Cooperative Institute for Research in Environmental Sciences

Xinzhao Chu

Xinzhao Chu

Research Interests

My research goal is to explore unknowns in the atmosphere, space, and beyond. My group works to explore advanced spectroscopy principles and develop new lidar technologies to push detection limits and make new discoveries. By making measurements with unprecedented accuracy, resolution, and coverage, we study the fundamental physical and chemical processes that govern the structures and dynamics of the whole atmosphere, and advance the understanding of the universal processes in the Earth’s space-atmosphere interaction region and how they shape the atmospheres of Earth-like planets. In our quest to develop whole-atmosphere lidar and to explore the unmapped, we also aim to realize the full potential of lidar, making practical use of it to serve the world. 


Current Research

Lidar marathons in Antarctica and plasma-neutral atmosphere coupling

Discoveries of thermospheric neutral iron (Fe) layers (Chu et al., Geophys. Res. Lett., 2011), solar effects on Fe layer bottomside (Yu et al., J. Geophys. Res., 2012), persistent inertia-gravity waves (Chen et al., J. Geophys. Res., 2013), and super-exponential growth of thermal tide amplitude above 100 kilometers (Fong et al., J. Geophys. Res., 2014) by lidar observations in Antarctica are challenging our understanding of electrodynamics, neutral dynamics, chemistry, composition, and energetics in Earth’s geospace environment. CIRES students Zhibin Yu and Weichun Fong in the Chu research group are developing numerical models to study the mechanisms. We achieved initial success, having successfully modeled the thermospheric Fe layers after carefully considering the neutral-plasma coupling and the influences of polar electric field, vertical wind, and aurora activity (see figure). These science discoveries are motivating the atmosphere and space science community with a new initiative, Observatory for Atmosphere Space Interaction Studies (OASIS).

This also has been a year of setting records. The CIRES lidar team set a historic record for lidar observations: a continuous 174 hours of observations from Dec. 29, 2013, to Jan. 6, 2014, in Antarctica. CIRES student Cao Chen set new records, making continuous, sole-operator, 53- and 65-hour lidar observations in the harsh Antarctic winter. CIRES student John Smith and CIRES researcher Wentao Huang achieved lidar signal levels of 2,400 counts per shot at Boulder, Colorado. These long and very high-resolution data sets are invaluable in pushing the envelope of upper atmosphere sciences. Another unprecedented record: CIRES students in the Chu group have won prizes every year from 2009 to 2014 in the Coupling, Energetic, and Dynamics of Atmospheric Regions (CEDAR) Student Poster Competition— most recently Zhibin Yu in 2013 and Weichun Fong in 2014. CIRES researcher Xian Lu won a CEDAR grant as the principal investigator for the first time. Congratulations to these creative students and researchers!

Thermospheric iron (Fe) layers (top) discovered by lidar observations on May 28, 2011, at McMurdo, Antarctica (Chu et al., Geophys. Res. Lett., 2011) have been successfully modeled with a new thermospheric Fe/Fe+ model (middle and bottom) through the coupling between Fe+ and Fe layers in the polar geospace (Yu and Chu, J. Geophys. Res., 2014).

"Members" of the lidar team (from left to right: Cao Chen, Xinzhao Chu, and Jian Zhao) deployed in the summer of 2013–2014 at McMurdo, Antarctica.

CIRES Ph.D. students Cao Chen and Jian Zhao jump up at Arrival Heights Lidar Observatory near McMurdo, Antarctica, to celebrate an extremely successful summer season and Chen's qualification to winter-over in 2014.


Honors and Awards

  • Faculty Early Career Development (CAREER) Award, National Science Foundation
  • Director, Consortium Technology Center for the Consortium of Resonance and Rayleigh Lidars, National Science Foundation

