arXiv:1110.0650 · Physical Review Letters

Optical Control of Feshbach Resonances in Fermi Gases Using Molecular Dark States

Haibin Wu, John E. Thomas

Published Jan 4, 2012• 44 citations

Abstract

We propose a general method for optical control of magnetic Feshbach resonances in ultracold atomic gases with more than one molecular state in an energetically closed channel. Using two optical frequencies to couple two states in the closed channel, inelastic loss arising from spontaneous emission is greatly suppressed by destructive quantum interference at the two-photon resonance, i.e., dark-state formation, while the scattering length is widely tunable by varying the frequencies and/or intensities of the optical fields. This technique is of particular interest for a two-component atomic Fermi gas, which is stable near a Feshbach resonance.

DOI: 10.1103/physrevlett.108.010401

Related papers

Optical control of the scattering length and effective range for magnetically tunable Feshbach resonances in ultracold gases

Haibin Wu, John E. Thomas

arXiv:1211.4556Physical Review ADec 20, 201232 citations

Optical Control of Magnetic Feshbach Resonances by Closed-Channel Electromagnetically Induced Transparency

Arunkumar Jagannathan, N. Arunkumar, J. A. Joseph +1 more

arXiv:1511.01403Physical Review LettersFeb 17, 201640 citations

Realizing Fulde-Ferrell Superfluids via a Dark-State Control of Feshbach Resonances

Lianyi He, Hui Hu, Xia-Ji Liu

arXiv:1705.04830Physical Review LettersJan 25, 201820 citations

Non-Equilbrium Fermi Gases

John E. Thomas

Feb 2, 20160 citations

Optical Feshbach resonances through a molecular dark state: Efficient manipulation of p -wave resonances in fermionic Yb171 atoms

Subrata Saha, Arpita Rakshit, Debashree Chakraborty +2 more

arXiv:1405.1674Physical Review AJul 1, 20148 citations

Optical control of a magnetic Feshbach resonance in an ultracold Fermi gas

Zhengkun Fu, Pengjun Wang, Lianghui Huang +3 more

arXiv:1306.0395Physical Review AOct 9, 201336 citations

arXiv:1110.0650 · Physical Review Letters

Optical Control of Feshbach Resonances in Fermi Gases Using Molecular Dark States

Haibin Wu, John E. Thomas

Published Jan 4, 2012• 44 citations

arXiv HTML PDF

Abstract

DOI: 10.1103/physrevlett.108.010401

Related papers

Optical control of the scattering length and effective range for magnetically tunable Feshbach resonances in ultracold gases

Haibin Wu, John E. Thomas

We describe two-field optical techniques to control interactions in Feshbach resonances for two-body scattering in ultracold gases. These techniques create a molecular dark state in the closed channel of a magnetically tunable Feshbach resonance, greatly suppressing optical scattering compared to single optical field methods. The dark-state method enables control of the effective range, by creating narrow features that modify the energy dependence of the scattering phase shift, as well as control of the elastic and inelastic parts of the zero-energy $s$ -wave scattering amplitude. We determine the scattering length and the effective range from an effective range expansion, by calculating the momentum-dependent scattering phase shift from the two-body scattering state.We describe two-field optical techniques to control interactions in Feshbach resonances for two-body scattering in ultracold gases. These techniques create a molecular dark state in the closed channel of a magnetically tunable Feshbach resonance, greatly suppressing optical scattering compared to single optical field methods. The dark-state method enables control of the effective range, by creating narrow features that modify the energy dependence of the scattering phase shift, as well as control of the elastic and inelastic parts of the zero-energy $s$-wave scattering amplitude. We determine the scattering length and the effective range from an effective range expansion, by calculating the momentum-dependent scattering phase shift from the two-body scattering state.

arXiv:1211.4556Physical Review ADec 20, 201232 citations

Optical Control of Magnetic Feshbach Resonances by Closed-Channel Electromagnetically Induced Transparency

Arunkumar Jagannathan, N. Arunkumar, J. A. Joseph +1 more

We control magnetic Feshbach resonances in an optically trapped mixture of the two lowest hyperfine states of a ^{6}Li Fermi gas, using two optical fields to create a dark state in the closed molecular channel. In the experiments, the narrow Feshbach resonance is tuned by up to 3 G. For the broad resonance, the spontaneous lifetime is increased to 0.4 s at the dark-state resonance, compared to 0.5 ms for single-field tuning. We present a new model of light-induced loss spectra, employing continuum-dressed basis states, which agrees in shape and magnitude with loss measurements for both broad and narrow resonances. Using this model, we predict the trade-off between tunability and loss for the broad resonance in ^{6}Li, showing that our two-field method substantially reduces the two-body loss rate compared to single-field methods for the same tuning range.We control magnetic Feshbach resonances in an optically trapped mixture of the two lowest hyperfine states of a ^{6}Li Fermi gas, using two optical fields to create a dark state in the closed molecular channel. In the experiments, the narrow Feshbach resonance is tuned by up to 3 G. For the broad resonance, the spontaneous lifetime is increased to 0.4 s at the dark-state resonance, compared to 0.5 ms for single-field tuning. We present a new model of light-induced loss spectra, employing continuum-dressed basis states, which agrees in shape and magnitude with loss measurements for both broad and narrow resonances. Using this model, we predict the trade-off between tunability and loss for the broad resonance in ^{6}Li, showing that our two-field method substantially reduces the two-body loss rate compared to single-field methods for the same tuning range.

