However scientists have discovered a way to create an interaction so strong that the phase of the photons is changed by 180 degrees. The breakthrough could help in the development of quantum computing, among other applications.
Photons communicate via glass fiber: The science
The scientists used a super-thin glass fiber coupled with a bottle-like light resonator, which allowed light to enter the resonator, move in circles and return to the glass fiber.
The system undergoes a dramatic change when a single rubidium atom is coupled to the resonator. The amount of light entering the resonator is severely restricted, and the oscillation phase of the photon can’t be inverted. However if two photons arrive at the same time, things are very different.
“The atom is an absorber which can be saturated,” said researcher Arno Rauschenbeutel in a press release. “A photon is absorbed by the atom for a short while and then released into the resonator. During that time, it cannot absorb any other photons. If two photons arrive simultaneously, only one can be absorbed, while the other can still be phased shifted.”
It is impossible to tell which of these photons has been absorbed and which one has passed. Under the terms of quantum mechanics both have been phase shifted by 180 degrees.
“That way, a maximally entangled photon state can be created,” said Rauschenbeutel. “Such states are required in all fields of quantum optics-in quantum teleportation, or for light-transistors which could potentially be used for quantum computing.”
Risks and benefits of quantum computing
Scientists have long dreamed of constructing a quantum computer, which would be thousands of times faster than existing ones.
However recent advances in the field have led to concerns that the very foundations of the security of the internet could crumble if they ever became a reality. The vast increase in speed offered by quantum computers would be enough to easily crack the “keys” to the internet, with consensus on an alternative form of security yet to be found.
More detailed information can be found in the journal Nature Photonics.
