Quantum computing stores and processes information in qubits, which can be implemented in individual electrons, photons, atoms, ions or tiny electrical currents.
Universities, industry and governments worldwide are investing heavily in technologies to control qubits and scale them into large, reliable quantum computers that could support applications in cybersecurity, materials science, medical research and complex optimization.
"This breakthrough will enable quantum cloud storage, like a quantum Dropbox, a quantum Google Drive or a quantum STACKIT, that safely and securely stores the same quantum information on multiple servers, as a redundant and encrypted backup," said Dr. Achim Kempf, the Dieter Schwarz Chair for Physics of Information and AI in the Department of Applied Mathematics at Waterloo.
Kempf described the work as an important step toward building quantum computing infrastructure while working within the constraint of the no-cloning theorem, which states that quantum information cannot be copied directly because of the delicate way quantum states encode data.
Kempf, who is also an associate at the Institute for Quantum Computing at Waterloo and an associate member of the Perimeter Institute, likened quantum information to splitting a password: if one person has the first half and another the second, neither can use it alone, but together they recover the valuable password.
In a similar way, qubits can share information collectively, and the amount of accessible information grows as more qubits are combined.
A single qubit holds limited information on its own, but when qubits are linked, they can store a large amount of information that becomes accessible only when the system is treated as a whole, a property known as quantum entanglement.
Kempf noted that 100 qubits can share information in 2^100 ways simultaneously, an amount of entangled information that exceeds what all current classical computers could store.
Despite this potential, the no-cloning theorem constrains routine practices from classical computing, such as copying data for sharing and creating backups, because there is no simple copy-and-paste operation for quantum states.
"We have found a workaround for the no-cloning theorem of quantum information," explains Dr. Koji Yamaguchi, who co-discovered the new method with Kempf while working as a post-doctoral researcher in Kempf's lab and who is now a research assistant professor at Kyushu University.
"It turns out that if we encrypt the quantum information as we copy it, we can make as many copies as we like. This method is able to bypass the no-cloning theorem because after one picks and decrypts one of the encrypted copies, the decryption key automatically expires, that is the decryption key is a one-time-use key. But even a one-time key enables important applications, such as redundant and encrypted quantum cloud services".
The protocol therefore enables many encrypted instances of the same quantum information to be distributed and stored, while ensuring that only one copy can be decrypted in practice because the key can only be used once.
The research, titled "Encrypted Qubits can be Cloned," was published in Physical Review Letters and presents a new approach for quantum networking and cloud-based quantum computing architectures that require secure, redundant quantum data storage.
Research Report: Encrypted Qubits can be Cloned
Related Links
University of Waterloo
Understanding Time and Space
| Subscribe Free To Our Daily Newsletters |
| Subscribe Free To Our Daily Newsletters |
