Purdue Physics: Hung Lab: Ultracold quantum gas and quantum optics: quantum optics result

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Recent results on quantum optics

Achieving strong radiative interactions between single atoms and the fields of nanoscopic optical waveguides or resonators has been a long quest in quantum information science [1]. Strong atom-photon interactions also present new opportunities in atomic based quantum simulators as photon mediated interactions lead to novel quantum spin dynamics and transport phenomena. For this purpose, we have designed a one-dimensional (1D) photonic crystals that support a waveguide mode suitable for far-off resonant optical trap (FORT) for neutral atoms within a unit cell, as well as a second probe mode that accommodates strong atom-photon interactions. Moreover, we have investigated and analyzed a new hybrid trap that combines optical and Casimir-Polder forces to achieve realistic and stable trapping near dielectric nanostructures. By band structure engineering, the atom-photon coupling rate into the probe mode can exceed the rate into all other modes by more than tenfold [2], enabling diverse investigations of photon-mediated interactions for 1D and 2D atomic lattices and waveguide QED [3, 4]. We have implemented this theoretical framework in the following experiments:

Atom-light interaction in 1D photonic crystals

We designed and fabricated 1D Silicon-Nitrite dielectric waveguides [5], and studied atom-light interactions using laser-cooled cesium atoms [6]. By using a guided mode as a FORT, we observed that single atoms can be efficiently guided into the nano-waveguide. We measured a large coupling rate to the waveguide mode, about 0.4 times (now up to 3 times) the freespace decay rate, and achieved ~30% (now 75%) single-atom reflectivity of the probe mode. Our result exceeds state-of-the-art nanofiber experiments by ten-fold, entering a regime that collective light transport along a 1D chain of atoms can be excited.

Figure 4 (a) Scanning electron micrograph of the "alligator" 1D waveguide and (b, c) the guided mode intensity profiles. The waveguide supports guided modes with large field amplitude in the gap. (b) Atoms (green circles) are confined in the low-intensity region of a blue-detuned FORT mode, and can couple to the probe mode (c) efficiently.

For more details, see A. Goban, C.-L. Hung, S.-P. Yu, J. D. Hood, J. A. Muniz et al. Nature Comm. 5, 3808 (2014) [6].

See also: Kimble group and Painter group at Caltech.

References

[1] H. J. Kimble, The quantum internet. Nature 453, 1023 (2008).

[2] C.-L. Hung, S. M. Meenehan, D. E. Chang, O. Painter and H. J. Kimble, Trapped Atoms in One-Dimensional Photonic Crystals. New J. Phys. 15, 083026 (2013).

[3] J. S. Douglas, H. Habibian, C.-L. Hung , A. V. Gorshkov, H. J. Kimble and D. E. Chang, Photonic crystal cavities created by single atoms enable tunable long-range interactions. accepted by Nature Photonics (2015).

[4] A. González-Tudela, C.-L. Hung , D. E. Chang, H. J. Kimble and I. Cirac, Subwavelength vacuum lattices and photon-mediated atomic interactions in photonic crystals. arXiv:1407.7336 (2014).

[5] S.-P. Yu, J. D. Hood, J. A. Muniz, M. J. Martin, R. Norte, C.-L. Hung , S. M. Meenehan, J. D. Cohen, O. Painter and H. J. Kimble, Nanowire photonic crystal waveguides for single-atom trapping and strong light-matter interactions. Appl. Phys. Lett. 104, 111103 (2014).

[6] A. Goban, C.-L. Hung, S.-P. Yu, J. D. Hood, J. A. Muniz, J. H. Lee, M. J. Martin, A. C. McClung, K. S. Choi, D. E. Chang, O. Painter and H. J. Kimble, Atom-Light Interactions in Photonic Crystals. Nature Comm. 5, 3808 (2014).