View Publications

  • Zhao, J, XZ Chu, C Chen, X Lu, WC Fong, ZB Yu, RM Jones, BR Roberts and A Dornbrack (2017), Lidar observations of stratospheric gravity waves from 2011 to 2015 at McMurdo (77.84 degrees S, 166.69 degrees E), Antarctica: 1. Vertical wavelengths, periods, and frequency and vertical wave number spectra. J. Geophys. Res.-Atmos. Version: 1 122 (10) 5041-5062, issn: 2169-897X, ids: EY6YT, doi: 10.1002/2016JD026368
  • Chen, C, XZ Chu, J Zhao, BR Roberts, ZB Yu, WC Fong, X Lu and JA Smith (2016), Lidar observations of persistent gravity waves with periods of 3-10h in the Antarctic middle and upper atmosphere at McMurdo (77.83 degrees S, 166.67 degrees E). J. Geophys. Res.-Space Phys. Version: 1 121 (2) 1483-1502, issn: 2169-9380, ids: DH7VN, doi: 10.1002/2015JA022127
  • Smith, JA and XZ Chu (2016), Investigation of a field-widened Mach-Zehnder receiver to extend Fe Doppler lidar wind measurements from the thermosphere to the ground. Appl. Optics Version: 1 55 (6) 1366-1380, issn: 1559-128X, ids: DE2GP, doi: 10.1364/AO.55.001366, PubMed ID: 26906590
  • Abari, CF, XZ Chu, RM Hardesty and J Mann (2015), A reconfigurable all-fiber polarization-diversity coherent Doppler lidar: principles and numerical simulations. Appl. Optics Version: 1 54 (30) 8999-9009, issn: 1559-128X, ids: CU1VZ, doi: 10.1364/AO.54.008999, PubMed ID: 26560390
  • Lu, X, XZ Chu, WC Fong, C Chen, ZB Yu, BR Roberts and AJ McDonald (2015), Vertical evolution of potential energy density and vertical wave number spectrum of Antarctic gravity waves from 35 to 105km at McMurdo (77.8 degrees S, 166.7 degrees E). J. Geophys. Res.-Atmos. Version: 1 120 (7) 2719-2737, issn: 2169-897X, ids: CG6LY, doi: 10.1002/2014JD022751
  • Tsuda, TT, X Chu, T Nakamura, MK Ejiri, TD Kawahara, AS Yukimatu and K Hosokawa (2015), A thermospheric Na layer event observed up to 140km over Syowa Station (69.0 degrees S, 39.6 degrees E) in Antarctica. Geophys. Res. Lett. Version: 1 42 (10) 3647-3653, issn: 0094-8276, ids: CL0KJ, doi: 10.1002/2015GL064101
  • Smith, JA and XZ Chu (2015), High-efficiency receiver architecture for resonance-fluorescence and Doppler lidars. Appl. Optics Version: 1 54 (11) 3173-3184, issn: 1559-128X, ids: CG4FP, doi: 10.1364/AO.54.003173, PubMed ID: 25967301
  • Fong, WC, XZ Chu, X Lu, C Chen, TJ Fuller-Rowell, M Codrescu and AD Richmond (2015), Lidar and CTIPe model studies of the fast amplitude growth with altitude of the diurnal temperature "tides" in the Antarctic winter lower thermosphere and dependence on geomagnetic activity. Geophys. Res. Lett. Version: 1 42 (3) 697-704, issn: 0094-8276, ids: CD8OT, doi: 10.1002/2014GL062784
  • Huang, WT, XZ Chu, CS Gardner, JD Carrillo-Sanchez, WH Feng, JMC Plane and D Nesvorny (2015), Measurements of the vertical fluxes of atomic Fe and Na at the mesopause: Implications for the velocity of cosmic dust entering the atmosphere. Geophys. Res. Lett. Version: 1 42 (1) 169-175, issn: 0094-8276, ids: CA6PE, doi: 10.1002/2014GL062390
  • Gao, Q, XZ Chu, XH Xue, XK Dou, TD Chen and JS Chen (2015), Lidar observations of thermospheric Na layers up to 170km with a descending tidal phase at Lijiang (26.7 degrees N, 100.0 degrees E), China. J. Geophys. Res.-Space Phys. Version: 1 120 (10) 9213-9220, issn: 2169-9380, ids: CY0ZI, doi: 10.1002/2015JA021808
