transition frequency

In the quantum world, particles sometimes behave like acrobats on invisible tightropes. An instanton field is a brief vortex that appears and vanishes in an instant. When a fermion (a particle like an electron) enters such a vortex, its energy does not stay put. Instead, it smoothly slides from one level to another, like a ball rolling down a hill.

Hydrogen is the simplest atom: one proton and one electron. You'd think there's nothing left to study. But it's precisely on hydrogen that physicists test the most delicate laws of the microcosm. The electron in an atom can occupy different energy levels, like steps on a ladder.

The light an atom emits is not just a flash. It carries an imprint of the atom's state at the moment of emission. Physicists took a superconducting qubit, an artificial atom the size of a microchip, and made it glow into an open waveguide, like a bulb in a long corridor.

Ahead of the bow shock that Earth creates in the solar wind, giant bubbles of rarefied gas sometimes appear. Inside them, particle density drops by factors, and electric fields start to tremble like a plucked string.

The hydrogen atom is like a tiny clock, ticking with a precision engineers can only dream of. When an electron jumps between orbits, it absorbs or emits light at a strictly defined frequency: that's the 'tick.' In the new work, physicists caught one such transition, between the 2S and 6P states, and measured its frequency with an…

The light an atom emits or absorbs is like a fingerprint: each element has its own pattern of lines. In an ytterbium ion (an atom that has lost one electron), researchers have found three new lines that were previously unused. These lines are very narrow, like thin slits in a fence that let you see far and clearly.

A virus approaches a cell like a key to a lock. But this lock is not ordinary: it vibrates, it trembles, and whether the key matches the rhythm of those tremors determines if the door opens. According to new research, this is exactly how recognition works between the coronavirus spike protein and the ACE2 receptor on the surface of human cells.

The helium atom is like a tiny solar system: electrons orbit the nucleus, but their orbits are governed by strict rules. Scientists have learned to observe these motions with incredible precision.

A beam of visible light enters a cloud of billions of rubidium atoms cooled to near absolute zero, and emerges on the other side already in the telecom range.

Quantum entanglement is like an invisible spring between particles — squeeze one, and the other twitches, no matter where it is. In the new work, physicists built a model of four spins (tiny magnetic arrows) in a chain, where the end spins are held by a local magnetic field.