2022/06/26 更新

写真a

ゴバン アキヒサ
碁盤 晃久
所属
理工学術院 理工学術院総合研究所
職名
次席研究員(研究院講師)

経歴

  • 2015年10月
    -
    継続中

    コロラド大学ボルダー校   JILA   ポスドク

  • 2015年07月
    -
    2015年09月

    カリフォルニア工科大学   ポスドク

 

研究分野

  • 半導体、光物性、原子物理

論文

  • On-chip photon-pair generation in a silica microtoroidal cavity

    Yosuke Hashimoto, Akihisa Goban, Yuki Hirabayashi, Yuta Kobayashi, Tomohiro Araki, Takao Aoki

    OPTICS EXPRESS   29 ( 3 ) 3533 - 3542  2021年02月

     概要を見る

    Microcavities with high Q factor and small mode volume have the potential to be efficient and compact sources of photon pairs. Here, we demonstrate on-chip photonpair generation by spontaneous tour-wave mixing in a silica microtoroidal cavity and obtain a coincidence-to-accidental ratio of 7.4 +/- 0.1 with a pump power of 46 mu W. The heralded photons also exhibit antibunching characterized by autocorrelation function values of g(c)(()(2)) (0) = 0.57 +/- 0.03<1. Comparing with a scaling model, the main noise source is found to be spontaneous Raman scattering in the cavity. This work opens a new possible means fur realizing integrated nonclassical photon sources based on silica photonic circuits toward scalable quantum technologies. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

    DOI

  • Thermodynamics of a deeply degenerate SU(N)-symmetric Fermi gas

    Lindsay Sonderhouse, Christian Sanner, Ross B. Hutson, Akihisa Goban, Thomas Bilitewski, Lingfeng Yan, William R. Milner, Ana M. Rey, Jun Ye

    NATURE PHYSICS   16 ( 12 )  2020年12月

     概要を見る

    Many-body quantum systems can exhibit a striking degree of symmetry unparallelled in their classical counterparts. In real materials SU(N) symmetry is an idealization, but this symmetry is pristinely realized in fully controllable ultracold alkaline-earth atomic gases. Here, we study an SU(N)-symmetric Fermi liquid of(87)Sr atoms, whereNcan be tuned to be as large as 10. In the deeply degenerate regime, we show through precise measurements of density fluctuations and expansion dynamics that the largeNof spin states under SU(N) symmetry leads to pronounced interaction effects in a system with a nominally negligible interaction parameter. Accounting for these effects, we demonstrate thermometry accurate to 1% of the Fermi energy. We also demonstrate record speed for preparing degenerate Fermi seas enabled by the SU(N)-symmetric interactions, reachingT/T-F = 0.22 with 10 nuclear spin states in 0.6 s working with a laser-cooled sample. This, along with the introduction of a new spin polarizing method, enables the operation of a three-dimensional optical lattice clock in the band insulating regime.Ultracold alkaline-earth fermionic atoms with large number of nuclear spin states possess SU(N) symmetry. That deeply affects their interaction properties, and allows a Fermi gas of these atoms to be cooled quickly to the quantum degenerate regime.

    DOI

  • Demonstration of 4.8 x10(-17) stability at 1s for two independent optical clocks

    E. Oelker, R. B. Hutson, C. J. Kennedy, L. Sonderhouse, T. Bothwell, A. Goban, D. Kedar, C. Sanner, J. M. Robinson, G. E. Marti, D. G. Matei, T. Legero, M. Giunta, R. Holzwarth, F. Riehle, U. Sterr, J. Ye

