Near-Ground-State Cooling of Atoms Optically Trapped 300 nm Away from a Hot Surface

Laser-cooled atoms coupled to nanophotonic structures constitute a powerful research platform for the exploration of new regimes of light-matter interaction. While the initialization of the atomic internal degrees of freedom in these systems has been achieved, a full preparation of the atomic quantum state also requires controlling the center of mass motion of the atoms at the quantum level. Obtaining such control is not straightforward, due to the close vicinity of the atoms to the photonic system that is at ambient temperature. Here, we demonstrate cooling of individual neutral Cesium atoms, that are optically interfaced with light in an optical nanofiber, preparing them close to their three-dimensional motional ground state. The atoms are localized less than 300nm away from the hot fiber surface. Ground-state preparation is achieved by performing degenerate Raman cooling, and the atomic temperature is inferred from the analysis of heterodyne fluorescence spectroscopy signals. Our cooling method can be implemented either with externally applied or guided light fields. Moreover, it relies on polarization gradients which naturally occur for strongly confined guided optical fields. Thus, this method can be implemented in any trap based on nanophotonic structures. Our results provide an ideal starting point for the study of novel effects such as light-induced self-organization, the measurement of novel optical forces, and the investigation of heat transfer at the nanoscale using quantum probes.

[1]  A. Rauschenbeutel,et al.  Storage of fiber-guided light in a nanofiber-trapped ensemble of cold atoms , 2015, 1502.01151.

[2]  E. Polzik,et al.  Dipole force free optical control and cooling of nanofiber trapped atoms. , 2017, Optics letters.

[3]  H. J. Kimble,et al.  The quantum internet , 2008, Nature.

[4]  H. Kimble,et al.  Trapping atoms using nanoscale quantum vacuum forces , 2013, Nature Communications.

[5]  S. Chu,et al.  Degenerate Raman Sideband Cooling of Trapped Cesium Atoms at Very High Atomic Densities , 1998 .

[6]  Chu,et al.  Beyond optical molasses: 3D raman sideband cooling of atomic cesium to high phase-space density , 2000, Physical review letters.

[7]  A. Rauschenbeutel,et al.  Coherence properties of nanofiber-trapped cesium atoms. , 2013, Physical review letters.

[8]  Zach DeVito,et al.  Opt , 2017 .

[9]  S. Scheel,et al.  Directional spontaneous emission and lateral Casimir-Polder force on an atom close to a nanofiber , 2015, 1505.01275.

[10]  Andrew G. Glen,et al.  APPL , 2001 .

[11]  Dispersive response of atoms trapped near the surface of an optical nanofiber with applications to quantum nondemolition measurement and spin squeezing , 2015, 1509.02625.

[12]  C. Salomon,et al.  NEUTRAL ATOMS PREPARED IN FOCK STATES OF A ONE-DIMENSIONAL HARMONIC POTENTIAL , 1999 .

[13]  S. Dawkins,et al.  Optical interface created by laser-cooled atoms trapped in the evanescent field surrounding an optical nanofiber. , 2009, Physical review letters.

[14]  Franco Nori,et al.  Extraordinary momentum and spin in evanescent waves , 2013, Nature Communications.

[15]  J. Dalibard,et al.  Quantum simulations with ultracold quantum gases , 2012, Nature Physics.

[16]  Optically active mechanical modes of tapered optical fibers , 2013, 1311.0916.

[17]  J. Cirac,et al.  Self-organization of atoms along a nanophotonic waveguide. , 2012, Physical review letters.

[18]  C. Regal,et al.  Cooling a Single Atom in an Optical Tweezer to Its Quantum Ground State , 2012, 1209.2087.

[19]  D. Chang,et al.  Self-organization of atoms coupled to a chiral reservoir. , 2016, Physical review. A.

[20]  F. J. Rodríguez-Fortuño,et al.  Lateral forces on circularly polarizable particles near a surface , 2015, Nature Communications.

[21]  J Laurat,et al.  Demonstration of a memory for tightly guided light in an optical nanofiber. , 2015, Physical review letters.

[22]  Manoj Das,et al.  Measurement of fluorescence emission spectrum of few strongly driven atoms using an optical nanofiber. , 2010, Optics express.

[23]  M. Wilde,et al.  Optical Atomic Clocks , 2019, 2019 URSI Asia-Pacific Radio Science Conference (AP-RASC).

[24]  S. Scheel,et al.  Friction forces on atoms after acceleration , 2015, Journal of physics. Condensed matter : an Institute of Physics journal.

[25]  V. Vuletić,et al.  Creation of a Bose-condensed gas of 87Rb by laser cooling , 2017, Science.

[26]  S. Stenholm,et al.  Laser cooling of trapped particles III: The Lamb-Dicke limit , 1981 .

[27]  Martin Wilkens,et al.  Heating of trapped atoms near thermal surfaces , 1999 .

[28]  David E. Pritchard,et al.  Optics and interferometry with atoms and molecules , 2009 .

[29]  H. Ritsch,et al.  Light-induced crystallization of cold atoms in a 1D optical trap. , 2013, Physical review letters.

[30]  J. H. Müller,et al.  Coherent Backscattering of Light Off One-Dimensional Atomic Strings. , 2016, Physical review letters.

[31]  E. Cornell,et al.  Alkali-metal adsorbate polarization on conducting and insulating surfaces probed with Bose-Einstein condensates , 2004, cond-mat/0403254.

[32]  C. cohen-tannoudji,et al.  Experimental Study of Zeeman Light Shifts in Weak Magnetic Fields , 1972 .

[33]  Resolved-Sideband Raman Cooling to the Ground State of an Optical Lattice , 1998, quant-ph/9801025.

[34]  Peter Zoller,et al.  Chiral quantum optics , 2016, Nature.

[35]  M. Wilkens,et al.  Loss and heating of particles in small and noisy traps , 1999, quant-ph/9906128.

[36]  V. I. Balykin,et al.  Field intensity distributions and polarization orientations in a vacuum-clad subwavelength-diameter optical fiber , 2004 .

[37]  Dynamic consequences of optical spin–orbit interaction , 2015, 1504.01766.

[38]  S. L. Rolston,et al.  Atomic interface between microwave and optical photons , 2011, 1110.3537.

[39]  J. Laurat,et al.  Large Bragg Reflection from One-Dimensional Chains of Trapped Atoms Near a Nanoscale Waveguide. , 2016, Physical review letters.

[40]  V. Vuletić,et al.  Creation of a Bose-condensed gas of rubidium 87 by laser cooling , 2017 .

[41]  T. Thundat,et al.  Universal spin-momentum locked optical forces , 2015, 1511.02305.

[42]  R. Sarpong,et al.  Bio-inspired synthesis of xishacorenes A, B, and C, and a new congener from fuscol† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c9sc02572c , 2019, Chemical science.

[43]  Dieter Meschede,et al.  Microwave control of atomic motion in optical lattices. , 2009, Physical review letters.

[44]  A. Rauschenbeutel,et al.  Fictitious magnetic-field gradients in optical microtraps as an experimental tool for interrogating and manipulating cold atoms , 2016, 1608.02517.

[45]  Phillips,et al.  Observation of quantized motion of Rb atoms in an optical field. , 1992, Physical review letters.

[46]  J. Feist,et al.  Coupling a Single Trapped Atom to a Nanoscale Optical Cavity , 2013, Science.