arXiv:1511.01403Physical Review LettersFeb 17, 201640 citations

Realizing Fulde-Ferrell Superfluids via a Dark-State Control of Feshbach Resonances

Lianyi He, Hui Hu, Xia-Ji Liu

We propose that the long-sought Fulde-Ferrell superfluidity with nonzero momentum pairing can be realized in ultracold two-component Fermi gases of ^{40}K or ^{6}Li atoms by optically tuning their magnetic Feshbach resonances via the creation of a closed-channel dark state with a Doppler-shifted Stark effect. In this scheme, two counterpropagating optical fields are applied to couple two molecular states in the closed channel to an excited molecular state, leading to a significant violation of Galilean invariance in the dark-state regime and hence to the possibility of Fulde-Ferrell superfluidity. We develop a field theoretical formulation for both two-body and many-body problems and predict that the Fulde-Ferrell state has remarkable properties, such as anisotropic single-particle dispersion relation, suppressed superfluid density at zero temperature, anisotropic sound velocity, and rotonic collective mode. The latter two features can be experimentally probed using Bragg spectroscopy, providing a smoking-gun proof of Fulde-Ferrell superfluidity.We propose that the long-sought Fulde-Ferrell superfluidity with nonzero momentum pairing can be realized in ultracold two-component Fermi gases of ^{40}K or ^{6}Li atoms by optically tuning their magnetic Feshbach resonances via the creation of a closed-channel dark state with a Doppler-shifted Stark effect. In this scheme, two counterpropagating optical fields are applied to couple two molecular states in the closed channel to an excited molecular state, leading to a significant violation of Galilean invariance in the dark-state regime and hence to the possibility of Fulde-Ferrell superfluidity. We develop a field theoretical formulation for both two-body and many-body problems and predict that the Fulde-Ferrell state has remarkable properties, such as anisotropic single-particle dispersion relation, suppressed superfluid density at zero temperature, anisotropic sound velocity, and rotonic collective mode. The latter two features can be experimentally probed using Bragg spectroscopy, providing a smoking-gun proof of Fulde-Ferrell superfluidity.

arXiv:1705.04830Physical Review LettersJan 25, 201820 citations

Non-Equilbrium Fermi Gases

John E. Thomas

Abstract : During this period, we made important breakthroughs in the optical control of two-body interactions in ultra-cold gases. We have studied magnetic Feshbach resonances in an optically-trapped mixture of the two lowest hyperfine states of a 6Li Fermi gas, using two optical fields to create a darkstate in the closed molecular channel. In the experiments, the narrow Feshbach resonance is tuned by up to 3 G. For the broad resonance, thespontaneous lifetime is increased from 0.5 ms for single field tuning to 0.4 s at the dark state resonance, despite the large background scatteringlength.A major breakthrough in our understanding is the experimental verification of a new model of light-induced loss spectra, employing continuum-dressed basis states, which agrees in shape and magnitude with all of our loss measurements for both broad and narrow resonances.Using this model, we show that our method substantially reduces the two-body loss rate compared to single field methods for same tuning range.Abstract : During this period, we made important breakthroughs in the optical control of two-body interactions in ultra-cold gases. We have studied magnetic Feshbach resonances in an optically-trapped mixture of the two lowest hyperfine states of a 6Li Fermi gas, using two optical fields to create a darkstate in the closed molecular channel. In the experiments, the narrow Feshbach resonance is tuned by up to 3 G. For the broad resonance, thespontaneous lifetime is increased from 0.5 ms for single field tuning to 0.4 s at the dark state resonance, despite the large background scatteringlength.A major breakthrough in our understanding is the experimental verification of a new model of light-induced loss spectra, employing continuum-dressed basis states, which agrees in shape and magnitude with all of our loss measurements for both broad and narrow resonances.Using this model, we show that our method substantially reduces the two-body loss rate compared to single field methods for same tuning range.

Feb 2, 20160 citations

Optical Feshbach resonances through a molecular dark state: Efficient manipulation of p -wave resonances in fermionic Yb171 atoms

