Tunable flux through a synthetic hall tube of neutral Fermions

Xi-Wang Luo, Jing Zhang, Chuanwei Zhang

Hall tube with a tunable flux is an important geometry for studying quantum Hall physics, but its experimental realization in real space is still challenging. Here, we propose to realize a synthetic Hall tube with tunable flux in a one-dimensional optical lattice with the synthetic ring dimension defined by atomic hyperfine states. We investigate the effects of the flux on the system topology and study its quench dynamics. Utilizing the tunable flux, we show how to realize topological charge pumping. Finally, we show that the recently observed....

Physical Review A. 102, 063327 (2020)

Photoassociation spectroscopy of weakly bound ⁸⁷Rb₂ molecules near the 5P_1/2 + 5S_1/2 threshold by optical Bragg scattering in Bose-Einstein condensates

Khan Sadiq Nawaz,  Liangchao Chen,  Chengdong Mi,  Zengming Meng,  Lianghui Huang,  Pengjun Wang ,  and Jing Zhang

We report the high-resolution photoassociation (PA) spectroscopy of a ⁸⁷Rb Bose-Einstein condensate (BEC) to excited molecular states near the dissociation limit of 5P_1/2 + 5S_1/2 by optical Bragg scattering. Since the detection of optical Bragg scattering in the BEC has a high signal-noise ratio, we obtain the high-resolution PA spectrum of excited molecular states in the range of ±1 GHz near the dissociation limit of 5P_1/2 + 5S_1/2 . We compare the results with the conventional method of trap loss and show that the results agree with each other very well. Many interesting phenomena of excited molecular states are observed, such as light-induced frequency shift and anomalous strong bound molecular lines at the atomic transition from |F = 1> to |F'= 2>. The observed excited molecular states in the range of ±1 GHz near the dissociation limit of 5P_1/2 + 5S_1/2 should help to further improve long-range bound-state models near the dissociation limit....

Physical Review A. 102, 053326 (2020)

Synthesized magnetic field of a sawtooth superradiance lattice in Bose–Einstein condensates

Pengjun Wang , Liangchao Chen , Chengdong Mi , Zengming Meng , Lianghui Huang , Khan Sadiq Nawaz , Han Cai   , Da-Wei Wang , Shi-Yao Zhu and Jing Zhang

Ultracold atoms have become one of the most exciting platforms to synthesize novel condensed matter physics. Here we realize a sawtooth superradiance lattice in Bose–Einstein condensates and investigate its chiral edge currents. Based on one-dimensional superradiance lattice (SL) in standing wave-coupled electromagnetically induced transparency, a far-detuned standing-wave field is introduced to synthesize a magnetic field. The relative spatial phase between the two standing-wave coupling fields introduce a magnetic flux in the sawtooth loop transitions of the lattice. This flux determines the moving direction of excitations created in the SL and results in nonsymmetric reflectivities when the SL is probed in two opposite directions. Our work demonstrates an in situ technique to synthesize and detect artificial gauge field in cold atoms...

npj Quantum Information. 6:18 (2020)

Experimental realization of spin-tensor momentum coupling in ultracold Fermi gases

Donghao Li , Lianghui Huang, Peng Peng, Guoqi Bian, Pengjun Wang, Zengming Meng, Liangchao Chen and Jing Zhang

We experimentally realize spin-tensor momentum coupling (STMC) using three ground Zeeman states coupled by three Raman laser beams in an ultracold atomic system of ⁴⁰K Fermi atoms. This type of STMC consists of two bright-state bands as a spin-orbit coupled spin-1/2 system and one dark-state middle band. Using radio-frequency spin-injection spectroscopy, we investigate the energy band of STMC. It is demonstrated that the middle state is a dark state in the STMC system. The experimental realization of STMC open the door for further exploring exotic quantum matter...

