Unlike classical encryption, which relies on mathematical algorithms, quantum encryption assures security based on physical principles. Detection of espionage or interference is guaranteed by unavoidable alteration of the quantum states involved.

Comparisons between the two systems yield impressive results. Classical supercomputers would currently take thousands of years to break strong encryption, but it will be possible to decipher the same codes in seconds with sufficiently powerful quantum computers.

"This highlights the urgent need to develop and implement quantum security protocols that are immune to such capabilities," said Paulo Henrique Dias Ferreira, a researcher in the Department of Physics at the Federal University of São Carlos (UFSCar) in São Paulo state, Brazil.

During a postdoctoral internship at the Polytechnic University of Milan in Italy, Ferreira worked with the group led by Professor Roberto Osellame and contributed significantly to the creation and characterization of entangled four-photon GHZ (Greenberg-Horne-Zeilinger) states on a . The research is published in the journal npj Quantum Information.

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