  • Lu, Xian, Cao Chen, Wentao Huang, John A. Smith, Xinzhao Chu, Tao Yuan, Pierre-Dominique Pautet, Mike J. Taylor, Jie Gong and Chihoko Y. Cullens (2015), A coordinated study of 1 h mesoscale gravity waves propagating from Logan to Boulder with CRRL Na Doppler lidars and temperature mapper. Version: 1 JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 120 (19) 10006-10021, issn: 2169-897X, doi: 10.1002/2015JD023604
  • Fong, WC, X Lu, XZ Chu, TJ Fuller-Rowell, ZB Yu, BR Roberts, C Chen, CS Gardner and AJ McDonald (2014), Winter temperature tides from 30 to 110 km at McMurdo (77.8 degrees S, 166.7 degrees E), Antarctica: Lidar observations and comparisons with WAM. J. Geophys. Res.-Atmos. Version: 1 119 (6) 2846-2863, issn: 2169-897X, ids: AH3SV, doi: 10.1002/2013JD020784
  • Huang, WT, XZ Chu, CS Gardner, ZJ Wang, WC Fong, JA Smith and BR Roberts (2013), Simultaneous, common-volume lidar observations and theoretical studies of correlations among Fe/Na layers and temperatures in the mesosphere and lower thermosphere at Boulder Table Mountain (40 degrees N, 105 degrees W), Colorado. J. Geophys. Res.-Atmos. Version: 1 118 (15) 8748-8759, issn: 2169-897X, ids: 213DA, doi: 10.1002/jgrd.50670
  • Friedman, JS, XZ Chu, CGM Brum and X Lu (2013), Observation of a thermospheric descending layer of neutral K over Arecibo. J. Atmos. Sol.-Terr. Phys. Version: 1 104 253-259, issn: 1364-6826, ids: 255IH, doi: 10.1016/j.jastp.2013.03.002
  • Lu, X, XZ Chu, T Fuller-Rowell, LR Chang, WC Fong and ZB Yu (2013), Eastward propagating planetary waves with periods of 1-5 days in the winter Antarctic stratosphere as revealed by MERRA and lidar. J. Geophys. Res.-Atmos. Version: 1 118 (17) 9565-9578, issn: 2169-897X, ids: 232JH, doi: 10.1002/jgrd.50717
  • Chen, C, XZ Chu, AJ McDonald, SL Vadas, ZB Yu, WC Fong and X Lu (2013), Inertia-gravity waves in Antarctica: A case study using simultaneous lidar and radar measurements at McMurdo/Scott Base (77.8 degrees S, 166.7 degrees E). J. Geophys. Res.-Atmos. Version: 1 118 (7) 2794-2808, issn: 2169-897X, ids: 153QT, doi: 10.1002/jgrd.50318
  • Yu, ZB, XZ Chu, WT Huang, WC Fong and BR Roberts (2012), Diurnal variations of the Fe layer in the mesosphere and lower thermosphere: Four season variability and solar effects on the layer bottomside at McMurdo (77.8 degrees S, 166.7 degrees E), Antarctica. J. Geophys. Res.-Atmos. Version: 1 117 , Art. No. D22303, issn: 2169-897X, ids: 043RF, doi: 10.1029/2012JD018079
  • Friedman, JS, D Maldonado-Nieves, I Gonzalez, J Lautenbach, XZ Chu, JA Smith and WT Huang (2012), High spectral resolution test and calibration of an ultra-narrowband Faraday anomalous dispersion optical filter for use in daytime mesospheric resonance Doppler lidar. J. Atmos. Sol.-Terr. Phys. Version: 1 80 187-194, issn: 1364-6826, ids: 953SR, doi: 10.1016/j.jastp.2012.01.017
  • Tan, B, XZ Chu, HL Liu, C Yamashita and JM Russell (2012), Zonal-mean global teleconnection from 15 to 110 km derived from SABER and WACCM. J. Geophys. Res.-Atmos. Version: 1 117 , Art. No. D10106, issn: 2169-897X, ids: 945GC, doi: 10.1029/2011JD016750
  • Chu, XZ, ZB Yu, CS Gardner, C Chen and WC Fong (2011), Lidar observations of neutral Fe layers and fast gravity waves in the thermosphere (110-155 km) at McMurdo (77.8 degrees S, 166.7 degrees E), Antarctica. Geophys. Res. Lett. Version: 1 38 , Art. No. L23807, issn: 0094-8276, ids: 864TA, doi: 10.1029/2011GL050016
  • Gardner, CS, XZ Chu, PJ Espy, JMC Plane, DR Marsh and D Janches (2011), Seasonal variations of the mesospheric Fe layer at Rothera, Antarctica (67.5 degrees S, 68.0 degrees W). J. Geophys. Res.-Atmos. Version: 1 116 , Art. No. D02304, issn: 2169-897X, ids: 710OC, doi: 10.1029/2010JD014655