    NATURE PHOTONICS   13 ( 10 ) 714 - +  2019年10月

     概要を見る

    Optical atomic clocks require local oscillators with exceptional optical coherence owing to the challenge of performing spectros-copy on their ultranarrow-linewidth clock transitions. Advances in laser stabilization have thus enabled rapid progress in clock precision. A new class of ultrastable lasers based on cryogenic silicon reference cavities has recently demonstrated the longest optical coherence times to date. Here we utilize such a local oscillator with two strontium (Sr) optical lattice clocks to achieve an advance in clock stability. Through an anti-synchronous comparison, the fractional instability of both clocks is assessed to be 4.8 x 10(-17) / root tau for an averaging time tau (in seconds). Synchronous interrogation enables each clock to average at a rate of 3.5 x 10(-17) / root tau, dominated by quantum projection noise, and reach an instability of 6.6 x 10(-19) over an hour-long measurement. The ability to resolve sub-10(-18)-level frequency shifts in such short timescales will affect a wide range of applications for clocks in quantum sensing and fundamental physics.

    DOI

  • Engineering Quantum States of Matter for Atomic Clocks in Shallow Optical Lattices

    Ross B. Hutson, Akihisa Goban, G. Edward Marti, Lindsay Sonderhouse, Christian Sanner, Jun Ye

    PHYSICAL REVIEW LETTERS   123 ( 12 )  2019年09月

     概要を見る

    We investigate the effects of stimulated scattering of optical lattice photons on atomic coherence times in a state-of-the art Sr-87 optical lattice clock. Such scattering processes are found to limit the achievable coherence times to less than 12 s (corresponding to a quality factor of 1 x 10(16)), significantly shorter than the predicted 145(40) s lifetime of Sr-87's excited clock state. We suggest that shallow, state-independent optical lattices with increased lattice constants can give rise to sufficiently small lattice photon scattering and motional dephasing rates as to enable coherence times on the order of the clock transition's natural lifetime. Not only should this scheme be compatible with the relatively high atomic density associated with Fermi-degenerate gases in three-dimensional optical lattices, but we anticipate that certain properties of various quantum states of matter-such as the localization of atoms in a Mott insulator-can be used to suppress dephasing due to tunneling.

    DOI

  • Emergence of multi-body interactions in a fermionic lattice clock

    Goban A, Hutson R. B, Marti G. E, Campbell S. L, Perlin M. A, Julienne P. S, D'Incao J. P, Rey A. M, Ye J

    NATURE   563 ( 7731 ) 369 - +  2018年11月  [査読有り]

    DOI

  • Frequency Measurements of Superradiance from the Strontium Clock Transition

    Matthew A. Norcia, Julia R. K. Cline, Juan A. Muniz, John M. Robinson, Ross B. Hutson, Akihisa Goban, G. Edward Marti, Jun Ye, James K. Thompson

    PHYSICAL REVIEW X   8 ( 2 )  2018年05月  [査読有り]

     概要を見る

    We present the first characterization of the spectral properties of superradiant light emitted from the ultranarrow, 1-mHz-linewidth optical clock transition in an ensemble of cold Sr-87 atoms. Such a light source has been proposed as a next-generation active atomic frequency reference, with the potential to enable high-precision optical frequency references to be used outside laboratory environments. By comparing the frequency of our superradiant source to that of a state-of-the-art cavity-stabilized laser and optical lattice clock, we observe a fractional Allan deviation of 6.7(1) x 10(-16) at 1 s of averaging, establish absolute accuracy at the 2-Hz (4 x 10(-15) fractional frequency) level, and demonstrate insensitivity to key environmental perturbations.

    DOI

  • Imaging Optical Frequencies with 100 mu Hz Precision and 1.1 mu m Resolution

    G. Edward Marti, Ross B. Hutson, Akihisa Goban, Sara L. Campbell, Nicola Poli, Jun Ye

    PHYSICAL REVIEW LETTERS   120 ( 10 )  2018年03月  [査読有り]

     概要を見る

    We implement imaging spectroscopy of the optical clock transition of lattice-trapped degenerate fermionic Sr in the Mott-insulating regime, combining micron spatial resolution with submillihertz spectral precision. We use these tools to demonstrate atomic coherence for up to 15 s on the clock transition and reach a record frequency precision of 2.5 x 10(-19). We perform the most rapid evaluation of trapping light shifts and record a 150 mHz linewidth, the narrowest Rabi line shape observed on a coherent optical transition. The important emerging capability of combining high-resolution imaging and spectroscopy will improve the clock precision, and provide a path towards measuring many-body interactions and testing fundamental physics.

