Physics of precision measurement and metrology: optical-lattice atomic clocks (Sr-87, Yb-171, Hg, Al+ ion clocks) at 10⁻¹⁸-level instability, Cs fountain definition of the SI second, frequency-comb absolute optical-frequency linkage, atom…
precision-measurement-physics
Optical-lattice clock at the magic wavelength: cancels AC Stark for |g⟩ and |e⟩
Optical-lattice clocks (Katori 2003 proposal; Takamoto-Hong-Higashi-Katori 2005 demonstration) trap neutral atoms in a 3D standing-wave…
Quantum projection noise (SQL): σ_δν ≥ 1/(2π·T·√(N·T_tot/T))
Bollinger-Itano-Wineland-Heinzen (1996) quantum projection noise (QPN) / standard quantum limit (SQL): for an ensemble of N uncorrelated…
Black-body radiation shift: Δν_BBR ∝ −⟨α⟩·T⁴ (Stark from thermal photons)
At non-zero ambient temperature, thermal black-body photons exert an AC Stark shift on the atomic clock transition, Δν_BBR =…
Ramsey fringe: P(δ) = cos²(δT/2) — Ramsey 1950 separated-oscillatory-field
Ramsey 1950 separated-oscillatory-field method: two π/2 pulses of duration τ_p ≪ T separated by free-evolution time T produce an…
Mach-Zehnder atom interferometer: Δφ = k_eff · g · T² (Kasevich-Chu gravimeter)
Kasevich-Chu 1991 Mach-Zehnder atom-interferometric gravimeter: three stimulated-Raman pulses (π/2-π-π/2) separated by free-fall time T…
Allan variance of white frequency noise: σ²_y(τ) = h₀/(2τ) (τ^{−1} scaling)
Allan 1966 two-sample variance as the canonical frequency-stability estimator: σ²_y(τ) = ½⟨(y̅_{n+1} − y̅_n)²⟩, averaging…