Kevin J. Weatherill. Joint Quantum Centre (Durham-Newcastle) Department of Physics Durham University

Transcription

1 Non-equilibrium phase transition in a dilute thermal gas. Joint Quantum Centre (Durham-Newcastle) Department of Physics Durham University

2 Non-equilibrium phase transition in a dilute thermal gas. Talk Outline 1. Non-linear optics using Rydberg atoms 2. Optical bistability and phase transitions 3. Experiment and results 4. Outlook: Non-local effects and THz detection? 5. Acknowledgements

3 Rydberg Atoms s p d Rydberg states: large n (>20) Scaling with principal quantum number n Size n 2 Dipole moment n 2 Lifetime n 3 long lived Polarizability n 7 Sensitive to electric fields Van der Waals n 11 Strong atom-atom interactions Dipole moment n -3/2 Weak atom-light interactions of optical transitions

4 Rydberg Atoms s p d Rydberg states: large n (>20) Scaling with principal quantum number n Size n 2 Dipole moment n 2 Lifetime n 3 long lived Polarizability n 7 Sensitive to electric fields Van der Waals n 11 Strong atom-atom interactions Dipole moment n -3/2 Weak atom-light interactions of optical transitions Range of interaction >> interatomic spacing > excitation wavelength

5 Rydberg Atoms s p d Rydberg states: large n (>20) Scaling with principal quantum number n Size n 2 Dipole moment n 2 Lifetime n 3 long lived Polarizability n 7 Sensitive to electric fields Van der Waals n 11 Strong atom-atom interactions Dipole moment n -3/2 Weak atom-light interactions of optical transitions Range of interaction >> interatomic spacing > excitation wavelength Strongly interacting systems

6 Rydberg Non-linear (and Quantum) Optics. Back-action on the light field Coherent optical detection of Rydberg atoms (Adams: Durham)

7 Rydberg Non-linear (and Quantum) Optics. Back-action on the light field Coherent optical detection of Rydberg atoms (Adams: Durham) 2008 Giant DC Kerr non-linearities E field sensitivity

8 Rydberg Non-linear (and Quantum) Optics. Back-action on the light field Coherent optical detection of Rydberg atoms (Adams: Durham) 2008 Giant DC Kerr non-linearities E field sensitivity 2010 Cooperative optical non-linearities Atom-atom interactions

9 Rydberg Non-linear (and Quantum) Optics. Back-action on the light field Coherent optical detection of Rydberg atoms (Adams: Durham) 2008 Giant DC Kerr non-linearities E field sensitivity 2010 Cooperative optical non-linearities Atom-atom interactions 2012 Single photon sources (Kuzmich: Georgia-Tech, Lukin + Vuletic, Harvard) 2013 Microwave controlled interactions between optical photons (Adams, Durham) 2013 Single photon switch (Durr + Rempe, Garching) + many others Pfau, Weidemuller, Grangier, Spreeuw etc. Non-linear optics using cold Rydberg Atoms J. D. Pritchard, K. J. Weatherill and C. S. Adams Annual Review of Cold Atoms and Molecules 1, 301 (2013) Arxiv:

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20 Intrinsic Optical Bistability First- and second-order phase transitions in the Dicke model: Relation to optical bistability Bowden and Sung, Phys. Rev. A 19, 2393 (1979) feedback Experimental observation using Yb ions in crystal Atoms 31 K Simple Optical Bloch model 27 K 23 K 19 K 15 K 11 K Can we observe intrinsic optical bistability in a dilute Rydberg gas at room temperature? Hehlen et al, Phys. Rev. Lett. 73, 1103 (1994)

21 Experiment: Three Step Excitation Scheme. Caesium Cheap, convenient and simple to use IR diode lasers High power and wide tunability on final step 21

22 3-photon spectroscopy. Scanned Locked Locked Probe Cooperative non-equilibrium phase transition in a dilute Rydberg ensemble C. Carr, C. Wade, R. Ritter, C. S. Adams and K. J. Weatherill, Phys Rev. Lett 111, (2013) 22

23 3-photon spectroscopy. Scanned Locked Locked Probe Cooperative non-equilibrium phase transition in a dilute Rydberg ensemble C. Carr, C. Wade, R. Ritter, C. S. Adams and K. J. Weatherill, Phys Rev. Lett 111, (2013) 23

24 Fluorescence Spectra. transmission fluorescence Spectrometer and PMT Lasers Cooperative non-equilibrium phase transition in a dilute Rydberg ensemble C. Carr, C. Wade, R. Ritter, C. S. Adams and K. J. Weatherill, Phys Rev. Lett 111, (2013) 24

25 Fluorescence Spectra. transmission fluorescence Spectrometer and PMT Lasers Cooperative non-equilibrium phase transition in a dilute Rydberg ensemble C. Carr, C. Wade, R. Ritter, C. S. Adams and K. J. Weatherill, Phys Rev. Lett 111, (2013) 25

26 Fluorescence Spectra. transmission fluorescence Spectrometer and PMT Lasers Cooperative non-equilibrium phase transition in a dilute Rydberg ensemble C. Carr, C. Wade, R. Ritter, C. S. Adams and K. J. Weatherill, Phys Rev. Lett 111, (2013) 26

27 Fluorescence Spectra. transmission fluorescence Spectrometer and PMT Lasers Cooperative non-equilibrium phase transition in a dilute Rydberg ensemble C. Carr, C. Wade, R. Ritter, C. S. Adams and K. J. Weatherill, Phys Rev. Lett 111, (2013) 27

28 Fluorescence Spectra. transmission fluorescence Spectrometer and PMT Lasers Cooperative non-equilibrium phase transition in a dilute Rydberg ensemble C. Carr, C. Wade, R. Ritter, C. S. Adams and K. J. Weatherill, Phys Rev. Lett 111, (2013) 28

29 Longitudinal Phase Transition Lasers Cooperative non-equilibrium phase transition in a dilute Rydberg ensemble C. Carr, C. Wade, R. Ritter, C. S. Adams and K. J. Weatherill, Phys Rev. Lett 111, (2013)

30 Critical Slowing Down Critical slowing down is key signature of OB and phase transition. G. Grynberg et al, J. Phys. Lett. 44, 449 (1983)

31 Non-equilibrium phase transition in a dilute thermal gas. Extreme regime with strong driving and strong dissipation Laser driving superradiant dissipation Simple Optical Bloch model dynamic equilibrium Mean-field effect from long-range and thermally averaged atom-atom interactions Quantum soft matter?

32 Outlook. Interesting new regime with Interesting possibilities. THz Can we detect THz radiation? lasers Non-local switching experiments? Investigate geometric effects on Superradiance? And lots more.. Quantum statistics of photons etc.

33 Recap. Talk Outline 1. Non-linear optics using Rydberg atoms 2. Optical Bistability and phase transitions 3. Experiment and results 4. Outlook: Non-local effects and THz detection?

34 Acknowledgements Chris Carr, Ralf Ritter, Chris Wade, Charles Adams. Seedcorn award. EU Marie Curie ITN COHERENCE Network.