Subrata Saha, Arpita Rakshit, Debashree Chakraborty +2 more

In a recent experiment by Yamazaki et al. [Phys. Rev. A 87, 010704(R) (2013)], a $p$ -wave optical Feshbach resonance in fermionic $^{171}\mathrm{Yb}$ atoms using purely long-range molecular excited states has been demonstrated. We show theoretically that, if two purely long-range excited states of $^{171}\mathrm{Yb}$ are coupled to the ground-state continuum of scattering states with two lasers, then it is possible to significantly suppress photoassociative atom loss by a dark resonance in the excited states. We present a general theoretical framework for creating a dark state in an electronically excited molecular potential for the purpose of increasing the efficiency of the optical Feshbach resonance. This can be accomplished by properly adjusting the relative intensity, phase, polarizations, and frequency detunings of two lasers. We present selected numerical results for atom-loss spectra and $p$ -wave elastic- and inelastic-scattering cross sections of $^{171}\mathrm{Yb}$ atoms to illustrate the effects of the molecular dark state on the optical Feshbach resonance.In a recent experiment by Yamazaki et al. [Phys. Rev. A 87, 010704(R) (2013)], a $p$-wave optical Feshbach resonance in fermionic $^{171}\mathrm{Yb}$ atoms using purely long-range molecular excited states has been demonstrated. We show theoretically that, if two purely long-range excited states of $^{171}\mathrm{Yb}$ are coupled to the ground-state continuum of scattering states with two lasers, then it is possible to significantly suppress photoassociative atom loss by a dark resonance in the excited states. We present a general theoretical framework for creating a dark state in an electronically excited molecular potential for the purpose of increasing the efficiency of the optical Feshbach resonance. This can be accomplished by properly adjusting the relative intensity, phase, polarizations, and frequency detunings of two lasers. We present selected numerical results for atom-loss spectra and $p$-wave elastic- and inelastic-scattering cross sections of $^{171}\mathrm{Yb}$ atoms to illustrate the effects of the molecular dark state on the optical Feshbach resonance.

arXiv:1405.1674Physical Review AJul 1, 20148 citations

Optical control of a magnetic Feshbach resonance in an ultracold Fermi gas

Zhengkun Fu, Pengjun Wang, Lianghui Huang +3 more

We use laser light near resonant with a molecular bound-to-bound transition to control a magnetic Feshbach resonance in ultracold Fermi gases of ${}^{40}$ K atoms. The spectrum of excited molecular states is measured by applying a laser field that couples the ground Feshbach molecular state to electronically excited molecular states. Nine strong bound-to-bound resonances are observed below the ${}^{2}{P}_{1/2}+{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}$ threshold. We use radio-frequency spectroscopy to characterize the laser-dressed bound state near a specific bound-to-bound resonance and show clearly the shift of the magnetic Feshbach resonance using light. The demonstrated technology could be used to modify interatomic interactions with high spatial and temporal resolutions in the crossover regime from a Bose-Einstein condensate to a Bardeen-Cooper-Schrieffer superfluid.We use laser light near resonant with a molecular bound-to-bound transition to control a magnetic Feshbach resonance in ultracold Fermi gases of ${}^{40}$K atoms. The spectrum of excited molecular states is measured by applying a laser field that couples the ground Feshbach molecular state to electronically excited molecular states. Nine strong bound-to-bound resonances are observed below the ${}^{2}{P}_{1/2}+{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}$ threshold. We use radio-frequency spectroscopy to characterize the laser-dressed bound state near a specific bound-to-bound resonance and show clearly the shift of the magnetic Feshbach resonance using light. The demonstrated technology could be used to modify interatomic interactions with high spatial and temporal resolutions in the crossover regime from a Bose-Einstein condensate to a Bardeen-Cooper-Schrieffer superfluid.

arXiv:1306.0395Physical Review AOct 9, 201336 citations

s

-wave scattering amplitude. We determine the scattering length and the effective range from an effective range expansion, by calculating the momentum-dependent scattering phase shift from the two-body scattering state.

In a recent experiment by Yamazaki et al. [Phys. Rev. A 87, 010704(R) (2013)], a

p

-wave optical Feshbach resonance in fermionic

^{171}\mathrm{Yb}

atoms using purely long-range molecular excited states has been demonstrated. We show theoretically that, if two purely long-range excited states of

^{171}\mathrm{Yb}

are coupled to the ground-state continuum of scattering states with two lasers, then it is possible to significantly suppress photoassociative atom loss by a dark resonance in the excited states. We present a general theoretical framework for creating a dark state in an electronically excited molecular potential for the purpose of increasing the efficiency of the optical Feshbach resonance. This can be accomplished by properly adjusting the relative intensity, phase, polarizations, and frequency detunings of two lasers. We present selected numerical results for atom-loss spectra and

p

-wave elastic- and inelastic-scattering cross sections of

^{171}\mathrm{Yb}

atoms to illustrate the effects of the molecular dark state on the optical Feshbach resonance.

We use laser light near resonant with a molecular bound-to-bound transition to control a magnetic Feshbach resonance in ultracold Fermi gases of

{}^{40}

K atoms. The spectrum of excited molecular states is measured by applying a laser field that couples the ground Feshbach molecular state to electronically excited molecular states. Nine strong bound-to-bound resonances are observed below the

{}^{2}{P}_{1/2}+{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}

threshold. We use radio-frequency spectroscopy to characterize the laser-dressed bound state near a specific bound-to-bound resonance and show clearly the shift of the magnetic Feshbach resonance using light. The demonstrated technology could be used to modify interatomic interactions with high spatial and temporal resolutions in the crossover regime from a Bose-Einstein condensate to a Bardeen-Cooper-Schrieffer superfluid.