  • Chu, XZ, WT Huang, WC Fong, ZB Yu, ZJ Wang, JA Smith and CS Gardner (2011), First lidar observations of polar mesospheric clouds and Fe temperatures at McMurdo (77.8 degrees S, 166.7 degrees E), Antarctica. Geophys. Res. Lett. Version: 1 38 , Art. No. L16810, issn: 0094-8276, ids: 813LQ, doi: 10.1029/2011GL048373
  • Yamashita, C, HL Liu and XZ Chu (2010), Responses of mesosphere and lower thermosphere temperatures to gravity wave forcing during stratospheric sudden warming. Geophys. Res. Lett. Version: 1 37 , Art. No. L09803, issn: 0094-8276, ids: 593RM, doi: 10.1029/2009GL042351
  • Xu, L, XO Hu, YQ Cheng, SY Guo, ZA Yan and XZ Chu (2010), Simulation of echo-photon counts of a Sodium Doppler Lidar and retrievals of atmospheric parameters. Chinese J. Geophys.-Chinese Ed. Version: 1 53 (7) 1520-1528, issn: 0001-5733, ids: 632NK, doi: 10.3969/j.issn.0001-5733.2010.07.003
  • Yamashita, C, HL Liu and XZ Chu (2010), Gravity wave variations during the 2009 stratospheric sudden warming as revealed by ECMWF-T799 and observations. Geophys. Res. Lett. Version: 1 37 , Art. No. L22806, issn: 0094-8276, ids: 683ML, doi: 10.1029/2010GL045437
  • McDonald, AJ, B Tan and XZ Chu (2010), Role of gravity waves in the spatial and temporal variability of stratospheric temperature measured by COSMIC/FORMOSAT-3 and Rayleigh lidar observations. J. Geophys. Res.-Atmos. Version: 1 115 , Art. No. D19128, issn: 2169-897X, ids: 666BU, doi: 10.1029/2009JD013658
  • Wang, ZJ, ZS Liu, LP Liu, SH Wu, BY Liu, ZG Li and XZ Chu (2010), Iodine-filter-based mobile Doppler lidar to make continuous and full-azimuth-scanned wind measurements: data acquisition and analysis system, data retrieval methods, and error analysis. Appl. Optics Version: 1 49 (36) 6960-6978, issn: 1559-128X, ids: 697FZ, doi: 10.1364/AO.49.006960, PubMed ID: 21173831
  • Smith, JA, XZ Chu, WT Huang and B Tan (2009), Applications of spectral analysis and filter design in laser frequency locking for Na Doppler lidars. Opt. Eng. Version: 1 48 (10) , Art. No. 104301, issn: 0091-3286, ids: 519DW, doi: 10.1117/1.3251080
  • Yamashita, C, XZ Chu, HL Liu, PJ Espy, GJ Nott and WT Huang (2009), Stratospheric gravity wave characteristics and seasonal variations observed by lidar at the South Pole and Rothera, Antarctica. J. Geophys. Res.-Atmos. Version: 1 114 , Art. No. D12101, issn: 2169-897X, ids: 460KP, doi: 10.1029/2008JD011472
  • Friedman, JS, XL Zhang, XZ Chu and JM Forbes (2009), Longitude variations of the solar semidiurnal tides in the mesosphere and lower thermosphere at low latitudes observed from ground and space. J. Geophys. Res.-Atmos. Version: 1 114 , Art. No. D11114, issn: 2169-897X, ids: 458FU, doi: 10.1029/2009JD011763
  • Huang, WT, XZ Chu, J Wiig, B Tan, C Yamashita, T Yuan, J Yue, SD Harrell, CY She, BP Williams, JS Friedman and RM Hardesty (2009), Field demonstration of simultaneous wind and temperature measurements from 5 to 50 km with a Na double-edge magneto-optic filter in a multi-frequency Doppler lidar. Opt. Lett. Version: 1 34 (10) 1552-1554, issn: 0146-9592, ids: 458YB, PubMed ID: 19448818
  • Huang, WT, XZ Chu, BP Williams, SD Harrell, J Wiig and CY She (2009), Na double-edge magneto-optic filter for Na lidar profiling of wind and temperature in the lower atmosphere. Opt. Lett. Version: 1 34 (2) 199-201, issn: 0146-9592, ids: 405IX, doi: 10.1364/OL.34.000199, PubMed ID: 19148254
