# Rydberg-atom microwave sensor at Warsaw retains 3× more Fisher information in lab test

- Published: 2026-11-15 05:09 UTC
- Section: Digital & Computing › Quantum technology
- Tags: Rydberg atoms, quantum metrology, microwave field sensing, Fisher information, detection loss, premeasurement processing, atomic ensemble, University of Warsaw, dipolar interactions, single-shot precision
- URL: https://realtech.media/news/rt-a25633e4b31f13e29423d765_rydberg_atom_microwave/

**In a laboratory experiment, University of Warsaw researchers used interactions between Rydberg atoms to cut information loss at readout; single-shot precision was 217 μV/cm.**

![Rydberg-atom microwave sensor at Warsaw retains 3× more Fisher information in lab test](https://realtech.media/media/2026/11/d59c01df91cc0a90.webp)
*scinexx*

A team led by Michał Parniak at the University of Warsaw has demonstrated a microwave sensor based on Rydberg atoms that keeps more measurement information despite losses at the detection stage, according to a paper on nature.com [1]. The experiment used an ensemble of about 100 million ultracold rubidium-87 atoms. For a single 160-ns microwave pulse, the sensor reached a single-shot precision of (217 ± 8) μV/cm [1].

## Sensor and the readout problem

Rydberg atoms have large dipole moments, so they respond strongly to external electric fields, and they can also be used for quantum information processing [1]. In the setup, light was first stored in the atomic ensemble as collective excitations. A short microwave pulse then acted on these excited states, after which the stored signal was converted back into light and read out.

Many signals are lost at this readout step, so high atomic sensitivity alone does not guarantee a low-loss measurement. Experimental loss at detection remains one of the key obstacles to a quantum advantage in practical scenarios, the authors note [1].

## Interaction protocol and Fisher information

Before readout, the team let the Rydberg excitations interact through inter-atomic dipolar interactions. The protocol is, counterintuitively, based on introducing an additional non-linear, lossy quantum channel [1]. The interactions cause losses themselves, but they change the quantum state so that later detection losses destroy less information. The extra step therefore works as protection applied in advance, not as a correction of data already lost. The authors describe this as premeasurement processing, which had been used in other sensing experiments but not demonstrated in Rydberg atomic systems [1].

The information content of a measurement is described by Fisher information, which sets how small the uncertainty in estimating the field can become. With the protocol, the authors report a threefold enhancement of Fisher information [1]. The normalized value was 3.0 ± 0.3 relative to a reference method without the additional processing. This does not mean the field strength was determined three times more precisely.

According to the authors, the approach relies on interactions intrinsic to the sensor and does not require a general-purpose quantum computer [1].

## Sources

1. [nature.com](https://www.nature.com/articles/s41467-026-76016-2)
2. [scinexx](https://www.scinexx.de/news/physik/quantensensor-bewahrt-dank-wechselwirkender-atome-mehr-messinformation)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-a25633e4b31f13e29423d765_rydberg_atom_microwave/