Is it possible to see an atom with the naked eye without using an electron microscope? Although physics teaches that an atom measures barely a fraction of a nanometer, in 2018 physicist David Nadlinger, from the University of Oxford, amazed the scientific community by managing to photograph a single strontium atom suspended in a vacuum.
The milestone was not achieved by magnifying the atom's physical size, but by manipulating its interaction with light. Using an ion trap, two metal needles separated by barely two millimeters generated intense oscillating electric fields inside an extreme vacuum chamber. This field confined the positively charged strontium ion, keeping it motionless in the center of the device.
When illuminated by a laser tuned to the exact blue-violet frequency, the atom absorbed and re-emitted photons at a dizzying rate of millions of times per second. Using a standard digital camera configured with a long exposure through the laboratory window, that constant shower of light particles accumulated on the sensor, recording as a tiny bright dot between the two electrodes.
This achievement transcends aesthetics, as the control of individual particles is the cornerstone of:
- Quantum computing: Trapped ions are leading candidates to function as high-fidelity qubits.
- Ultra-precise metrology: It allows building optical clocks that would not lose a single second over the entire age of the universe.
The famous capture demonstrated that the barrier between the mysterious quantum realm and macroscopic optical perception can be crossed with technological ingenuity.
Source: University of Oxford / EPSRC Science Photography Competition (2018)
