Jing Zhang

Publications (10)10.96 Total impact

• Article: Radio-frequency spectroscopy of a strongly interacting spin-orbit coupled Fermi gas

  Zhengkun Fu, Lianghui Huang, Zengming Meng, Pengjun Wang, Xia-Ji Liu, Han Pu, Hui Hu, Jing Zhang
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  ABSTRACT: We investigate experimentally and theoretically radio-frequency spectroscopy and pairing of a spin-orbit-coupled Fermi gas of $^{40}$K atoms near a Feshbach resonance at $B_{0}=202.2$ G. Experimentally, the integrated spectroscopy is measured, showing characteristic blue and red shifts in the atomic and molecular responses, respectively, with increasing spin-orbit coupling. Theoretically, a smooth transition from atomic to molecular responses in the momentum-resolved spectroscopy is predicted, with a clear signature of anisotropic pairing at and below resonance. Our many-body prediction agrees qualitatively well with the observed spectroscopy near the Feshbach resonance.
  03/2013;
• Article: Momentum-resolved Raman spectroscopy of bound molecules in ultracold Fermi gas

  Zhengkun Fu, Pengjun Wang, Lianghui Huang, Zengming Meng, Jing Zhang
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  ABSTRACT: The binding energy of Feshbach molecules from a two component Fermi gas of $^{40}$K atoms has been experimentally measured with the momentum-resolved Raman spectroscopy. Comparing with the radio-frequency spectroscopy, in the present experiment the signal of unpaired (free atoms) and the bound molecules can be directly observed and the binding energy can be simultaneously determined in a single running experiment. The energy-momentum dispersion spectra of the strongly interacting ultracold Fermi gas in BEC side are also measured and reconstructed. The present experimental technology of the momentum-resolved Raman spectroscopy can be easily extended to perform spatially momentum-resolved Raman spectroscopy and to obtain the response spectra of a homogeneous system in the local density approximation.
  08/2012;
• Article: Momentum-resolved Raman spectroscopy of non-interacting ultracold Fermi gas

  Pengjun Wang, Zhengkun Fu, Lianghui Huang, Jing Zhang
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  ABSTRACT: We report the experiment on probing the one-body spectral function in a trapped non-interacting $^{40}$K Fermi gas by means of the momentum-resolved Raman spectroscopy The experimental result is in good agreement with the expected quadratic dispersion in the non-interacting regime. Through the comparison with the radio-frequency spectrum, we found that the Raman spectrum shows some new characteristics.
  05/2012;
• Article: Spin-Orbit Coupled Degenerate Fermi Gases

  Pengjun Wang, Zeng-Qiang Yu, Zhengkun Fu, Jiao Miao, Lianghui Huang, Shijie Chai, Hui Zhai, Jing Zhang
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  ABSTRACT: Spin-orbit coupling plays an increasingly important role in the modern condensed matter physics. For instance, it gives birth to topological insulators and topological superconductors. Quantum simulation of spin-orbit coupling using ultracold Fermi gases will offer opportunities to study these new phenomena in a more controllable setting. Here we report the first experimental study of a spin-orbit coupled Fermi gas. We observe spin dephasing in spin dynamics and momentum distribution asymmetry in the equilibrium state as hallmarks of spin-orbit coupling. We also observe evidences of Lifshitz transition where the topology of Fermi surfaces change. This serves as an important first step toward finding Majorana fermions in this system.
  04/2012;
• Source

  Available from: ArXiv

  Article: Bose-Einstein Condensate in a light-induced vector potential using the 1064 $nm$ optical dipole trap lasers

  Zhengkun Fu, Pengjun Wang, Shijie Chai, Lianghui Huang, Jing Zhang
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  ABSTRACT: We present a simple experiment of creating an effective vector gauge potential for Bose-Einstein condensed $^{87}$Rb in the F=2 hyperfine ground state using two crossed 1064 $nm$ optical dipole trap lasers as the Raman beams. Due to the far-detuning from the single-photon resonance with the electronically excited state, the spontaneous emission is strongly reduced, at the same time, the moderate strength of the Raman coupling still can be achieved. The atoms at the far detuning of the Raman coupling are loaded adiabatically into the dressed states by ramping the homogeneous bias magnetic field to resonance and the different energy dressed states are studied. This experiment is easily extended to produce synthetic magnetic or electric field from a spatial or time dependence of the effective vector potential.
  06/2011;
• Source

  Available from: E. W. Hagley

  Article: Observation of collective atomic recoil motion in a degenerate fermion gas.

