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Coherent excitation of Rydberg atoms on an atom chip

Coherent excitation of Rydberg atoms on an atom chip. Rutger M. T. Thijssen Van der Waals - Zeeman Instituut voor Experimentele Natuurkunde. Quantum Information Processing. Qubits Coherence Switchable interactions Scalability. MAGCHIPS. “Atom chip” (room temperature). 22 µ m.

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Coherent excitation of Rydberg atoms on an atom chip

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  1. Coherent excitation of Rydberg atoms on an atom chip Rutger M. T. Thijssen Van der Waals - Zeeman Instituut voor Experimentele Natuurkunde

  2. Quantum Information Processing • Qubits • Coherence • Switchable interactions • Scalability

  3. MAGCHIPS

  4. “Atom chip” (room temperature) 22 µm 10 µm Magnetised film MAGCHIPS • Permanent magnetic lattice atom chip • Gold-coated for laser cooling • 500 populated magnetic microtraps Prospective qubits 87Rb, T~mK

  5. Quantum information on MAGCHIPS Neutral atoms: intrinsically weak interaction with environment Exquisite control & manipulation Scalability Stable qubits

  6. Quantum information on MAGCHIPS Intrinsically weak interaction with environment • Good: long coherence times (~sec.) • Challenge: quantum information requires interaction: we have to work to add an interaction between qubits (i.e. traps) Neutral atoms: intrinsically weak interaction with environment Exquisite control & manipulation Scalability Stable qubits

  7. Rydberg atoms • Hydrogen-like atom • High principal (n) quantum number • Large dipole-dipole interaction between Rydberg atoms • Dipole blockade

  8. |5p 780nm (infrared) |5s Rydberg Excitation |ns |nd 480nm (blue) Toptica TA-SHG 110 frequency doubled diode laser, tunable from 488-479nm (n=18-ionization threshold) (300mW) Toptica DL-100 diode laser (30mW)

  9. Electromagnetically Induced Transparency |nd |5p δωp Ωp γ12 |5s Detuning (δωp)

  10. Electromagnetically Induced Transparency |nd Ωc |5p δωp Ωp γ12 |5s Detuning (δωp)

  11. |nd Ωc |5p |a- Ωp 780nm (infrared) |5s |a0 (5s) Electromagnetically Induced Transparency – dressed states Rediagonalise interaction Hamiltonian Interference between |a+ and |a- dressed states: reduced probe absorption on two-photon resonance |a+ Autler – Townes splitting + Fano interference

  12. vapour cell EIT, |39d Coupling laser detuning (MHz) EIT – frequency stabilisation in a vapour cell 480 nm diode laser fast photodiode dichroic mirror Rubidium vapour cell dichroic mirror 780 nm diode laser

  13. EIT Imaging optical fiber

  14. EIT Imaging optical fiber

  15. EIT Imaging • Blue laser frequency locked to vapour cell EIT • Red laser scanned over resonance Optical density Detuning (MHz) Position (px)

  16. Surface effects • Near-field blackbody radiation from chip • “mirror” effect: Rydberg atom interacting with itself • Photoelectric effect on surface: adsorbed Rb, Au • Patch potentials • Crystal defects in FePt • Adsorbed Rb ions

  17. Summary • MAGCHIPS experiment • Rydberg / EIT for interactions between qubits • Built laser system • Built frequency locking setup for probe and coupling laser • Imaged Rydberg / EIT in surface magneto-optical trap • Investigating effects of surface on Rydberg levels • Build a quantum computer…

  18. Summary • MAGCHIPS experiment • Rydberg / EIT for interactions between qubits • Built laser system • Built frequency locking setup for probe and coupling laser • Imaged Rydberg / EIT in surface magneto-optical trap • Investigating effects of surface on Rydberg levels • Build a quantum computer…

  19. THANK YOU Questions? Rutger M. T. Thijssen rmeijert@science.uva.nl

  20. 2-photon gates • Zoller Mesoscopic Rydberg gates using EIT Focused lasers |0> |1> Microwave/Raman 6.8 GHz |0> |1> Rydberg interaction Ensemble A Ensemble B

  21. Rydberg Atoms • One highly excited electron (n=20-100) • Rydberg formula: • Size ~ n^2 • Lifetime ~ n^3 • Polarisability ~n^7 • Van der Waals interaction ~ n^11 • Dipole blockade shifts nearby Rydberg levels

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