Enhanced Light Emission Improves Atom Readout
Future atom-based quantum technologies will require fast and reliable ways to read out an atom’s quantum state. But technical limitations have meant that current methods are often too slow, too error prone, or both. Now Jian Wang and his colleagues at the University of Science and Technology of China have demonstrated a readout technique that achieves unprecedented speed and accuracy [1]. The approach’s key innovation is a technique for boosting the atom’s rate of photon emission.
Typically, atom readout involves shining laser light on a trapped atom that can be in one of two quantum states. If the atom is in the “dark” state, it won’t respond to the light. But if it is in the “bright” state, it will absorb the light and then emit photons. A photon detector can then be used to identify the atom’s state. The speed and accuracy of this readout are limited by the number of photons the atom emits in a given time when it is in the bright state.
Wang and his colleagues placed a trapped atom in the optical version of an echo chamber: a so-called Fabry-Pérot microcavity. This structure’s resonant frequency was tuned to match the frequency of the atom’s emitted photons, which boosted the atom’s emission rate through a phenomenon known as the Purcell effect. The researchers detected as many as 18 million photons per second, compared with only up to a few million in previous experiments. With this improvement, the team attained a record readout accuracy (99.985% in 9 microseconds) and a record readout speed (just 200 nanoseconds for an accuracy of 99.1%).
–Ryan Wilkinson
Ryan Wilkinson is a Corresponding Editor for Physics Magazine based in Durham, UK.
References
- J. Wang et al., “Ultrafast high-fidelity state readout of single neutral atom,” Phys. Rev. Lett. 134, 240802 (2025).