Quantum Metrology Optical Atomic Clocks & Many-Body Physics

Transcription

1 Quantum Metrology Optical Atomic Clocks & Many-Body Physics Jun Ye JILA, National Institute of Standards & Technology and University of Colorado APS 4CS Fall 2011 meeting, Tucson, Oct. 22, 2011 Many-body quantum systems Optical atomic clocks

2 Optical atomic clocks Oscillator Ultrastable laser Sr atoms Counter optical comb optical frequency counter

3 The age of atomic clocks - Chasing the SPEED! Faster oscillations More cycles Smaller errors Light ripples: cycles per second, & we count every one Precision: ± 1 Earth bacteria Sun

4 Testing fundamental laws of nature Are the laws of nature the same for the early universe and the present? LISA 4

5 An interacting many-body quantum system U U U ~ 1 Hz ~ 50 x K

6 First, a precise optical field - Stable optical cavity Cavity length 1 m : fits 10 6 optical waves (10-6 ) Finesse 10 5 : error amplified by 10 5 (10-11 ) Division of a cycle: 10 4 (10-15 )

7 Long-term optical coherence (>1 s) Ludlow et al., Opt. Lett. 32, 641 (2007). Cavity 2 Cavity 1 Laser 2 Laser 1 (a. u.) Linea ar Signal Optical linewidth: 250 mhz Beat between two independent lasers Hz

8 A rainbow spectrum with precision Hall and Hänsch, 2005 Nobel Prize Optical frequency comb Cundiff and Ye, Rev. Mod. Phys. 75, 325 (2003). l amplitude signa (ar rb. units) Radio freq. Radio frequency Optical Light freq :1 Counting Reduction the Gearlight ripple Light time (s ) Optical coherence time > 1 s (<10-15 ), anywhere in the visible Schibli et al., Nature Photonics 2, 355 (2008).

9 Strontium

10 Alkaline earth A tale of Twin Electrons JILA, Tokyo, Paris, NIST, PTB, Florence, NICT, NPL, NIM, NRC Science 314, 1430 (2006). PRL 98, (2007). Science 319, 1805 (2008). 1 P nm (~ 5 ns) 3 P 0 Metastable state quality factor 698 nm 1 S 0 (~ 150 s) Q > 10 17

11 Stop the moving atom atom photons δ = -800 khz g δ = khz δ = khz 1 billionth (10-9 ) of room temperature δ = khz 5.6 mm

12 Trapping atom with light 2> λ 3 1 P 0 Ye, Kimble, & Katori, Science 320, 1734 (2008). 1> 698 nm λ 2 1 S 0 λ magic

13 Atomic recoil 3 P 0 No recoils 1 S 0 photon

14 Atomic Chain Optical lattice Ludlow et al., Phys. Rev. Lett. 96, (2006). Clock probe S/N ~ N 1/2 698 nm (~ 150 s) 1 S 0 3 P 0 N atoms ω trap ωtrap >> Photon recoil, clock linewidth No Doppler, No Recoil, No Stark shift

15 Coherent spectroscopy Q ~ 5 x April, 2011 Sr linewidth: 0.8 Hz Instability ~ 5 x / τ Reaching the quantum projection noise?

16 JILA Sr atomic clock Ludlow et al., Science 319, 1805 (2008) Frequency shift by atomic collision is a dominant contribution 10, 000, 000, 000, 000, 000 ± 1 (10-16 ) Sr Yb standards tota al devi iation Definition of SI SECOND Ludlow / Time & Freq time (s)

17 Interactions between identical Fermions (1) Particles behave like waves (T -> 0) (2) Angular momentum is quantized s p d 0 1ħ 2ħ (3) Quantum statistics matter ψ 0 ψ 1 ψ 1 ψ 0 Fermions L = 1, p-wave collisions

18 Indistinguishability zˆ W yˆ V 1 xˆ U Campbell et al., l Science 324, 360 (2009). Optical excitation Bloch sphere Ω / Ω Clock frequency shift: 5 x ± 0.8 x s-wave collisions now allowed, amplitude depends on inhomogeneous excitation.

19 Two atoms two modes Singlet State Interaction U a eg g e s = - 2 n 1 n 2 + n 2 n 1 2 n 2 n 1 + n 1 n 2 - n 2 + Til Triplet States No s-wave collisions t t = = n 1 2 n n n n 1 2 U = 0 t = n1 n2 - n2 n 1 n 2 - n 2 n 1 2

20 Suppression via Strong Interaction U (ω x ω y ω z ) 1/2 1D Lattice Weakly Interacting Strongly Interacting 2D Lattice Blockade - like suppression Δν U ΔΩ Ω 2 2 Δν ΔΩ U 2

21 Collision shift suppressed: 5 x x Swallows et al., Science 331, 1043 (2011). ) ft ( ) uency shif Fractional frequ Atomic interaction energy (Hz)

22 z ˆ W Competition between Ω and U yˆ V x ˆ U (1) Ω >> U mean-field shift Ω Rabi frequency U (2) Ω < U spin spectrum & excitation gaps Interaction energy

23 1D lattice, low density 80 khz lattice, 3.8 uk, 3 atoms per site, 1 s clock probe Ω: 0.5 Hz 0.6 Exc cited sta ate fract ion mhz Hz Frequency (Hz)

24 1D lattice, high density Bishof et al., arxiv: (2011). 80 khz lattice, 3.8 uk, 30 atoms per site, 1 s clock probe ed state fraction Excit Hz! Frequency (Hz) Frequency (Hz) 0

25 Optical lattice a many-body quantum system Science 331, 1043 (2011); Phys. Rev. Lett. 106, (2011). Engineered quantum states eliminating motional effects Separation of internal and external degrees of freedom Isolation from environment Long coherence times Large atom numbers to increase signal and accuracy 3D 1D Lattice 2D Lattice

26 J. Ye M. Swallows S. Blatt JY M. Martin T. Nicholson M. Bishof G. Campbell S i (2006) S i (2008) Science 314, 1430 (2006); Science 319, 1805 (2008); Science 320, 1734 (2008); Science 324, 360 (2009); Science 331, 1043 (2011).

27 M. Swallows M. Bishof M. Martin T. Nicholson B. Bloom J. Williams Special thanks Ana Maria Rey (theory) S. Blatt (Harvard) A. Ludlow (NIST) Y. Lin (NIM, Beijing) G. Campbell (U. Maryland) M. Boyd (AO Sense) J. Thomsen (U. Copenhagen) T. Zelevinsky (Columbia U.) T. Zanon (Univ. Paris 13) S. Foreman (Stanford U.) T. Ido (Tokyo NICT) T. Loftus (U. Washington) X. Xu (ECNU) X. Huang (WIPM)