  Pengjun Wang, L Deng, E W Hagley, Zhengkun Fu, Shijie Chai, Jing Zhang
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  ABSTRACT: We demonstrate collective atomic recoil motion with a dilute, ultracold, degenerate fermion gas in a single spin state. By utilizing an adiabatically decompressed magnetic trap with an aspect ratio different from that of the initial trap, a momentum-squeezed fermion cloud is achieved. With a single pump pulse of the proper polarization, we observe, for the first time, multiple wave-mixing processes that result in distinct collective atomic recoil motion modes in a degenerate fermion cloud. Contrary to the case with Bose condensates, no pump-laser detuning asymmetry is present.
  Physical Review Letters 05/2011; 106(21):210401. · 7.37 Impact Factor
• Source

  Available from: E. W. Hagley

  Article: Observation of collective atomic recoil motion in a momentum-squeezed, ultra-cold, degenerate fermion gas

  Pengjun Wang, L Deng, E. W. Hagley, Zhengkun Fu, Shijie Chai, Jing Zhang
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  ABSTRACT: We demonstrate clear collective atomic recoil motion in a dilute, momentum-squeezed, ultra-cold degenerate fermion gas by circumventing the effects of Pauli blocking. Although gain from bosonic stimulation is necessarily absent because the quantum gas obeys Fermi-Dirac statistics, collective atomic recoil motion from the underlying wave-mixing process is clearly visible. With a single pump pulse of the proper polarization, we observe two mutually-perpendicular wave-mixing processes occurring simultaneously. Our experiments also indicate that the red-blue pump detuning asymmetry observed with Bose-Einstein condensates does not occur with fermions.
  06/2010;
• Source

  Available from: ArXiv

  Article: Triply-resonant Optical Parametric Oscillator by Four-wave Mixing with Rubidium Vapor inside an Optical Cavity

  Xudong Yu, Min Xiao, Jing Zhang
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  ABSTRACT: We present an experimental demonstration of simultaneous above-threshold oscillations of the Stokes and anti-Stokes fields together with the single pumping beam with rubidium atoms inside an optical standing-wave cavity. The triple resonant conditions can be achieved easily by making use of the large dispersions due to two-photon transitions in the three-level atomic system. This work provides a way to achieve high efficient nonlinear frequency conversion and the generated bright Stokes and anti-Stokes cavity output beams are potential resource for applications in quantum information science. Comment: Appear in Appl. Phys. Lett
  01/2010;
• Source

  Available from: sxu.cn

  Article: Transport of Bose-Einstein condensate in QUIC trap and separation of trapping spin states.

  Dezhi Xiong, Pengjun Wang, Zhengkun Fu, Jing Zhang
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  ABSTRACT: We have studied the locomotion track of (87)Rb Bose-Einstein condensate during decompressing the trap into the center of the glass cell in a quadrupole-Ioffe configuration trap. In order to change the position of the BEC, the current in the quadrupole coils is reduced while the current in the Ioffe coil keeps constant. Because of the strongly reduced trap frequencies of the moved trap, the BEC considerably sags down due to the gravity. Thus an inflexion point exists in the process of moving BEC. When rubidium atoms go over the inflexion point, they cannot keep in balance under the gravity and the force provided by a magnetic field, and flow downward and towards Ioffe coil. By utilizing this effect, the trapped atoms with the spin state |F = 2,mF = 1>, which are left over in the BEC, can be separated from the BEC of |F = 2,mF = 2> state.
  Optics Express 01/2010; 18(2):1649-56. · 3.59 Impact Factor
• Source

  Available from: ArXiv

  Article: Multi-normal-mode splitting of a cavity in the presence of atoms -- towards the superstrong coupling regime

  Xudong Yu, Dezhi Xiong, Haixia Chen, Pengjun Wang, Min Xiao, Jing Zhang
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  ABSTRACT: Multi-normal-mode splitting peaks are experimentally observed in a system with Doppler-broadened two-level atoms inside a relatively long optical cavity. In this system, the atoms-cavity interaction can reach the ``superstrong coupling" condition with atoms-cavity coupling strength $g\sqrt{N}$ to be near or larger than the cavity free-spectral range $\Delta_{FSR}$. In such case, normal-mode splitting can occur in many cavity longitudinal modes to generate the multi-normal-mode splitting peaks, which can be well explained by the linear dispersion enhancement due to the largely increased atomic density in the cavity. Many new interesting phenomena might come out of this superstrong atoms-cavity coupling regime. Comment: 4 pages, 5 figures. appear in Phys. Rev. A
  06/2009;