    DOI

  • A Fermi-degenerate three-dimensional optical lattice clock

    S. L. Campbell, R. B. Hutson, G. E. Marti, A. Goban, N. Darkwah Oppong, R. L. McNally, L. Sonderhouse, J. M. Robinson, W. Zhang, B. J. Bloom, J. Ye

    SCIENCE   358 ( 6359 ) 90 - 93  2017年10月  [査読有り]

     概要を見る

    Strontium optical lattice clocks have the potential to simultaneously interrogate millions of atoms with a high spectroscopic quality factor of 4 x 10(17). Previously, atomic interactions have forced a compromise between clock stability, which benefits from a large number of atoms, and accuracy, which suffers from density-dependent frequency shifts. Here we demonstrate a scalable solution that takes advantage of the high, correlated density of a degenerate Fermi gas in a three-dimensional (3D) optical lattice to guard against on-site interaction shifts. We show that contact interactions are resolved so that their contribution to clock shifts is orders of magnitude lower than in previous experiments. A synchronous clock comparison between two regions of the 3D lattice yields a measurement precision of 5 x 10(-19) in 1 hour of averaging time.

    DOI

  • Atom-atom interactions around the band edge of a photonic crystal waveguide

    Jonathan D. Hood, Akihisa Goban, Ana Asenjo-Garcia, Mingwu Lu, Su-Peng Yu, Darrick E. Chang, H. J. Kimble

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   113 ( 38 ) 10507 - 10512  2016年09月  [査読有り]

     概要を見る

    Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields E(x) proportional to e(+/- ikxx) outside the bandgap to localized fields E(x) proportional to e(-kx vertical bar x vertical bar) within the bandgap should be accompanied by a transition from largely dissipative atom-atom interactions to a regime where dispersive atom-atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the D-1 line of atomic cesium for (N) over bar = 3.0 +/- 0.5 atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom-atom interactions with low dissipation into the guided mode.

    DOI

  • Large Bragg Reflection from One-Dimensional Chains of Trapped Atoms Near a Nanoscale Waveguide

    Neil V. Corzo, Baptiste Gouraud, Aveek Chandra, Akihisa Goban, Alexandra S. Sheremet, Dmitriy V. Kupriyanov, Julien Laurat

    PHYSICAL REVIEW LETTERS   117 ( 13 )  2016年09月  [査読有り]

     概要を見る

    We report experimental observations of a large Bragg reflection from arrays of cold atoms trapped near a one-dimensional nanoscale waveguide. By using an optical lattice in the evanescent field surrounding a nanofiber with a period nearly commensurate with the resonant wavelength, we observe a reflectance of up to 75% for the guided mode. Each atom behaves as a partially reflecting mirror and an ordered chain of about 2000 atoms is sufficient to realize an efficient Bragg mirror. Measurements of the reflection spectra as a function of the lattice period and the probe polarization are reported. The latter shows the effect of the chiral character of nanoscale waveguides on this reflection. The ability to control photon transport in 1D waveguides coupled to spin systems would enable novel quantum network capabilities and the study of many-body effects emerging from long-range interactions.

    DOI

  • Superradiance for Atoms Trapped along a Photonic Crystal Waveguide

    A. Goban, C. -L. Hung, J. D. Hood, S. -P. Yu, J. A. Muniz, O. Painter, H. J. Kimble

    PHYSICAL REVIEW LETTERS   115 ( 6 )  2015年08月  [査読有り]

     概要を見る

    We report observations of superradiance for atoms trapped in the near field of a photonic crystal waveguide (PCW). By fabricating the PCW with a band edge near the D-1 transition of atomic cesium, strong interaction is achieved between trapped atoms and guided-mode photons. Following short-pulse excitation, we record the decay of guided-mode emission and find a superradiant emission rate scaling as (Gamma) over bar (SR) proportional to (N) over bar Gamma(1D) for average atom number 0.19 less than or similar to(N) over bar less than or similar to 2.6 atoms, where Gamma(1D)/Gamma' = 1.0 +/- 0.1 is the peak single-atom radiative decay rate into the PCW guided mode, and Gamma' is the radiative decay rate into all the other channels. These advances provide new tools for investigations of photon-mediated atom-atom interactions in the many-body regime.