Physical Review A. 102, 013309 (2020)   

Controllable coupled-resonator-induced transparency in a dual-recycled Michelson interferometer

Xudong Yu, Wei Li, Yuanbin Jin, and Jing Zhang

We theoretically and experimentally study the effect of the coupled-resonator-induced transparency in the Michelson interferometer with the dual-recycled configuration, which is equivalent to the adjustable coupled resonator. The coupling strength, corresponding to the splitting of the reflection spectrum and associated with the width of the coupled-resonator-induced transparent window, can be controlled by adjusting the arm lengths, i.e., the relative phase of the interference arms on the 50:50 beam splitter. Thus, this tunability of the coupling strength can be very fast, and the absorptive and dispersive properties can be effectively controlled. This work provides an alternative system for coherent control and storage of an optical field...

Physical Review A. 98, 053854 (2018)   

Universal feature in optical control of a p-wave Feshbach resonance

Peng Peng, Ren Zhang, Lianghui Huang, Donghao Li, Zengming Meng, Pengjun Wang, Hui Zhai, Peng Zhang, and Jing Zhang

We report the experimental results on the optical control of a p-wave Feshbach resonance by utilizing a laser-driven bound-to-bound transition to shift the energy of a closed-channel molecule state. The magnetic field location for the p-wave resonance as a function of laser detuning can be captured by a simple formula with essentially one parameter, which describes how sensitively the resonance depends on the laser detuning. The key result of this work is to demonstrate, both experimentally and theoretically, that the ratio between this parameter for the m = 0 component of the resonance and that for the m = ±1 component, to a large extent, is universal. We also show that this optical control can create intriguing situations where interesting few- and many-body physics can occur, such as a p-wave resonance overlapping with an s-wave resonance or the three components of a p-wave resonance being degenerate...

Physical Review A. 97, 012702 (2018)   

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Observation of Floquet bands in driven spin-orbit-coupled Fermi gases

Lianghui Huang, Peng Peng, Donghao Li, Zengming Meng, Liangchao Chen, Qu, Pengjun Wang, Chuanwei Zhang,and Jing Zhang

Periodicdrivingofaquantumsystemcansignificantlyalteritsenergybandsandevenchangethebandtopology, opening a completely new avenue for engineering novel quantum matter. Although important progress has been made recently in measuring topological properties of Floquet bands in different systems, direct experimental measurement of full Floquet band dispersions and their topology change is still demanding. Here we directly measure Floquet band dispersions in a periodically driven spin-orbit-coupled ultracold Fermi gas using spin- injection radio-frequency spectroscopy. We observe that the Dirac point originating from two-dimensional spin- orbit coupling can be manipulated to emerge at the lowest or highest two dressed bands by fast modulating Raman laser frequencies, demonstrating topological change of Floquet bands. Our work will provide a powerful tool for understanding fundamental Floquet physics as well as engineering exotic topological quantum matter...

Physical Review A. 98, 013615 (2018)   

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Quantum secret sharing among four players using multipartite bound entanglement of an optical field

Yaoyao Zhou, Juan Yu, Zhihui Yan, Xiaojun Jia, Jing Zhang, Changde Xie, and Kunchi Peng

Secret sharing is a conventional technique for realizing secure communications in information networks, where a dealer distributes to n players a secret, which can only be decoded through the cooperation of k (n=2 < k ≤ n) players. In recent years, quantum resources have been employed to enhance security of secret sharing, which has been named quantum secret sharing (QSS). A multipartite bound entanglement (BE) state of an optical field, due to its special entanglement features, can be used in quantum networks to improve security and flexibility of communication.We design and experimentally demonstrate a QSS protocol, where the dealer modulates a secret on a four-partite BE state and then distributes the submodes of the BE state to four spatially separated players...

Physical Review Letters. 121, 150502 (2018)   

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Optically levitated nanosphere with high trapping frequency

YuanBin Jin , XuDong Yu , and Jing Zhang

The optically levitated object is intrinsically isolated from the thermal bath compared with the opto-mechanical oscillator connected to the thermal environment via the cantilever . Thus the limitation of the thermalization and decoherence in- troduced by the cantilever is cancelled. The Q-factor of the system is predicted to approach 10¹² and the system is ex-tremely sensitive to some changes. And it is expected to detect non-Newtonian gravity forces at very small scales, the impact of single air molecules, nanoscale temperature, and magnetic spin resonance. Importantly it can be used to test the fundamental physical problems. If the nano- particle in ultra-high vacuum is cooled down to the quantum ground state, it can produce the quantum macroscopic super- position state and test the decoherence mechanism...

