Showing 1–15 of 15 results for author: Taie, S

Gain engineering and atom lasing in a topological edge state in synthetic dimensions

Authors: Takuto Tsuno, Shintaro Taie, Yosuke Takasu, Kazuya Yamashita, Tomoki Ozawa, Yoshiro Takahashi

Abstract: Recent advances in quantum technology have highlighted the importance of controlling quantum states, especially in open quantum systems, where the system interacts with the environment. Non-Hermitian quantum mechanics describes these systems. Photonic systems are a key platform for studying non-Hermitian quantum mechanics owing to their ability to engineer gain and loss. Ultracold atomic gases als… ▽ More Recent advances in quantum technology have highlighted the importance of controlling quantum states, especially in open quantum systems, where the system interacts with the environment. Non-Hermitian quantum mechanics describes these systems. Photonic systems are a key platform for studying non-Hermitian quantum mechanics owing to their ability to engineer gain and loss. Ultracold atomic gases also have been used to study non-Hermitian quantum mechanics; however, unlike photonics, gain control is challenging, limiting exploration to control of loss. In this paper, we report engineering of effective gain through evaporative cooling of judiciously selected initial thermal atoms, leading to Bose-Einstein condensation (BEC) in the excited eigenstates of a synthetic lattice. We achieve BEC formation in a topological edge state of the Su-Schrieffer-Heeger lattice in the synthetic hyperfine lattice, akin to atomic laser oscillations at a topological edge mode, that is, a topological atom laser. △ Less

Submitted 28 April, 2026; v1 submitted 21 April, 2024; originally announced April 2024.

Comments: 25 pages, 9 figures

Journal ref: Nat. Commun.17, 421 (2026)

Observation of the Sign Reversal of the Magnetic Correlation in a Driven-Dissipative Fermi Gas in Double Wells

Authors: Kantaro Honda, Shintaro Taie, Yosuke Takasu, Naoki Nishizawa, Masaya Nakagawa, Yoshiro Takahashi

Abstract: We report the observation of the sign reversal of the magnetic correlation from antiferromagnetic to ferromagnetic in a dissipative Fermi gas in double wells, utilizing the dissipation caused by on-site two-body losses in a controlled manner. We systematically measure dynamics of the nearest-neighbor spin correlation in an isolated double-well optical lattice, as well as a crossover from an isolat… ▽ More We report the observation of the sign reversal of the magnetic correlation from antiferromagnetic to ferromagnetic in a dissipative Fermi gas in double wells, utilizing the dissipation caused by on-site two-body losses in a controlled manner. We systematically measure dynamics of the nearest-neighbor spin correlation in an isolated double-well optical lattice, as well as a crossover from an isolated double-well lattice to a one-dimensional uniform lattice. In a wide range of lattice configurations over an isolated double-well lattice, we observe a ferromagnetic spin correlation, which is consistent with a Dicke type of correlation expected in the long-time limit. This work demonstrates the control of quantum magnetism in open quantum systems with dissipation. △ Less

Submitted 12 February, 2023; v1 submitted 26 May, 2022; originally announced May 2022.

Comments: 12 pages, 9 figures

Journal ref: Phys. Rev. Lett. 130, 063001 (2023)

Universal thermodynamics of an SU($N$) Fermi-Hubbard Model

Authors: Eduardo Ibarra-García-Padilla, Sohail Dasgupta, Hao-Tian Wei, Shintaro Taie, Yoshiro Takahashi, Richard T. Scalettar, Kaden R. A. Hazzard