    DOI

  • Atom-light interactions in photonic crystals

    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, H. J. Kimble

    NATURE COMMUNICATIONS   5  2014年05月  [査読有り]

     概要を見る

    The integration of nanophotonics and atomic physics has been a long-sought goal that would open new frontiers for optical physics, including novel quantum transport and many-body phenomena with photon-mediated atomic interactions. Reaching this goal requires surmounting diverse challenges in nanofabrication and atomic manipulation. Here we report the development of a novel integrated optical circuit with a photonic crystal capable of both localizing and interfacing atoms with guided photons. Optical bands of a photonic crystal waveguide are aligned with selected atomic transitions. From reflection spectra measured with average atom number (N) over bar = 1: 1 +/- 0: 4, we infer that atoms are localized within the waveguide by optical dipole forces. The fraction of single-atom radiative decay into the waveguide is Gamma(1D)/Gamma' similar or equal to (0.32 +/- 0.08), where Gamma(1D) is the rate of emission into the guided mode and Gamma' is the decay rate into all other channels. Gamma(1D)/Gamma' is unprecedented in all current atom-photon interfaces.

    DOI

  • Trapped atoms in one-dimensional photonic crystals

    Sean M. Meenehan, Chen-Lung Hung, Justin D. Cohen, Richard Norte, Akihisa Goban, Su-Peng Yu, Jonathan Hood, Darrick E. Chang, Oskar Painter, H. Jeff Kimble

    2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)    2013年  [査読有り]

     概要を見る

    We present one-dimensional photonic crystal waveguides which can stably trap neutral atoms and achieve single-atom reflectivities of r(0) greater than or similar to 0.9, as well as experimental progress towards fabrication and optical testing of such structures. (C) 2013 Optical Society of America

  • Demonstration of a State-Insensitive, Compensated Nanofiber Trap

    A. Goban, K. S. Choi, D. J. Alton, D. Ding, C. Lacroute, M. Pototschnig, T. Thiele, N. P. Stern, H. J. Kimble

    PHYSICAL REVIEW LETTERS   109 ( 3 )  2012年07月  [査読有り]

     概要を見る

    We report the experimental realization of an optical trap that localizes single Cs atoms similar or equal to 215 nm from the surface of a dielectric nanofiber. By operating at magic wavelengths for pairs of counterpropagating red-and blue-detuned trapping beams, differential scalar light shifts are eliminated, and vector shifts are suppressed by approximate to 250. We thereby measure an absorption linewidth Gamma/2 pi = 5.7 +/- 0.1 MHz for the Cs 6S(1/2), F = 4 -&gt; 6P(3/2), F' = 5 transition, where Gamma(0)/2 pi = 5.2 MHz in free space. An optical depth d similar or equal to 66 is observed, corresponding to an optical depth per atom d(1) similar or equal to 0.08. These advances provide an important capability for the implementation of functional quantum optical networks and precision atomic spectroscopy near dielectric surfaces.

