1. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 1yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Lecture 23 Laser cooling; cold atoms & ions Reminder: Lecture notes taker: none(?) HWK 5 problem 12.3 deleted (assigned before); due date Wed 4/30 class Paper due Wed 4/30 Final exam date: 5/5 Monday evening 7-9pm Room 201 self-made 1 eq. sheet permitted; FQ (all) + FO (1-5) Please fill out course evaluation

2. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 2yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Bagwell Lecture 2014 New frontiers in Optics and Photonics with Designer Electronic and Optical Materials Federico Capasso, Professor and Research Fellow, Harvard University The control of electrons and photons in artificially structured materials at the nanoscale by quantum and electromagnetic design has opened unique opportunities for major advances in science and technology. I will present a tutorial account of some these developments. From the design of the electronic resonances and their coupling to light in nanometer thick materials a new class of light sources (quantum cascade lasers) has emerged that now cover almost the entire infrared and far-infrared spectrum, leading to an explosive growth in applications. By structuring surfaces at the sub-wavelength with nanoscale optical resonators and nanometer thin layers “metasurfaces" have emerged that have led to powerful generalizations of the laws or reflection and refraction, new thin film interferences and new ways to generate light beams and surface optical waves with “arbitrary” wavefronts. Applications of this new “flat optics” will be presented. Finally, I will show how quantum fluctuations at the nanoscale can be designed to control macroscopic quantum electrodynamical phenomena such as attractive and repulsive Casimir forces and their interaction with micro/nanomechanical structures. May 14 2 – 3pm burton morgan room 121

3. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 3yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Course Outline Part 1: basic review: Optics+Quantum; Part 2: Basic Light- matter interaction; laser; Part 3: Quantum Optics of photons Part 4: More advanced light-matter interaction Part 5: Quantum information/photonics/ applications Subject to change; Check updates on course web/wiki

4. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 4yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Plan today (FQ Chap 11) Student Presentation: Brian Fields: Introduction to trapped ions and applications in quantum computing Further studies: Metcalf & van der Straten: laser cooling & trapping

5. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 5yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Laser Cooling D.J. Wineland, H. Dehmelt: Bull. Am. Phys. SOC. 20, 637 (1975) Neutral atoms ions 2005 1981 2012 1989 1997 2001 Atomic BEC Laser cooling/trapping The most “nobel” idea!

6. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 6yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Laser cooling: basic idea Light force (momentum transfer) Doppler effect Absorption-emission (even works for solid)

7. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 7yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ (doppler limit) Doppler cooling force

8. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 8yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Optical Molasses (Doppler temperature) (~.1mK)

9. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 9yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Actually works better: subdoppler cooling Absorption-emission Recoil limit (~ uK)

10. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 10yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Experimental implementation Zeeman slower

11. Creating BECs @ Purdue Magneto Optical Trap Optical Trap and Evaporation Bose- Einstein Condensate Experi- ments w/ BECs 80  K  20  K80  K  <20 nK QM ground state  =1x10 -5  =1x10 -4 to 2.6  >2.6 ++ -- -- -- ++ ++ I curr (slides by A. Olson)

12. Experimental Setup 15mm 4.5mm Elliptical High Pressure MOT Science Chamber MOT Credit: Ping Wang design and initial construction 7 lasers >220 optical components >45 Electronic devices Computer control Vacuum system Imaging system Rb87

13. 8x8um pixels. Magnification gives 4.3 um/px Absorption Imaging Lens system: NA is 0.19 and resolution is 2.5 um. Resonant Laser 30 mm diameter 80 mm fl Gradium lens 50 mm diameter 150 mm fl Achromatic doublet ++ -- -- -- ++ ++ I curr

14. TOF Absorption Imaging Time of flight imaging MOT Lasers / Mag fields TOF (0 to 20 ms) Imaging pulse tt 3.4 mm

15. Evaporative cooling in optical traps Far off-resonance dipole traps: 30 W of 1550 nm light Waferboard / Flickr

16. Loading the Dipole Trap 3.4 mm

17. Cold Atom Collisions Two-body collisions: Thermalization and evaporation Forced evaporation

18. Theory Results Lowering final trap depth (15 ms TOF) 80 um

19. With mean field approximation, described by Gross-Pitaevskii equation KineticPotentialContact (Mean field) Quantum Description Lowering final trap depth (15 ms TOF) 80 um

20. -1 0 +1 Spins (m f ) RF driven spin Rai oscillation m F =-1 0 +1 Experimental AMO (esp. cold atoms) research --- “seeing” quantum mechanics & dynamics! (“slowed down” and “blown up” so much that you can shoot photos & videos!) (Stern-Gerlach: separate BECs with different spins) B-field gradient “coldest place in Indiana” (<50nK) -- laser cooled & trapped atoms in PHYS G61 coherent oscillation of BEC between 3 spin states BEC (matter wave) diffraction from laser standing wave (optical grating) Demo with our Bose-Einstein Condensation (BEC) Purdue QMD’s “all-optical” Rb87 BEC apparatus With synthetic gauge fields and spin-orbit coupling

21. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 21yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Atom (quantum) Optics & Atom Laser

22. Purdue University Spring 2014 Prof. Yong P. Chen (yongchen@purdue.edu) Lecture 16 (3/31/2014) Slide 22yongchen@purdue.edu Introduction to Quantum Optics & Quantum Photonics PHYS522 ECE695 (“Coherent Optics & Quantum Electronics”) http://www.physics.purdue.edu/academic_programs/courses/phys522/ Signatures of BEC Bimodal distribution Anisotropic expansion Matter interference superfluidity Cornell/Weiman ketterle