Architecture of the Cooling Laser

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Table of contents

Introduction 
0.1 Optical Atomic Clocks
0.1.1 Ion-based optical clocks
0.1.2 Optical lattice clocks
0.1.3 Current and prospective applications of optical frequency standards
0.1.4 Context and objectives of my PhD work
0.2 The Mercury Atom: a Short Overview
0.3 Mercury Level Structure: the Key to a Highly Accurate Frequency Standard
0.4 Thesis Overview
1 A Mercury Optical Lattice Clock 
1.1 Overview of the Experimental Setup
1.2 Cooling of Mercury Atoms in a Magneto-Optical Trap
1.2.1 The cooling-laser system
1.2.2 3D-MOT of 199Hg
1.2.3 Vapor pressure and MOT lifetime
1.2.4 Pre-cooling with a 2D-MOT
1.3 Trapping in a 1D “Magic” Optical Lattice
1.3.1 The trapping laser system
1.3.2 Locking scheme for the lattice light
1.3.3 A build-up cavity for a deeper trap
1.3.4 Absolute frequency calibration with a frequency comb
1.3.5 Lifetime of the atoms in the lattice
1.4 An Ultra-Stable Laser System for Coherent Atomic Interrogation
1.4.1 Fabry-Perot cavity for laser stabilization
1.4.2 Ultra-stable laser setup
1.4.3 Laser noise and frequency doubling
1.5 Fluorescence Detection
2 A New Laser System for Cooling Mercury Atoms 
2.1 Requirements
2.1.1 Spectral purity
2.1.2 Laser power
2.2 Architecture of the Cooling Laser
2.2.1 External-Cavity Diode Laser
2.2.2 Laser amplifier and single stage doubling to 507 nm
2.2.3 Frequency doubling to 254 nm
2.2.4 Locking to the cooling transition via saturated-absorption spectroscopy
2.3 A Second System for the 2D-MOT
2.3.1 Frequency locking of the two seed lasers for 2DMOT operation
3 High-Resolution Spectroscopy in an Optical Lattice Trap 
3.1 Theory: Spectroscopy in a 1D Optical Lattice
3.1.1 Clock spectroscopy in the Lamb-Dicke regime
3.1.2 Structure of the clock transition
3.1.3 Rabi and Ramsey spectroscopy
3.2 Experimental Spectroscopic Signals and Their Interpretation
3.2.1 Magnetic field zeroing using clock spectroscopy measurements
3.2.2 Carrier spectroscopy of the two Zeeman sublevels
3.2.3 Control of atomic noise: implementing a normalized detection
3.2.4 Towards improved stability: high-resolution Rabi and Ramsey spectroscopy
3.2.5 Rabi flopping and excitation inhomogeneities
3.3 Estimation of the Trap Depth with Transverse Sideband Spectroscopy
3.3.1 Spectroscopy with a misaligned probe beam
3.3.2 Estimation of the trap depth
3.4 Studies of Parametric Excitation in the Trap
3.4.1 Trap depth estimation
3.4.2 Atomic temperature filtering
4 Clock Operation and Short-Term Stability Optimization 
4.1 Locking to the Atomic Resonance
4.2 Allan Deviation and Clock Stability
4.3 Fundamental Sources of Noise
4.3.1 Quantum projection noise
4.3.2 The Dick effect
4.3.3 Optimization of clock stability
4.4 Study of the Detection Noise
4.5 Estimating the Mercury Clock Stability Without Referencing
to a Second Optical Clock
4.5.1 The atoms against the ultrastable cavity
4.5.2 Stability for systematics evaluation
4.6 Stability of a Two-Clocks Comparison: Correlated Interrogation
4.6.1 Principle of correlated interrogation
4.6.2 Transfer of spectral purity via the optical frequency comb
4.6.3 Correlated interrogation – experiments
5 Ascertaining the Mercury Clock Uncertainty Beyond the SI Second Accuracy 
5.1 Clock Accuracy
5.1.1 Digital lock-in technique for studying systematics
5.2 Collisional Shift
5.2.1 Theoretical introduction
5.2.2 Experimental results
5.3 Lattice AC Stark-Shift
5.3.1 Linear shift
5.3.2 Vector shift
5.3.3 Higher order terms
5.4 Zeeman Shift
5.4.1 Linear Zeeman effect
5.4.2 Quadratic Zeeman effect
5.5 Blackbody Radiation Shift
5.6 Measurement of the Phase Chirp Introduced by the Pulsing of the Clock Acousto-Optics Modulator
5.6.1 Digital I/Q demodulation for phase estimation
5.6.2 Results and shift estimation
5.7 Other Shifts
5.7.1 Background gas collisions
5.8 Final Uncertainty Budget
6 Frequency Ratio Measurements for Fundamental Physics and Metrology 
6.1 Purpose of Frequency Ratios Measurements
6.1.1 Redefinition of the SI second
6.1.2 Time variation of fundamental constants
6.2 Detailed Experimental Scheme
6.3 Comparison With Microwave Frequency Standards
6.3.1 Hg/Cs frequency ratio
6.3.2 Hg/Rb frequency ratio
6.3.3 Gravitational redshift estimation and correction
6.4 Comparison With a Strontium Optical Lattice Clock
6.5 Measurement of Frequency Ratios via European Fiber Network
6.6 Long-Term Monitoring and Fundamental Constants