Scientists in Japan claim laser-based quantum internet breakthrough

Quantum internet technology would make 100 per cent secure internet communications possible

Scientists at Osaka University claim to have made a breakthrough in the development of quantum internet communications using lasers.

The researchers said that their experiments demonstrate that it is possible to translate "the information encoded in the circular polarisation of a laser beam" into the spin state of an electron caught in a quantum dot.

The results, they added, could encourage further research towards the development of quantum internet, eventually making it possible to quickly and securely send and receive information in a quantum manner.

Applying laser light allowed scientists to read the state of the electron, which enabled them to confirm that the electron state was in the correct spin state

The internet today was designed less for security and more for robustness. Quantum internet technologies, however, would change that by exploiting the main features of quantum physics, such as quantum entanglement.

Quantum entanglement enables particles with two different quantum states to share a much closer relationship. If two particles are entangled, then the state of one particle can be known by measuring the state of the other.

In the current study, the researchers used laser light to transmit quantum information to a quantum dot by altering the spin state of a single electron trapped in the quantum dot.

According to the scientists, angular momentum of electrons can be flipped when they absorb circularly polarised laser light.

On the tiny quantum dot, there is only enough space for the electron to pass the so-called Pauli spin blockade if it has the correct spin

Applying laser light allowed scientists to read the state of the electron, which enabled them to confirm that the electron state was in the correct spin state. The readout method used by the team was based on Pauli exclusion principle, in which two electrons are not allowed to occupy the same state.

"On the tiny quantum dot, there is only enough space for the electron to pass the so-called Pauli spin blockade if it has the correct spin," said first author Takafumi Fujita.

According to senior author Akira Oiwa, the transfer of superposition (entangled) states allows for completely secure quantum key distribution.

"This is because any attempt to intercept the signal automatically destroys the 'superposition', making it impossible to listen in without being detected," Oiwa added.

The detailed findings of the study are published in journal Nature Communications.

Any attempt to intercept the signal automatically destroys the 'superposition', making it impossible to listen in without being detected

Such developments in quantum communications are partly driven by state security concerns. The US Los Alamos National Laboratory has been experimenting with quantum communications for some time, while researchers in China have developed similar technology for satellite (and, potentially, space) communications, as well as a fibre network connecting four cities.

And in April, a team of researchers in Australia and Singapore claimed a breakthrough in quantum key distribution.

They claimed to have developed the prototype of a quantum device capable of generating all possible futures in a simultaneous quantum superposition. The researchers said that their initial prototype can represent up to 16 simultaneous futures.

In March, researchers at the University of Innsbrück in Austria said that they had conducted an experiment that proved that multiple versions of reality can exist simultaneously at the quantum level. That idea was first postulated in 1961 by Eugene Wigner, the Nobel Prize-winning physicist.

Wigner's experiment, which involved two individuals observing a single photon at the same time, proposed that it was possible that two individuals observe different states of the photon at the same time, yet their observations would be correct.