Longitudinal Spectroscopy of 88Sr in a Moving Optical Lattice for Zero-Dead-Time Optical Lattice Clock

Optical lattice clocks that interrogates N atoms for an interrogation time T can, in principle, reach the quantum-projection-noise (QPN) instability σ_y (τ)∼1/(πν_0 T√Nτ), with ν_0 the clock frequency and τ the averaging time. In practice, however, dead time between preparation and readout aliases the local-oscillator (LO) frequency noise (Dick effect [1]), so the achievable instability is set by the LO noise spectrum and the duty cycle rather than by the QPN limit. This motivates zero-dead-time (ZDT) operation, which removes aliasing by maintaining continuous interrogation. Here we report Fourier-limited Rabi spectroscopy using longitudinal excitation [2] as a step toward ZDT operation of a strontium optical lattice clock, where the clock laser propagates along the lattice axis.