Optimal phase sensitivity of atomic Ramsey interferometers with coherent spin states

Xiao-Jie Yi

Priyanka Sharma, Anand Kumar, Gaurav K. Shukla +1 more

Guangri Jin, Yong‐Chun Liu, Li You

We present a detailed analysis of phase sensitivity for a nonlinear Ramsey interferometer, which utilize effective mean-field interaction of a two-component Bose-Einstein condensate in phase accumulation. For large enough particle number N and small phase shift ϕ, analytical results of the Ramsey signal and the phase sensitivity are derived for a product coherent state |θ, 0〉. When collisional dephasing is absent, we confirm that the optimal sensitivity scales as 2/N 3/2 for polar angle of the initial state θ = π/4 or 3π/4. The best-sensitivity phase satisfies different transcendental equations, depending upon the initial state and the observable being measured after the phase accumulation. In the presence of the collisional dephasing, we show that the N −3/2-scaling rule of the sensitivity maintains with spin operators $\hat J_x$ and $\hat J_y$ measurements. A slightly better sensitivity is attainable for optimal coherent state with θ = π/6 or 5π/6.

Ralf Kohlhaas, Etienne Cantin, Andréa D Bertoldi +5 more

Luca Pezzè, Augusto Smerzi

We propose a hybrid quantum-classical atomic clock where the interrogation of atoms prepared in a spin-coherent (or weakly squeezed) state is used to feed back one or more highly spin-squeezed atomic states toward their optimal phase-sensitivity point. The hybrid clock overcomes the stability of a single Ramsey clock using coherent or optimal spin-squeezed states and reaches a Heisenberg-limited stability while avoiding nondestructive measurements. When optimized with respect to the total number of particles, the protocol surpasses the state-of-the-art proposals that use Greenberger-Horne-Zeilinger or NOON states. We compare analytical predictions with numerical simulations of clock operations, including correlated 1/f local oscillator noise.

Louis Pagot, Joel Gomes Baptista, Léo Rol +4 more