    DOI

  • A state-insensitive, compensated nanofiber trap

    C. Lacroute, K. S. Choi, A. Goban, D. J. Alton, D. Ding, N. P. Stern, H. J. Kimble

    NEW JOURNAL OF PHYSICS   14  2012年02月  [査読有り]

     概要を見る

    Laser trapping and interfacing of laser-cooled atoms in an optical fiber network is an important tool for quantum information science. Following the pioneering work of Balykin et al (2004 Phys. Rev. A 70 011401) and Vetsch et al (2010 Phys. Rev. Lett. 104 203603), we propose a robust method for trapping single cesium atoms with a two-color state-insensitive evanescent wave around a dielectric nanofiber. Specifically, we show that vector light shifts (i.e. effective inhomogeneous Zeeman broadening of the ground states) induced by the inherent ellipticity of the forward-propagating evanescent wave can be effectively canceled by a backward-propagating evanescent wave. Furthermore, by operating the trapping lasers at the magic wavelengths, we remove the differential scalar light shift between ground and excited states, thereby allowing for resonant driving of the optical D-2 transition. This scheme provides a promising approach to trap and probe neutral atoms with long trap and coherence lifetimes with realistic experimental parameters.

    DOI

  • Entanglement of spin waves among four quantum memories

    K. S. Choi, A. Goban, S. B. Papp, S. J. van Enk, H. J. Kimble

    NATURE   468 ( 7322 ) 412 - U235  2010年11月  [査読有り]

     概要を見る

    Quantum networks are composed of quantum nodes that interact coherently through quantum channels, and open a broad frontier of scientific opportunities(1). For example, a quantum network can serve as a 'web' for connecting quantum processors for computation(2,3) and communication(4), or as a 'simulator' allowing investigations of quantum critical phenomena arising from interactions among the nodes mediated by the channels(5,6). The physical realization of quantum networks generically requires dynamical systems capable of generating and storing entangled states among multiple quantum memories, and efficiently transferring stored entanglement into quantum channels for distribution across the network. Although such capabilities have been demonstrated for diverse bipartite systems(7-12), entangled states have not been achieved for interconnects capable of 'mapping' multipartite entanglement stored in quantum memories to quantum channels. Here we demonstrate measurement-induced entanglement stored in four atomic memories; user-controlled, coherent transfer of the atomic entanglement to four photonic channels; and characterization of the full quadripartite entanglement using quantum uncertainty relations(13-16). Our work therefore constitutes an advance in the distribution of multipartite entanglement across quantum networks. We also show that our entanglement verification method is suitable for studying the entanglement order of condensed-matter systems in thermal equilibrium(17,18).

    DOI

  • Laser-field-free molecular orientation

    Akihisa Goban, Shinichirou Minemoto, Hirofumi Sakai

    PHYSICAL REVIEW LETTERS   101 ( 1 )  2008年07月  [査読有り]

     概要を見る

    We demonstrate laser-field-free molecular orientation with the combination of a moderate electrostatic field and an intense nonresonant rapidly turned-off laser field, which can be shaped with the plasma shutter technique. We use OCS (carbonyl sulfide) molecules as a sample. Molecular orientation is adiabatically created in the rising part of the laser pulse, and it is found to revive at around the rotational period of an OCS molecule with the same degree of orientation as that at the peak of the laser pulse in the virtually laser-field-free condition. This accomplishment means that a new class of molecular sample has become available for various applications.

    DOI

  • Laser-field-free molecular orientation with combined electrostatic and rapidly-turned-off laser fields

    Yu Sugawara, Akihisa Goban, Shinichirou Minemoto, Hirofumi Sakai

    PHYSICAL REVIEW A   77 ( 3 )  2008年03月  [査読有り]

     概要を見る

    We propose a strategy to achieve laser-field-free molecular orientation with the combination of an electrostatic field and an intense, nonresonant laser field with rapid turn off. The adiabatically created pendular state is effectively transferred to the rotational wave packet in the nonadiabatic regime after the rapid turn off of the laser pulse and the orientation achieved at the peak of the laser pulse is revived at the rotational period of the molecule with the same degree of orientation. The remarkable difference in molecular behavior is found between alignment and orientation, which reveals the crucial importance of the sufficiently long rising time of the laser pulse to achieve the highest possible degree of orientation. The feasibility has been examined for OCS molecules as a sample under practical experimental conditions.

    DOI

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