Abstract: The SU(2) symmetric Fermi-Hubbard model (FHM) plays an essential role in strongly correlated fermionic many-body systems. In the one particle per site and strongly interacting limit ${U/t \gg 1}$, it is effectively described by the Heisenberg Hamiltonian. In this limit, enlarging the spin and extending the typical SU(2) symmetry to SU($N$) has been predicted to give exotic phases of matter in the… ▽ More The SU(2) symmetric Fermi-Hubbard model (FHM) plays an essential role in strongly correlated fermionic many-body systems. In the one particle per site and strongly interacting limit ${U/t \gg 1}$, it is effectively described by the Heisenberg Hamiltonian. In this limit, enlarging the spin and extending the typical SU(2) symmetry to SU($N$) has been predicted to give exotic phases of matter in the ground state, with a complicated dependence on $N$. This raises the question of what -- if any -- are the finite-temperature signatures of these phases, especially in the currently experimentally relevant regime near or above the superexchange energy. We explore this question for thermodynamic observables by numerically calculating the thermodynamics of the SU($N$) FHM in the two-dimensional square lattice near densities of one particle per site, using determinant Quantum Monte Carlo and Numerical Linked Cluster Expansion. Interestingly, we find that for temperatures above the superexchange energy, where the correlation length is short, the energy, number of on-site pairs, and kinetic energy are universal functions of $N$. Although the physics in the regime studied is well beyond what can be captured by low-order high-temperature series, we show that an analytic description of the scaling is possible in terms of only one- and two-site calculations. △ Less

Submitted 5 October, 2021; v1 submitted 9 August, 2021; originally announced August 2021.

Comments: 22 pages, 15 figures

Journal ref: Phys. Rev. A 104, 043316 (2021)

Observation of antiferromagnetic correlations in an ultracold SU($N$) Hubbard model

Authors: Shintaro Taie, Eduardo Ibarra-García-Padilla, Naoki Nishizawa, Yosuke Takasu, Yoshihito Kuno, Hao-Tian Wei, Richard T. Scalettar, Kaden R. A. Hazzard, Yoshiro Takahashi

Abstract: Mott insulators are paradigms of strongly correlated physics, giving rise to phases of matter with novel and hard-to-explain properties. Extending the typical SU(2) symmetry of Mott insulators to SU($N$) is predicted to give exotic quantum magnetism at low temperatures, but understanding the effect of strong quantum fluctuations for large $N$ remains an open challenge. In this work, we experimenta… ▽ More Mott insulators are paradigms of strongly correlated physics, giving rise to phases of matter with novel and hard-to-explain properties. Extending the typical SU(2) symmetry of Mott insulators to SU($N$) is predicted to give exotic quantum magnetism at low temperatures, but understanding the effect of strong quantum fluctuations for large $N$ remains an open challenge. In this work, we experimentally observe nearest-neighbor spin correlations in the SU(6) Hubbard model realized by ytterbium atoms in optical lattices. We study one-dimensional, two-dimensional square, and three-dimensional cubic lattice geometries. The measured SU(6) spin correlations are dramatically enhanced compared to the SU(2) correlations, due to strong Pomeranchuk cooling. We also present numerical calculations based on exact diagonalization and determinantal quantum Monte Carlo. The experimental data for a one-dimensional lattice agree with theory, without any fitting parameters. The detailed comparison between theory and experiment allows us to infer from the measured correlations a lowest temperature of $\left[{0.096 \pm 0.054 \, \rm{(theory)} \pm 0.030 \, \rm{(experiment)}}\right]/k_{\rm B}$ times the tunneling amplitude. For two- and three-dimensional lattices, experiments reach entropies below where our calculations converge, highlighting the experiments as quantum simulations. These results open the door for the study of long-sought SU($N$) quantum magnetism. △ Less

Submitted 15 October, 2020; originally announced October 2020.