  • Smith, JA, XZ Chu, WT Huang, J Wiig and AT Brown (2008), LabVIEW-based laser frequency stabilization system with phase-sensitive detection servo loop for Doppler LIDAR applications. Opt. Eng. Version: 1 47 (11) , Art. No. 114201, issn: 0091-3286, ids: 377RH, doi: 10.1117/1.3013257
  • Friedman, JS and XZ Chu (2007), Nocturnal temperature structure in the mesopause region over the Arecibo Observatory (18.35 degrees N, 66.75 degrees W): Seasonal variations. J. Geophys. Res.-Atmos. Version: 1 112 (D14) , Art. No. D14107, issn: 0148-0227, ids: 198AM, doi: 10.1029/2006JD8220
  • Chu, XZ, PJ Espy, GJ Nott, JC Diettrich and CS Gardner (2006), Polar mesospheric clouds observed by an iron Boltzmann lidar at Rothera (67.5 degrees S, 68.0 degrees W), Antarctica from 2002 to 2005: Properties and implications. J. Geophys. Res.-Atmos. Version: 1 111 (D20) , Art. No. D20213, issn: 2169-897X, ids: 103DP, doi: 10.1029/2006JD007086
  • Zhao, Y, MJ Taylor and X Chu (2005), Comparison of simultaneous Na lidar and mesospheric nightglow temperature measurements and the effects of tides on the emission layer heights. J. Geophys. Res.-Atmos. Version: 1 110 (D9) , Art. No. D09S07
  • Franke, SJ, X Chu, AZ Liu and WK Hocking (2005), "Comparison of meteor radar and Na Doppler lidar measurements of winds in the mesopause region above Maui, Hawaii. J. Geophys. Res.-Atmos. Version: 1 110 (D9) , Art. No. D09S02
  • Diettrich, JC, GJ Nott, PJ Espy, GR Swenson, X Chu, MJ Taylor, DM Riggin and DC Fritts (2005), High frequency atmospheric gravity-wave properties using Fe-lidar and OH-imager observations. Geophys. Res. Lett. Version: 1 32 (9) , Art. No. L09801, issn: 0094-8276, ids: 926TF, doi: 10.1029/2004GL021944
  • Gardner, CS, JMC Plane, WL Pan, T Vondrak, BJ Murray and XZ Chu (2005), Seasonal variations of the Na and Fe layers at the South Pole and their implications for the chemistry and general circulation of the polar mesosphere. J. Geophys. Res.-Atmos. Version: 1 110 (D10) , Art. No. D10302, issn: 0148-0227, ids: 932WK, doi: 10.1029/2004JD005670
  • Stevens, MH, RR Meier, XZ Chu, MT DeLand and JMC Plane (2005), Antarctic mesospheric clouds formed from space shuttle exhaust. Geophys. Res. Lett. Version: 1 32 (13) , Art. No. L13810, issn: 0094-8276, ids: 947JL, doi: 10.1029/2005GL023054
  • Chu, XZ, CS Gardner and SJ Franke (2005), Nocturnal thermal structure of the mesosphere and lower thermosphere region at Maui, Hawaii (20.7 degrees N), and Starfire Optical Range, New Mexico (35 degrees N). J. Geophys. Res.-Atmos. Version: 1 110 (D9) , Art. No. D09S03, issn: 0148-0227, ids: 892YD, doi: 10.1029/2004JD004891
  • Plane, JMC, BJ Murray, XZ Chu and CS Gardner (2004), Removal of meteoric iron on polar mesospheric clouds. Science Version: 1 304 (5669) 426-428, issn: 0036-8075, ids: 812NE, doi: 10.1126/science.1093236
  • Chu, XZ, GJ Nott, PJ Espy, CS Gardner, JC Diettrich, MA Clilverd and MJ Jarvis (2004), Lidar observations of polar mesospheric clouds at Rothera, Antarctica (67.5 degrees S, 68.0 degrees W). Geophys. Res. Lett. Version: 1 31 (2) , Art. No. L02114, issn: 0094-8276, ids: 772WV, doi: 10.1029/2003GL018638
  • Chu, XZ, CS Gardner and RG Roble (2003), Lidar studies of interannual, seasonal, and diurnal variations of polar mesospheric clouds at the South Pole. J. Geophys. Res.-Atmos. Version: 1 108 (D8) , Art. No. 8447, issn: 0148-0227, ids: 665GK, doi: 10.1029/2002JD002524
  • Drummond, JD, BW Grime, CS Gardner, AZ Liu, XZ Chu, MC Kelley, C Kruschwitz and TJ Kane (2002), Observations of persistent Leonid meteor trails - 3. The "Glowworm''. J. Geophys. Res.-Space Phys. Version: 1 107 (A8) , Art. No. 1159, issn: 0148-0227, ids: 611HB, doi: 10.1029/2001JA000223
