The field · sensing
Quantum sensing
Not computing — measuring. Sensing uses the same fragility that makes qubits hard to compute with (they respond to everything) as the signal. It is the branch of quantum technology with commercial products now, and the clocks below are the most precise instruments humans have built.
- Verified — published result
- Vendor-reported result
- Projection — roadmap target
- Opinion — named, dated
- Estimate — with caveats
- Contested — disputed in the record
- Preprint — not yet peer-reviewed
Records and readiness
An optical clock with 8.1 × 10⁻¹⁹ systematic uncertainty
Verified — published resultAeppli, Kim, Warfield, Safronova and Ye (JILA) reported a strontium optical lattice clock with a total systematic uncertainty of 8.1 × 10⁻¹⁹ in fractional frequency — stated as the lowest of any clock to date — by controlling the black-body radiation shift and second-order Zeeman coefficient. Clocks at this level resolve centimetre-scale height differences through gravitational redshift.
Two-minute atomic coherence; instability 1.5 × 10⁻¹⁸ at one second
Preprint — not yet peer-reviewedKim, Aeppli, Warfield, Chu, Rey and Ye reported a ⁸⁷Sr Wannier-Stark lattice clock with coherence of 118(9) s at reduced density — approaching the spontaneous-emission limit — and fractional instability of 1.5 × 10⁻¹⁸ at 1 s of averaging. Stability at one second is what makes such precision usable rather than merely attainable. A preprint at the time of checking.
Maturity by modality: clocks shipping, gravimeters in trials
Estimate — with caveatsAn industry guide places atomic clocks as the most commercially mature quantum-sensing modality (technology readiness 7–8, field-deployed products) with quantum gravimeters at readiness 5–6 in pre-commercial trials, and projects the sensor market at $1.5–2.0 billion by 2030. An aggregator's assessment, not a measurement — treat the readiness levels as a sketch and the market figure as a forecast.