Science China Physics, Mechanics & Astronomy. 11, 114221 (2018)   

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Experimental observation of one-dimensional superradiance lattices in ultracold atoms

Liangchao Chen,Pengjun Wang ,Zengming Meng, Lianghui Huang, Han Cai Da-Wei Wang, Shi-Yao Zhu, and Jing Zhang

We measure the superradiant emission in a one-dimensional (1D) superradiance lattice (SL) in ultracold atoms. Resonantly excited to a superradiant state, the atoms are further coupled to other collectively excited states, which form a 1D SL. The directional emission of one of the superradiant excited states in the 1D SL is measured. The emission spectra depend on the band structure, which can be controlled by the frequency and intensity of the coupling laser fields. This work provides a platform for investigating the collective Lamb shift of resonantly excited superradiant states in Bose-Einstein condensates and paves the way for realizing higher dimensional superradiance lattices...

Physical Review Letters. 120, 193601 (2018)   

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Characterization of squeezed states with controllable coherent light injection at sidebands

Wei Li , YuanBin Jin , and XuDong Yu

The squeezed state was experimentally produced in the four wave mixing process for the first time thirty years ago . Its intrinsic nonclassical property has always attracted the attention of the scientists, and it has also presented an unpredictable application potential in quantum information processing and quantum metrology. For gaining an insight into the quantum state, Bertrand et al.introduced the concept of quantum tomography into quantum me- chanics in 1987. And in 1997, Breitenbach et al.presented the noise distribution of the squeezed states of light fields and reconstructed the quantum states by balanced ho- modyne detection (BHD). If the squeezed state light field has a relatively strong amplitude, BHD is not suitable. Consequently, other approaches have also been studied, such as self-tomography of the twin-beam state and self- tomography of the single-mode squeezed light field with an empty cavity. These approaches enable people to understand the nature of the quantum state...

Science China Physics, Mechanics & Astronomy. 5, 050321 (2017)   

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Enhanced detection of a low-frequency signal by using broad squeezed light and a bichromatic local oscillator

Wei Li, Yuanbin Jin, Xudong Yu and Jing Zhang

We experimentally study a protocol of using the broadband high-frequency squeezed vacuum to detect the low-frequency signal. In this scheme, the lower sideband field of the squeezed light carries the low-frequency modulation signal, and the two strong coherent light fields are applied as the bichromatic local oscillator in the homodyne detection to measure the quantum entanglement of the upper and lower sideband for the broadband squeezed light. The power of one of the local oscillators for detecting the upper sideband can be adjusted to optimize the conditional variance in the low-frequency regime by subtracting the photocurrent of the upper sideband field of the squeezed light from that of the lower sideband field. By means of the quantum correlation of the upper and lower sideband for the broadband squeezed light, the low-frequency signal beyond the standard quantum limit is measured. This scheme is appropriate for enhancing the sensitivity of the low-frequency signal bytheaidofthebroadsqueezedlight,suchasgravitationalwavesdetection,anddoesnotneedtodirectlyproduce the low-frequency squeezing in an optical parametric process...

Physical Review A. 96, 023808 (2017)   

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Experimental observation of a topological band gap opening in ultracold Fermi gases with two-dimensional spin-orbit coupling

Zengming Meng, Lianghui Huang, Peng Peng,Donghao Li,Liangchao Chen, Yong Xu, Chuanwei Zhang,Pengjun Wang,and Jing Zhang

The recent experimental realization of synthetic spin-orbit coupling (SOC) opens a new avenue for exploring novel quantum states with ultracold atoms. However, in experiments for generating twodimensional SOC (e.g., Rashba type), a perpendicular Zeeman field, which opens a band gap at the Dirac point and induces many topological phenomena, is still lacking....

