French scientists successfully built the Einstein box

From 1927, Albert Einstein once thought of a box to trap light. At that time, his idea was still a proposed fictional experiment to test the relationship between mass and energy.

Eighty years later, French physicists claim that they have formed the Einstein box: a 2.7cm-sized box that traps a photon to observe it from birth to death.

"You almost always see photons, such as you are seeing a lot of photons in front of a computer screen," said Jean-Michel Raimond at the French National Center for Scientific Research (CNRS). "You only see each photon once. But now we can analyze photons when they are still alive."

The physicists used to put self-light rays into the box with enough time to see the appearance, activity and dissolution of the photon.This box has a surface made of superconducting mirrors (Photo: Michel Brune)

The Einstein box consists of a cavity and partitions with super-reflective properties. Superconducting mirrors can trap a photon in a seventh of a second. In such a time, a free photon could move ten times the distance from the Earth to the Moon.

The usual way to count photons is for particles to collide with them to absorb their energy. But this way obviously destroys the photon. Therefore, what we need is a " transparent " counter. The French team published in the British Journal Nature , that they solved the problem by using a stream of rubidium atoms running through the box to trap photons. The electric fields of the photons slightly alter the energy levels of the atoms, but in this case, the structure of the energy levels does not allow the atoms to absorb the energy of the photon field.

When an atom enters the photon field, its electrons are slightly delayed. This delay is measured by modern atomic clock technology. Here, the electrons are like the " pendulum " of the pendulum clock.

In a Nature commentary, Ferdinand Schmidt-Kaler, a University of Ulm quantum physicist (Germany), called the achievements of French scientists an " experimental masterpiece ", creating application possibilities. for quantum computing, a frontline field of current technology research.

The experiment showed that "one stream of qubits (quantum information units) of atoms can be completely controlled by the qubit state of a trapped photon," Schmidt-Kaler said.

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