Comments: 13 pages, 8 figures

Antiferromagnetic spin correlation of SU($\mathcal{N}$) Fermi gas in an optical super-lattice

Authors: Hideki Ozawa, Shintaro Taie, Yosuke Takasu, Yoshiro Takahashi

Abstract: Large-spin cold atomic systems can exhibit unique phenomena that do not appear in spin-1/2 systems. We report the observation of nearest-neighbor antiferromagnetic spin correlations of a Fermi gas with SU($\mathcal{N}$) symmetry trapped in an optical lattice. The precise control of the spin degrees of freedom provided by an optical pumping technique enables us a straightforward comparison between… ▽ More Large-spin cold atomic systems can exhibit unique phenomena that do not appear in spin-1/2 systems. We report the observation of nearest-neighbor antiferromagnetic spin correlations of a Fermi gas with SU($\mathcal{N}$) symmetry trapped in an optical lattice. The precise control of the spin degrees of freedom provided by an optical pumping technique enables us a straightforward comparison between the cases of SU(2) and SU(4). Our important finding is that the antiferromagnetic correlation is enhanced for the SU(4)-spin system compared with SU(2) as a consequence of a Pomeranchuk cooling effect. This work is an important step towards the realization of novel SU($\mathcal{N}>2$) quantum magnetism. △ Less

Submitted 2 November, 2018; v1 submitted 18 January, 2018; originally announced January 2018.

Comments: 10 pages, 9 figures

Journal ref: Phys. Rev. Lett. 121, 225303 (2018)

Spatial Adiabatic Passage of Massive Quantum Particles

Authors: Shintaro Taie, Tomohiro Ichinose, Hideki Ozawa, Yoshiro Takahashi

Abstract: By adiabatically manipulating tunneling amplitudes of cold atoms in a periodic potential with a multiple sublattice structure, we are able to coherently transfer atoms from a sublattice to another without populating the intermediate sublattice, which can be regarded as a spatial analogue of stimulated Raman adiabatic passage. A key is the existence of dark eigenstates forming a flat band in a Lieb… ▽ More By adiabatically manipulating tunneling amplitudes of cold atoms in a periodic potential with a multiple sublattice structure, we are able to coherently transfer atoms from a sublattice to another without populating the intermediate sublattice, which can be regarded as a spatial analogue of stimulated Raman adiabatic passage. A key is the existence of dark eigenstates forming a flat band in a Lieb-type optical lattice. We also successfully observe a matter-wave analogue of Autler-Townes doublet using the same setup. This work shed light on a novel kind of coherent control of cold atoms in optical potentials. △ Less

Submitted 3 August, 2017; originally announced August 2017.

Comments: 6 pages, 4 figures

Journal ref: Nature Communications 11, 257 (2020)

Feshbach-Resonance-Enhanced Coherent Atom-Molecule Conversion with Ultra-Narrow Photoassociation Resonance

Authors: Shintaro Taie, Shunsuke Watanabe, Tomohiro Ichinose, Yoshiro Takahashi

Abstract: We reveal the existence of high-density Feshbach resonances in the collision between the ground and metastable states of $^{171}$Yb and coherently produce the associated Feshbach molecules by photoassociation. The extremely small transition rate is overcome by the enhanced Franck-Condon factor of the weakly bound Feshbach molecule, allowing us to observe Rabi oscillations with long decay time betw… ▽ More We reveal the existence of high-density Feshbach resonances in the collision between the ground and metastable states of $^{171}$Yb and coherently produce the associated Feshbach molecules by photoassociation. The extremely small transition rate is overcome by the enhanced Franck-Condon factor of the weakly bound Feshbach molecule, allowing us to observe Rabi oscillations with long decay time between an atom pair and a molecule in an optical lattice. We also perform the precision measurement of the binding energies, which characterizes the observed resonances. The ultra-narrow photoassociation will be a basis for practical implementation of optical Feshbach resonances. △ Less

Submitted 6 September, 2015; originally announced September 2015.

