Scientists have demonstrated a new method that could allow quantum information to be safely backed up, overcoming one of the longest-standing limitations in quantum computing without violating the fundamental laws that govern quantum systems.
The research describes a way to encode the information contained in a qubit across multiple entangled systems, allowing the original quantum state to be recovered later without directly copying it.
If proven viable at scale, the approach could address a major obstacle in quantum computing: how to store and protect fragile quantum information without destroying it.
Why Copying Qubits Has Always Been a Problem
In classical computing, copying information is pretty straightforward. Files can be duplicated endlessly, backed up across servers, and restored when hardware fails.
Quantum computing, however, operates under very different constraints. Qubits can exist in superpositions and become entangled with one another, enabling powerful computational advantages, but also making them extremely sensitive to disturbance.
One of the most fundamental rules governing quantum information is the no-cloning theorem, a term which might conjure images of Dolly the sheep, although this doesn’t involve cloning in the biological sense. This theorem states that an unknown quantum state cannot be copied perfectly, and has long been seen as a roadblock for practical quantum systems, particularly when it comes to reliability and data protection.
Without the ability to copy qubits, familiar concepts like redundancy, backups, and recovery—cornerstones of modern computing infrastructure—simply don’t translate cleanly into the quantum world.
A Backup Without Breaking the Rules
The new approach, detailed by researchers who published their work in Physical Review Letters, doesn’t attempt to bypass quantum mechanics: instead, it works within it.
Rather than cloning a qubit outright, researchers encrypt the information contained in the quantum state across entangled systems, using techniques tied to quantum encryption and quantum information theory. Each encrypted share is unreadable on its own, but with a single-use quantum key, the original state can be reconstructed exactly one time. Once that key is used, it is destroyed, preventing further recovery.
Crucially, the quantum state is never duplicated in a classical sense. The no-cloning theorem remains intact, while redundancy becomes possible in a limited, carefully controlled way.
Why This Matters for Quantum Computing
Quantum computers are notoriously prone to errors caused by environmental noise, interference, and hardware instability. Even a single disruption can corrupt quantum information and halt a computation entirely, which is why researchers have spent years developing approaches to quantum error correction.
If quantum states can be backed up, however, it could help to enable distributed quantum storage, fault-tolerant architectures, and eventually quantum cloud infrastructure. In such systems, quantum information could be stored across multiple nodes and recovered if one fails, a concept closely tied to emerging quantum networks and distributed quantum communication.
Important Limits Still Apply
Despite some headlines suggesting qubits can now be freely copied, the researchers stress that this is not classical cloning in the quantum sense. The recovery process works only once, and the encrypted states cannot be measured or accessed without destroying the information they contain. In practical terms, this means the method allows for redundancy, but only under very specific conditions that remain tightly constrained by quantum mechanics.
This distinction is important because, for now, it underscores that the no-cloning theorem has yet to be overturned. However, the new approach carefully navigates around it, preserving the rule while still allowing a “bypass” that extracts useful functionality from quantum systems. The method relies on the same quantum properties that impose limits in the first place, particularly entanglement and the irreversible nature of measurement.
In that sense, the breakthrough reflects a broader theme seen across quantum physics, where progress often comes not from breaking physical laws, but from becoming a sort of quantum wolf in sheep’s clothing and finding clever ways to work within them. Many of the most promising advances in the field follow this same pattern, revealing unexpected flexibility inside what once appeared to be absolute constraints.
Looking Ahead
While the method remains largely theoretical, it represents a meaningful step toward making quantum computing more resilient. If it can be implemented reliably, quantum systems may eventually gain a form of backup and recovery once thought impossible.
As quantum technologies mature, solutions like this could play a key role in how future quantum computers, networks, and storage systems are designed, echoing broader trends seen across the rapidly advancing field of quantum computing.
As one of the study’s authors, Dr. Achim Kempf, explained in a statement, “This breakthrough will enable quantum cloud storage, like a quantum Dropbox or quantum Google Drive, that safely and securely stores the same quantum information on multiple servers.”
The team’s recent study, “Encrypted Qubits can be Cloned,” was published in Physical Review Letters.
Caleb Hanks is a freelance writer, musician, and audio engineer based in Asheville, North Carolina.