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The Fit and the Pendulum Quantum Mechanics and New Clocks M. Crescimanno Department of Physics and Astronomy Youngstown State University & R. Walsworth, D. Phillips, Irina Novikova and Christine Wang Harvard -Smithsonian Center for Astrophysics
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$$$ : ONR, NASA, Research Corporation, Cluster Ohio Program, YSU PACER funds
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"No one can serve two masters; for a slave will either hate one and love the other or be devoted to the one and despise the other."
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IDEAL CLOCK Bright : need good SNR to "split" the line. Dark : period needs to be immune from environment. Based on regularity of periodic behavior must be:
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Gerard David "Rest on the Flight into Egypt" 1512(?)
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A Brief History of Time......Measurement Mercury Ion Stability 10 3-4 10 4-6 10 7-10 10 14 Size/Cost Rooms Table Quarter ?
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Why Small Atomic Clocks? " Cell Phone Repeaters " GPS System
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Rb Atomic Clock 6.8 GHz 87 Rb microwave cavity Optical table: lasers, optics and magnetic shields Q L = 15,000 split endplate design for double bulb mechanical tuning access for fiber optical detector (Source: D. Phillips)
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Level Scheme What the experimentalist knows... Level Scheme Simplified What the theorist thinks...
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Atomic Clock: Traditional Maser Good: Bad: Simple, Bright Light shifts, environment couplings large, bulky Microwave Cavity Shield Light RF Pickup
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Need to shine some dark on this clock... (Use interference) Fountain Clocks (Reduce time atoms spend in cavity) CPT Clock
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Coherent Population Trapped Clock = optical pumping to a superposition hyperfine ground states bc ac |a> |c> |b> ab Atomic population's dipole vanishes "Dark State" No microwave cavity Small Size Simple construction Low light readout
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CPT = Electromagnetically Induced Transparency Light Collisions,... RWA o1
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CPT = Electromagnetically Induced Transparency Static Solution (exact) Im(rho_01) = probe beam absorption Little spike of transparency in middle... Dispersion: Large index of refraction = slow- and stopped light
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EIT window CPT clock : lock to center of EIT window
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CPT clock : Elements 2 Lasers Shield Photodetector
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Schematic of "All-Optical" Atomic Clock cell oven solenoid shields bc ac |a> |c> |b> ab (Source: D. Phillips, R. Walsworth) isolator power level = +17 dBm freq=6.834 GHz x2 Multplier VCXO 12 GHz photodetector cell oven solenoid shields 6.84 GHz LO 3.42 GHz drive 3.42 GHz EOM DC feedback signal laser diode
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Why so good? " Environmental susceptibility (Data from I. Novikova) " Medium Term stability at the 10 12 Level
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Simulation vapor cell inputs: gas, pressure, laser power, beam diameter diffusion coefficient, line shifts, broadenings... bc ac |a> |c> |b> ab 3-level density matrix solver average over velocities, diffusion dv v output lineshapes calculations performed in C/GSL/IDL parameters chosen to match experimental conditions from literature and our measurements Detection
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Simulatio n Doppler effect + Motional Averaging (Lamb-Dicke) Analytic solution for steady state AC Stark Effect due to carrier Lockin detection modulation dependent effects - (EIT line asymmetry) Includes...
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Preliminary Comparisons So many knobs to twist ! DATA THEORY
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DATA THEORY Detuning Slope w1/w0 ~ 10 mHz/MHZ Slope is negative !
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Dependence on Modulation DATA THEORY
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Carrier Intensity Stark Effect DATA THEORY
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CONCLUSIONS: CPT clock may be promising Experiment and QO theory are converging QO theory informing design compromises
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