Comments: 7 pages, 7 figures

Journal ref: Phys. Rev. Lett. 116, 043202 (2016)

Topological Thouless Pumping of Ultracold Fermions

Authors: Shuta Nakajima, Takafumi Tomita, Shintaro Taie, Tomohiro Ichinose, Hideki Ozawa, Lei Wang, Matthias Troyer, Yoshiro Takahashi

Abstract: A gas of electrons in a one-dimensional periodic potential can be transported even in the absence of a voltage bias if the potential is modulated slowly and periodically in time. Remarkably, the transferred charge per cycle is only sensitive to the topology of the path in parameter space. Although this so-called Thouless charge pump has first been proposed more than thirty years ago, it has not ye… ▽ More A gas of electrons in a one-dimensional periodic potential can be transported even in the absence of a voltage bias if the potential is modulated slowly and periodically in time. Remarkably, the transferred charge per cycle is only sensitive to the topology of the path in parameter space. Although this so-called Thouless charge pump has first been proposed more than thirty years ago, it has not yet been realized. Here we report the first demonstration of topological Thouless pumping using ultracold atoms in a dynamically controlled optical superlattice. We observe a shift of the atomic cloud as a result of pumping and extract the topological invariance of the pumping process from this shift. We demonstrate the topological nature of the Thouless pump by varying the topology of the pumping path and verify that the topological pump indeed works in the quantum region by varying speed and temperature. △ Less

Submitted 22 June, 2020; v1 submitted 8 July, 2015; originally announced July 2015.

Comments: 15 pages, 15 figures

Journal ref: Nature Physics 12, 296-300 (2016)

Coherent driving and freezing of bosonic matter wave in an optical Lieb lattice

Authors: Shintaro Taie, Hideki Ozawa, Tomohiro Ichinose, Takuei Nishio, Shuta Nakajima, Yoshiro Takahashi

Abstract: While kinetic energy of a massive particle generally has quadratic dependence on its momentum, a flat, dispersionless energy band is realized in crystals with specific lattice structures. Such macroscopic degeneracy causes the emergence of localized eigenstates and has been a key concept in the context of itinerant ferromagnetism. Here we report the realization of a "Lieb lattice" configuration wi… ▽ More While kinetic energy of a massive particle generally has quadratic dependence on its momentum, a flat, dispersionless energy band is realized in crystals with specific lattice structures. Such macroscopic degeneracy causes the emergence of localized eigenstates and has been a key concept in the context of itinerant ferromagnetism. Here we report the realization of a "Lieb lattice" configuration with an optical lattice, which has a flat energy band as the first excited state. Our optical lattice potential possesses various degrees of freedom about its manipulation, which enables coherent transfer of a Bose-Einstein condensate into the flat band. In addition to measuring lifetime of the flat band population for different tight-binding parameters, we investigate the inter-sublattice dynamics of the system by projecting the sublattice population onto the band population. This measurement clearly shows the formation of the localized state with the specific sublattice decoupled in the flat band, and even detects the presence of flat-band breaking perturbations, resulting in the delocalization. Our results will open up the possibilities of exploring physics of flat band with a highly controllable quantum system. △ Less

Submitted 26 November, 2015; v1 submitted 1 June, 2015; originally announced June 2015.

Comments: 13 pages, 9 figures. v2: Title changed, 1 reference corrected

Journal ref: Sci. Adv. 1, e1500854 (2015)

An SU(N) Mott insulator of an atomic Fermi gas realized by large-spin Pomeranchuk cooling

Authors: Shintaro Taie, Rekishu Yamazaki, Seiji Sugawa, Yoshiro Takahashi

Abstract: The Hubbard model, containing only the minimum ingredients of nearest neighbor hopping and on-site interaction for correlated electrons, has succeeded in accounting for diverse phenomena observed in solid-state materials. One of the interesting extensions is to enlarge its spin symmetry to SU(N>2), which is closely related to systems with orbital degeneracy. Here we report a successful formation o… ▽ More The Hubbard model, containing only the minimum ingredients of nearest neighbor hopping and on-site interaction for correlated electrons, has succeeded in accounting for diverse phenomena observed in solid-state materials. One of the interesting extensions is to enlarge its spin symmetry to SU(N>2), which is closely related to systems with orbital degeneracy. Here we report a successful formation of the SU(6) symmetric Mott insulator state with an atomic Fermi gas of ytterbium (173Yb) in a three-dimensional optical lattice. Besides the suppression of compressibility and the existence of charge excitation gap which characterize a Mott insulating phase, we reveal an important difference between the cases of SU(6) and SU(2) in the achievable temperature as the consequence of different entropy carried by an isolated spin. This is analogous to Pomeranchuk cooling in solid 3He and will be helpful for investigating exotic quantum phases of SU(N) Hubbard system at extremely low temperatures. △ Less

