How to make quantum computers hackproof decoded

Scientists have built the first high-dimensional quantum cloning machine that can intercept a secure message, an advance that helped uncover clues to protect next-generation computers from hacking attacks.
Protecting traditional computer systems, which use zeros and ones, from hackers is not a perfect science.
In the complex world of quantum computing, where bits of information can simultaneously hold multiple states beyond zero and one, potential threats become even trickier to tackle.
"Our team has built the first high-dimensional quantum cloning machine capable of performing quantum hacking to intercept a secure quantum message," said Ebrahim Karimi, a professor at the University of Ottawa in Canada.

"Once we were able to analyse the results, we discovered some very important clues to help protect quantum computing networks against potential hacking threats," said Karimi.
Quantum systems were believed to provide perfectly secure data transmission because until now, attempts to copy the transmitted information resulted in an altered or deteriorated version of the original information, thereby defeating the purpose of the initial hack.

Traditional computing allows a hacker to simply copy and paste information and replicate it exactly, but this does not hold true in the quantum computing world, where attempts to copy quantum information - or qudits - result in what Karimi refers to as "bad" copies.

For the first time, the team was able to clone the photons that transmit information, namely the single carriers of light known as qubits, as well as quantum theory allows, meaning that the clones were almost exact replicas of the original information.
However, in addition to undermining what was previously thought to be a perfect way of securely transmitting information, the researchers' analyses revealed promising clues into how to protect against such hacking.
"What we found was that when larger amounts of quantum information are encoded on a single photon, the copies will get worse and hacking even simpler to detect," said Frederic Bouchard, doctoral student at University of Ottawa.

"We were also able to show that cloning attacks introduce specific, observable noises in a secure quantum communication channel," said Bouchard.
"Ensuring photons contain the largest amount of information possible and monitoring these noises in a secure channel should help strengthen quantum computing networks against potential hacking threats," he said.
The quantum hacking efforts could be used to study quantum communication systems, or more generally to study how quantum information travels across quantum computer networks.
The research was published in the journal Science Advances.