Physical Review Letters. 117, 235304 (2016)    

Experimental realization of two-dimensional synthetic spin-orbit coupling in ultracold Fermi gases

Lianghui Huang, Zengming Meng, Pengjun Wang, Peng Peng, Shao-Liang Zhang, Liangchao Chen, Donghao Li, Qi Zhou, and Jing Zhang

Spin-orbit coupling (SOC) is central to many physical phenomena, including fine structures of atomic spectra and quantum topological matters. Whereas SOC is in general fixed in a physical system, atom-laser interaction provides physicists a unique means to create and control synthetic SOC for ultracold atoms [1].Though significant experimental progresses have been made...

Nature Physics. 12, 540-544 (2016)    

Measurement of the squeezed vacuum state by a bichromatic local oscillator

Wei Li, Xudong Yu, and Jing Zhang,

We present the experimental measurement of a squeezed vacuum state by means of a bichromatic local oscillator (BLO). A pair of local oscillators at
5 MHz around the central frequency ω0 of the fundamental field with equal power are generated by three acousto-optic modulators and phase-locked technology and used as a BLO. The squeezed vacuum light is detected by a phase-sensitive balanced-homodyne detection with a BLO...

Optics Letters. 40, 005299 (2015)   

Dissociation of Feshbach molecules via spin-orbit coupling in ultracold Fermi gases

Lianghui Huang, Pengjun Wang, Peng Peng, Zengming Meng, Liangchao Chen, Peng Zhang, and Jing Zhang,

We study the dissociation of Feshbach molecules in ultracold Fermi gases with spin-orbit (SO) coupling. Since SO coupling can induce a quantum transition between Feshbach molecules and the fully polarized Fermi gas, the Feshbach molecules can be dissociated by the SO coupling. We experimentally realize this type of dissociation in ultracold gases of 40K atoms with SO coupling created by Raman beams...

Physical Review A. 91, 041604 (2015)   

Radio-frequency spectrum of the Feshbach molecular state to deeply bound molecular states in ultracold ⁴⁰K Fermi gases

Lianghui Huang, Pengjun Wang, B P Ruzic, Zhengkun Fu, Zengming Meng, Peng Peng, J L Bohn and Jing Zhang

Spectroscopic measurements are made and obtained for three molecular levels within 50 MHzof the atomic continuum, along with their variation of magnetic field in ultracold ⁴⁰K Fermi gases.Weuse spectroscopic measurements to modify the scattering properties near magnetic Fano–Feshbach resonances with a radio-frequency (RF) field by measuring the loss profile versus magnetic field...

New Journal Of Physics . 17, 033013 (2015)     

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Production of Feshbach molecules induced by spin–orbit coupling in Fermi gases

Zhengkun Fu, Lianghui Huang, Zengming Meng, Pengjun Wang, Long Zhang,Shizhong hang, Hui Zhai, Peng Zhang,and Jing Zhang

In this work we demonstrate a dynamic process in which SO coupling can coherently produce swave Feshbach molecules from a fully polarized Fermi gas, and can induce a coherent oscillation between Feshbach molecules and spin polarized gas. For comparison, we also show that such phenom- ena are absent if the inter-component coupling is momentum-independent....

Nature Physics. 10, 110 (2013)    

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

Zhengkun Fu, Pengjun Wang, Lianghui Huang, Zengming Meng, Hui Hu, and Jing Zhang

We use laser light near-resonant with a molecular bound-to-bound transition to control a magnetic Feshbach resonance in ultracold Fermi gases of ⁴⁰K 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. ...

Physical Review A. 88, 041601 (2013)  

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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, and Jing Zhang

We investigate experimentally and theoretically radio-frequency spectroscopy and pairing of a spin-orbitcoupled Fermi gas of ⁴⁰K atoms near a Feshbach resonance at B0 = 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....

Physical Review A. 87, 053619 (2013)   

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