Submitted 23 August, 2012; originally announced August 2012.

Comments: 20 pages, 6 figures, to appear in Nature Physics

Journal ref: Nature Physics, 8, 825 (2012)

Bose-Einstein condensate in gases of rare atomic species

Authors: Seiji Sugawa, Rekishu Yamazaki, Shintaro Taie, Yoshiro Takahashi

Abstract: We report on the successful extension of production of Bose-Einstein Condensate (BEC) to rare species. Despite its low natural abundance of 0.13%, $^{168}$Yb is directly evaporatively cooled down to BEC. Our successful demonstration encourages attempts to obtain quantum gases of radioactive atoms, which extends the possibility of quantum many-body physics and precision measurement. Moreover, a sta… ▽ More We report on the successful extension of production of Bose-Einstein Condensate (BEC) to rare species. Despite its low natural abundance of 0.13%, $^{168}$Yb is directly evaporatively cooled down to BEC. Our successful demonstration encourages attempts to obtain quantum gases of radioactive atoms, which extends the possibility of quantum many-body physics and precision measurement. Moreover, a stable binary mixture of $^{168}$Yb BEC and $^{174}$Yb BEC is successfully formed. △ Less

Submitted 1 July, 2011; originally announced July 2011.

Comments: 5 pages, 3 figures. Accepted for Phys. Rev. A

Journal ref: Phys. Rev. A 84, 011610(R) (2011)

Interaction and filling induced quantum phases of dual Mott insulators of bosons and fermions

Authors: Seiji Sugawa, Kensuke Inaba, Shintaro Taie, Rekishu Yamazaki, Makoto Yamashita, Yoshiro Takahashi

Abstract: Many-body effects are at the very heart of diverse phenomena found in condensed-matter physics. One striking example is the Mott insulator phase where conductivity is suppressed as a result of a strong repulsive interaction. Advances in cold atom physics have led to the realization of the Mott insulating phases of atoms in an optical lattice, mimicking the corresponding condensed matter systems. H… ▽ More Many-body effects are at the very heart of diverse phenomena found in condensed-matter physics. One striking example is the Mott insulator phase where conductivity is suppressed as a result of a strong repulsive interaction. Advances in cold atom physics have led to the realization of the Mott insulating phases of atoms in an optical lattice, mimicking the corresponding condensed matter systems. Here, we explore an exotic strongly-correlated system of Interacting Dual Mott Insulators of bosons and fermions. We reveal that an inter-species interaction between bosons and fermions drastically modifies each Mott insulator, causing effects that include melting, generation of composite particles, an anti-correlated phase, and complete phase-separation. Comparisons between the experimental results and numerical simulations indicate intrinsic adiabatic heating and cooling for the attractively and repulsively interacting dual Mott Insulators, respectively. △ Less

Submitted 3 December, 2010; v1 submitted 19 November, 2010; originally announced November 2010.

