Quantum Teleportation Beyond Qubits
“Qutrit” Experiments Are a First in Quantum Teleportation
Excerpts and salient points ~
+ “Teleportation” also conjures visions of faster-than-light communication, but that picture is wrong, too. If Alice wants to send Bob a message via quantum teleportation, she has to accompany it with classical information transported via photons—at the speed of light but no faster. So what good is it?
Some researchers are less convinced, though. Akira Furusawa, a physicist at the University of Tokyo, says that the method used by the two teams is ill-suited for practical applications because it is slow and inefficient. The researchers acknowledge the criticism but defend their results as a work in progress.
+ Oddly enough, quantum teleportation may also have important utility for secure communications in the future, and much of the research is funded with cybersecurity applications in mind. In 2017 Pan, Zeilinger and their colleagues used China’s Micius satellite to perform the world’s longest communication experiment, across 7,600 kilometers. Two photons—each acting as a qubit—were beamed to Vienna and China. By taking information about the state of the photons, the researchers in each location were able to effectively construct an unhackable password, which they used to conduct a secure video call. The technique acts like a wax seal on a letter: any eavesdropping would interfere and leave a detectable mark.
+ Despite mild sniping, the rivalry between the groups remains relatively friendly, even though provenance for the first quantum teleportation of a qutrit hangs in the balance. Both teams agree that each has teleported a qutrit, and they both have plans to go beyond qutrits: to four level systems—ququarts—or even higher.
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