Quantum Computers: An Impending Revolution and a Threat to Modern Cryptography

For a long time, quantum computers were associated more with laboratories than with the real world. However, the year 2026 shows that development is shifting from fragile experiments to error-correcting systems. For the average user, this doesn’t change anything yet, but for banks, governments, and companies, it’s a clear signal: the encryption on which the internet relies will eventually need to be replaced. In this article, we explain what quantum computers are, what they could be used for, and why people are already talking about post-quantum cryptography.

What Are Quantum Computers and How Do They Differ from Conventional Ones

A conventional computer operates using bits. At any given moment, each bit has a value of either 0 or 1. A quantum computer uses qubits, which are governed by the laws of quantum physics. A qubit can be in a state that is a combination of both 0 and 1 (known as superposition), and multiple qubits can be interconnected (quantum entanglement). Thanks to this, a quantum computer can perform certain tasks in a completely different way than a classical computer.

It’s important not to fall for the myth that a quantum computer is a “faster classical computer.” It isn’t. It is not suitable for most everyday tasks, from writing text to streaming video. Its power is only evident for certain types of problems for which special algorithms exist.

Bits and Qubits at a Glance

• Bit: a value of 0 or 1, stable and easily replicable.
• Qubit: a combination of the states 0 and 1, highly sensitive to environmental interference.
• Consequence: Qubits make errors, which is why development is focused on error correction.

Where Will Quantum Computers Be in 2026?

The key challenge is error rates. A single reliable, so-called logical qubit is created by combining multiple physical qubits with error correction. According to Forrester’s report, *The State of Quantum Computing, 2026*, the industry’s focus is shifting from the number of physical qubits to logical qubits. The report also notes that fully fault-tolerant computers are still several years away and that hybrid systems—which combine quantum and classical computing—offer a faster path to practical applications.

In other words: progress is real, but a computer capable of breaking today’s encryption does not yet exist. Companies are also announcing ambitious plans, but these are their own goals, not guarantees.

Practical Applications: What Quantum Computers Could Change

Quantum computers are naturally suited for simulating quantum systems—such as molecules—and for certain optimization tasks. This potential will be realized gradually, and progress varies across different fields.

Drug development

The behavior of molecules is governed by quantum laws, and therefore their accurate simulation quickly reaches its limits on classical computers. In the future, quantum computers could help model interactions between a drug and a target protein and shorten the drug candidate discovery phase. However, this would not replace clinical trials.

Materials Engineering

A similar principle applies to the search for new materials, such as those for batteries, catalysts, or superconductors. More accurate simulations could reduce the number of costly laboratory experiments.

Complex Optimization

Logistics, transportation planning, production scheduling, and portfolio management are tasks with an enormous number of possibilities. Quantum and hybrid approaches are being explored as a way to solve such problems more efficiently. However, caution is needed when it comes to optimization: the advantage over well-tuned classical algorithms must be demonstrated in every case.

A Threat to Current Cryptography

Most public keys that protect online banking, HTTPS connections, and digital signatures rely on RSA and ECC (elliptic curve cryptography) algorithms. Their security depends on mathematical problems that are practically unsolvable for classical computers. The UK’s NCSC states that future large-scale, robust quantum computers would be able to solve these problems efficiently, thereby threatening asymmetric cryptography. In the technical literature, this is associated with Shor’s algorithm.

It is important to distinguish that it is primarily asymmetric cryptography (key exchange and signatures) that is at risk. Symmetric encryption, such as AES, can—according to the general consensus among experts—be strengthened with longer keys, although specific recommendations depend on the particular standards.

Store now, decrypt later

An attacker does not need to wait for a quantum computer to get started. They can already intercept and store encrypted communications today and decrypt them later, once they have a sufficiently powerful machine at their disposal. This scenario is referred to as “harvest now, decrypt later” or “store now, decrypt later.” It primarily affects data with a long lifespan: medical records, intellectual property, state secrets, and financial data. If this data is to remain confidential even after 2035, protection must begin sooner, not only when the threat arises.

Banking

Financial institutions process data with a long retention period and rely on digital signatures and encrypted connections. That is why they are among the sectors where migration is discussed the most. However, this is a massive undertaking: it is necessary to map out all instances where cryptography is used, from web servers and mobile apps to hardware modules and suppliers.

Cryptocurrencies

Bitcoin and other networks use digital signatures based on elliptic curves (ECDSA, Schnorr). In the first half of 2026, BIP-360 was added to Bitcoin’s official proposal repository; it introduces a new type of output (P2MR) that reduces the exposure of public keys. However, this is only the first step, and according to comments, it does not replace the signature schemes with new post-quantum ones. More controversial is BIP-361, which calls for the gradual phasing out of older signatures and could potentially lock up unspent funds. The proposal is still under discussion, and the community does not even agree on how urgent the threat is. Some analysts view it more as a routine update cycle.

How the World Is Preparing: Post-Quantum Cryptography

The solution lies not in quantum physics, but in new mathematics. Post-quantum cryptography (PQC) is cryptography based on problems that should not be efficiently solvable even by a quantum computer. It runs on standard hardware and software.

NIST Standards

On August 13, 2024, the U.S. NIST finalized the first three PQC standards and designated them as ready for immediate use:

• FIPS 203 (ML-KEM): key exchange (encryption),
• FIPS 204 (ML-DSA): digital signatures,
• FIPS 205 (SLH-DSA): an alternative digital signature scheme.

At the same time, NIST urged system administrators to begin the transition as soon as possible. According to secondary sources, the draft document NIST IR 8547 anticipates that algorithms such as RSA and ECC will be phased out after 2030 and banned after 2035. This is a proposal, so please verify the current version of the document before making any plans.

The UK’s NCSC Timeline

The UK’s NCSC has published a three-phase migration plan:

• by 2028: set goals and prepare an initial migration plan,
• by 2031: carry out priority updates and refine the plan,
• by 2035: complete the migration of systems, services, and products.

The NCSC acknowledges that for a smaller group of less commonly used technologies, the 2035 deadline may be challenging.

What Companies and Organizations Can Do

1. Map out your cryptography. Identify where RSA, ECC, and other algorithms are used: in applications, certificates, devices, and even among suppliers.
2. Set priorities. Address data that must remain confidential for a long time and systems exposed to the network first.
3. Build cryptographic agility. Avoid hard-coded algorithms so they can be replaced later without having to rebuild the entire system.
4. Ask your vendors. Request their plan for transitioning to PQC and their support for new standards.
5. Expect a lengthy process. Migration is a multi-year program, not a one-time project.

What about the average user?

Most of the work will be done by the manufacturers of browsers, operating systems, and services. You can help in a simple way: keep your devices and apps up to date, use services with a good reputation for security, and don’t trust “quantum-secure” products without verifiable information about which standards they actually use.

Conclusion: Don’t panic, but don’t put it off either

Quantum computers have real potential in science and industry, but they are not yet capable of breaking modern encryption, and no one knows exactly when that will happen. It is precisely this uncertainty that is the reason why preparations are beginning now: data can be intercepted today, and migrating large systems takes years. The right response is not panic, but a plan.