Journal ref: Nature Physics 7, 642-648 (2011)

Realization of SU(2)*SU(6) Fermi System

Authors: Shintaro Taie, Yosuke Takasu, Seiji Sugawa, Rekishu Yamazaki, Takuya Tsujimoto, Ryo Murakami, Yoshiro Takahashi

Abstract: We report the realization of a novel degenerate Fermi mixture with an SU(2)*SU(6) symmetry in a cold atomic gas. We successfully cool the mixture of the two fermionic isotopes of ytterbium 171Yb with the nuclear spin I=1/2 and 173Yb with I=5/2 below the Fermi temperature T_ F as 0.46T_F for 171Yb and 0.54T_F for 173Yb. The same scattering lengths for different spin components make this mixture fea… ▽ More We report the realization of a novel degenerate Fermi mixture with an SU(2)*SU(6) symmetry in a cold atomic gas. We successfully cool the mixture of the two fermionic isotopes of ytterbium 171Yb with the nuclear spin I=1/2 and 173Yb with I=5/2 below the Fermi temperature T_ F as 0.46T_F for 171Yb and 0.54T_F for 173Yb. The same scattering lengths for different spin components make this mixture featured with the novel SU(2)*SU(6) symmetry. The nuclear spin components are separately imaged by exploiting an optical Stern-Gerlach effect. In addition, the mixture is loaded into a 3D optical lattice to implement the SU(2)*SU(6) Hubbard model. This mixture will open the door to the study of novel quantum phases such as a spinor Bardeen-Cooper-Schrieffer-like fermionic superfluid. △ Less

Submitted 21 May, 2010; v1 submitted 20 May, 2010; originally announced May 2010.

Comments: 4 pages, 5 figures V2: revised references

Journal ref: PRL 105, 190401 (2010)

Nanometer-scale spatial modulation of an inter-atomic interaction in a Bose-Einstein condensate

Authors: Rekishu Yamazaki, Shintaro Taie, Seiji Sugawa, Yoshiro Takahashi

Abstract: We demonstrate nanometer-scale spatial control of inter-atomic interactions in a Bose-Einstein condensate of ytterbium(Yb). A pulsed optical standing wave, tuned near an optical Feshbach resonance varies the s-wave scattering length continuously across the standing wave pattern. The modulated mean-field energy with a spatial period of every 278 nm is monitored by a diffraction pattern in a time-of… ▽ More We demonstrate nanometer-scale spatial control of inter-atomic interactions in a Bose-Einstein condensate of ytterbium(Yb). A pulsed optical standing wave, tuned near an optical Feshbach resonance varies the s-wave scattering length continuously across the standing wave pattern. The modulated mean-field energy with a spatial period of every 278 nm is monitored by a diffraction pattern in a time-of-flight image. We observe a wide scattering length control of up to 160 nm. The demonstrated spatial modulation of the scattering length proves that the high resolution control of atomic interactions is possible. △ Less

Submitted 19 May, 2010; originally announced May 2010.

A Mott Insulator of Ultracold Alkaline-Earth-Like Atoms

Authors: Takeshi Fukuhara, Seiji Sugawa, Masahito Sugimoto, Shintaro Taie, Yoshiro Takahashi

Abstract: The transition from a superfluid to a Mott insulator (MI) phase has been observed in a Bose-Einstein condensate (BEC) of ytterbium (Yb) atoms in an optical lattice. An all-optically produced BEC of 174Yb atoms was loaded into three-dimensional optical lattices produced by a 532 nm laser beam. The interference pattern was measured after releasing the quantum gas from the trapping potential. As in… ▽ More The transition from a superfluid to a Mott insulator (MI) phase has been observed in a Bose-Einstein condensate (BEC) of ytterbium (Yb) atoms in an optical lattice. An all-optically produced BEC of 174Yb atoms was loaded into three-dimensional optical lattices produced by a 532 nm laser beam. The interference pattern was measured after releasing the quantum gas from the trapping potential. As increasing the optical lattice depth, we observed the disappearance of the interference patterns, which is a signature of entering the MI regime. This result is an important step into studies by using a combination of the MI state and the ultranarrow optical transition of ultracold alkaline-earth-like atoms. △ Less

Submitted 19 January, 2009; v1 submitted 15 January, 2009; originally announced January 2009.

Comments: 4 pages, 3 figures

Journal ref: Phys. Rev. A 79, 041604(R) (2009)