  • Chu, XZ, WL Pan, GC Papen, CS Gardner and JA Gelbwachs (2002), Fe Boltzmann temperature lidar: design, error analysis, and initial results at the North and South Poles. Appl. Optics Version: 1 41 (21) 4400-4410, issn: 0003-6935, ids: 575WU, doi: 10.1364/AO.41.004400
  • Kruschwitz, CA, MC Kelley, CS Gardner, G Swenson, AZ Liu, X Chu, JD Drummond, BW Grime, WT Armstrong, JMC Plane and P Jenniskens (2001), Observations of persistent Leonid meteor trails 2. Photometry and numerical modeling. J. Geophys. Res.-Space Phys. Version: 1 106 (A10) 21525-21541
  • Chu, XZ, CS Gardner and G Papen (2001), Lidar observations of polar mesospheric clouds at South Pole: Diurnal variations. Geophys. Res. Lett. Version: 1 28 (10) 1937-1940, issn: 0094-8276, ids: 431EB, doi: 10.1029/2000GL012525
  • Chu, XZ, CS Gardner and G Papen (2001), Lidar observations of polar mesospheric clouds at South Pole: Seasonal variations. Geophys. Res. Lett. Version: 1 28 (7) 1203-1206, issn: 0094-8276, ids: 415GZ, doi: 10.1029/2000GL012524
  • Gardner, CS, GC Papen, XZ Chu and WL Pan (2001), First lidar observations of middle atmosphere temperatures, Fe densities, and polar mesospheric clouds over the North and South poles. Geophys. Res. Lett. Version: 1 28 (7) 1199-1202, issn: 0094-8276, ids: 415GZ, doi: 10.1029/2000GL012622
  • Drummond, JD, BW Grime, CS Gardner, AZ Liu, XZ Chu and TJ Kane (2001), Observations of persistent Leonid meteor trails 1. Advection of the "diamond ring". J. Geophys. Res.-Space Phys. Version: 1 106 (A10) 21517-21524, issn: 0148-0227, ids: 475XG, doi: 10.1029/2000JA000173
  • Chu, XZ, AZ Liu, G Papen, CS Gardner, M Kelley, J Drummond and R Fugate (2000), Lidar observations of elevated temperatures in bright chemiluminescent meteor trails during the 1998 Leonid shower. Geophys. Res. Lett. Version: 1 27 (13) 1815-1818, issn: 0094-8276, ids: 331LY, doi: 10.1029/2000GL000080
  • Chu, XZ, WL Pan, G Papen, CS Gardner, G Swenson and P Jenniskens (2000), Characteristics of Fe ablation trails observed during the 1998 Leonid meteor shower. Geophys. Res. Lett. Version: 1 27 (13) 1807-1810, issn: 0094-8276, ids: 331LY, doi: 10.1029/1999GL010756
  • Kelley, MC, C Gardner, J Drummond, T Armstrong, A Liu, X Chu, G Papen, C Kruschwitz, P Loughmiller, B Grime and J Engelman (2000), First observations of long-lived meteor trains with resonance lidar and other optical instruments. Geophys. Res. Lett. Version: 1 27 (13) 1811-1814
  • Razvi, MAN, XZ Chu, R Alheit, G Werth and R Blumel (1998), Fractional frequency collective parametric resonances of an ion cloud in a Paul trap. Phys. Rev. A Version: 1 58 (1) R34-R37, issn: 1050-2947, ids: ZZ998, doi: 10.1103/PhysRevA.58.R34
  • Chu, XZ, M Holzki, R Alheit and G Werth (1998), Observation of high-order motional resonances of an ion cloud in a Paul trap. Int. J. Mass Spectrom. Version: 1 173 (2-Jan) 107-112, issn: 1387-3806, ids: ZC763, doi: 10.1016/S0168-1176(97)00262-0
  • Alheit, R, XZ Chu, M Hoefer, M Holzki, G Werth and R Blumel (1997), Nonlinear collective oscillations of an ion cloud in a Paul trap. Phys. Rev. A Version: 1 56 (5) 4023-4031, issn: 1050-2947, ids: YF529, doi: 10.1103/PhysRevA.56.4023
  • Chu, XZ, SQ Liu and TQ Dong (1996), Experimental study of AC Zeeman effect in Rb-87 atomic frequency standard. Acta Phys. Sin.-Overseas Ed. Version: 1 5 (6) 423-430, issn: 1004-423X, ids: VA201