to maintain secure communications with algorithms designed to resist more powerful threats; QKD focuses on exchanging keys with properties rooted in quantum mechanics; and hybrid models seek to reduce risks by combining classical and post-quantum mechanisms during transition periods. Market-wise, this variety reveals a reality: there will not be a “single migration” for everyone but sector-specific, data criticality, and regulatory dependence strategies.
Sectors under pressure: finance, healthcare, and government
Colt positions its future offering as ideal for organizations needing resilient global connectivity and enhanced protection for sensitive data. Among the profiles it highlights are:
- Financial institutions, due to data value and regulatory traceability.
- Healthcare providers, because of the sensitivity of records and clinical data.
- Governments and defense, for national security and compliance considerations.
- Enterprise and technology partners integrating post-quantum security into networks and platforms.
The subtext is clear: even before the threat fully materializes, many players are acting based on prudence. In cybersecurity, preparation often begins before the risk becomes routine, as cryptographic changes are slow: inventory, compatibility checks, testing, gradual deployment, and coexistence of systems.
A step further in a series of pilots, including the “leap” toward space-based quantum cryptography
The announcement also fits into a sequence of tests. Colt recalls previous pilots to protect traffic on its optical network and points to developments around space-based quantum cryptography, a line of work conducted with technological partners. The sector’s takeaway is that post-quantum protection is moving toward a concept of end-to-end security: from terrestrial networks to submarine routes, and from there to scenarios where space can expand key distribution possibilities.
The signal from the market: the post-quantum transition is now infrastructure, not just theory
The value of Colt’s trial is not just in the “world’s first” headline but in its operational message: post-quantum security is starting to be implemented in the most demanding environment — the core network supporting entire economies. If this layer shifts, the rest of the ecosystem — operators, big companies, cloud providers, integrators — receives a signal: the transition is no longer a strategic document but a concrete engineering reality.
The most important open question for clients and regulators is: when will these types of tests become mass-market services, with SLAs, pricing, metrics, interoperability, and sustainable lifecycles? Colt believes this will happen throughout 2026, with a portfolio combining PSK, PQC, QKD, and hybrids across land and submarine routes.