Download presentation
Presentation is loading. Please wait.
1
Quantum Chaos and Atom Optics: from Experiments to Number Theory Italo Guarneri, Laura Rebuzzini, Sandro Wimberger and S.F. Advice and comments: M.V. Berry, Y. Gefen, M. Raizen, W. Phillips Experiments: M. d’Arcy, G. Summy, M. Oberthaler, R. Godun, Z.Y. Ma Collaborators: K. Burnett, A. Buchleitner, S.A. Gardiner, T. Oliker, M. Sheinman, R. Hihinishvili, A. Iomin
2
Quantum Chaos Atom Optics Kicked Rotor Classical Diffusion (1979 ) Quantum Deviations from classical behavior Anderson localization (1958,1982) Observation of Anderson localization for laser cooled Cs atoms (Raizen, 1995) Effects of gravity, Oxford 1999 New resonance Fictitious Classical mechanics Far from the classical limit (2002) Quantum nonlinear resonance Short wavelength perturbation
4
Experiment R.M. Godun, M.B.d’Arcy, M.K. Oberthaler, G.S. Summy and K. Burnett, Phys. Rev. A 62, 013411 (2000), Phys. Rev. Lett. 83, 4447 (1999) Related experiments by M. Raizen and coworkers 1. Laser cooling of Cs Atoms 2. Driving Electric fielddipole potential On center of mass 3. Detection of momentum distribution
5
relative to free fall any structure? =momentum Accelerator mode What is this mode? Why is it stable? What is the decay mechanism and the decay rate? Any other modes of this type? How general?? Experimental results
6
Kicked Rotor Model Dimensionless units
7
Classical Motion Standard Map Assume Accelerated, also vicinity accelerated Robust, holds also for vicinity of kick
8
For typical kick Effectively random Diffusion in For values of Where acceleration, it dominates NonlinearityAccelerator modes robust
9
Classical Motion Standard Map For typical Effectively random Diffusion in for integer Diffusion Acceleration for examplesome and vicinity accelerated
10
Quantum Evolution operator rational Quantum resonance irrational pseudorandom Anderson localization like for 1D solids with disorder Anderson localization
11
Quantum classical quantum Eigenstates of Exponentially localized Anderson localization like for 1D solids with disorder rationalQuantum resonance Simple resonances: Talbot time irrational pseudorandom
12
Kicked Particle rotor Classical-similar to rotor Quantum :Not quantized periodictransitions fractional part of (quasimomentum ) CONSERVED rational, resonance only for few values of classical quantum Anderson localization irrational
13
kicked rotor kicked particle typical diffusion in acceleration integer arbitrary typical Localization in rational resonances resonances only for few initial conditions classical quantum
14
F.L. Moore, J.C. Robinson, C.F. Bharucha, B. Sundaram and M.G. Raizen, PRL 75, 4598 (1995) momentum (momentum) 2 <
15
Effect of Gravity on Kicked Atoms Quantum accelerator modes A short wavelength perturbation superimposed on long wavelength behavior
16
Experiment-kicked atoms in presence of gravity dimensionless units in experiment NOT periodicquasimomentum NOT conserved
17
NOT periodicquasimomentum NOT conserved gauge transformation to restore periodicity integer introduce fictitious classical limit whereplays the role of
18
Gauge Transformation same classical equation for Formomentum relative to free fall quasimomentumconserved
19
Quantum Evolution “momentum” up to terms independent of operators but depending on
20
“momentum” quantization effective Planck’s constant dequantization Fictitious classical mechanics useful fornear resonance destroys localization dynamics of a kicked system whereplays the role of meaningful “classical limit”
21
-classical dynamics motion on torus change variables
22
Accelerator modes motion on torus Solve for stable classical periodic orbits follow wave packets in islands of stability quantum accelerator mode stable -classical periodic orbit period 1 (fixed points): solution requires choice ofand accelerator mode
24
Color --- Husimi (coarse grained Wigner) -classicsblack
25
Color-quantum Lines classical
26
relative to free fall any structure? =momentum Accelerator mode What is this mode? Why is it stable? What is the decay mechanism and the decay rate? Any other modes of this type? How general?? Experimental results
27
Color-quantum Lines classical
28
decay rate transient decay mode
29
Accelerator mode spectroscopy period fixed point Higher accelerator modes: (period, jump in momentum) observed in experiments motion on torus map: as Farey approximants of gravity in some units Acceleration proportional to difference from rational
30
-classics
31
color-quantum black- classical experiment
33
Farey Rule
34
Boundary of existence of periodic orbits Boundary of stability width of tongue “size” of tongue decreases with Farey hierarchy natural
35
After 30 kicks
38
Summary of results 1. Fictitious classical mechanics to describe quantum resonances takes into account quantum symmetries: conservation of quasimomentum and 2. Accelerator mode spectroscopy and the Farey hierarchy
39
General Context Accelerator mode (b) Measurement of 1.How general are the robust resonances? 2.Experimental preparations of coherent superpositions 3.Manipulation of resonances and interferometry (a) Narrow coherent momentum distribution 4. Tuning “gravity” 5. Resonaces and number theory? 6. Improved resolution of ?? 7. Quantum ratchets??
40
Resonances NO gravity
41
Momentum distribution at resonance at resonance using up to constants Exactly solvable, typically localized states. resonances and ballistic motion for specific quasimomentum for example Effectively ballistic motion for a timefor an interval of size in
42
M.F. Andersen, A. Varizi, M.B. d’Arcy, J.M. Grossman, K. Helmerson, W.D. Phillips + simulationtheory experiment NIST2005
43
resonance
44
Dynamics near resonance Quantum resonanceClassical resonance What is? at resonance But averaged over a wide range of quasimomentum mod Average overand over scaling,dependence only via
45
M.F. Andersen, A. Varizi, M.B. d’Arcy, J.M. Grossman, K. Helmerson, W.D. Phillips 1 NIST2005 scaling,dependence only via
46
Averaging over Qusimomentum
47
-classical quantum
48
Experiment on Cesium Atoms (Wimberger, Sadgrove, Parkins, Leonhardt, PRA 71, 053404 (2005))
49
Experiment on Cesium Atoms (Wimberger,Sadgrove, Parkins, Leonhardt, PRA 71, 053404 (2005))
50
Summary of results 1.Fictitious classical mechanics to describe quantum resonances takes into account quantum symmetries: conservation of quasimomentum and 2. -classical description of quantum resonances and their vicinity, relation to classical resonances 3. Scaling theory for vicinity of resonance (averaged and not averaged over Quasimomentum) 4. Narrow as peaks near resonance ( Found to hold also for higher order resonances) 5. Momentum distribution functions at resonance 6. Comparison with experiments (general characteristics also for higher order) ????Theory for Higher Order Resonances ????? Dana and coworkers
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.