I am an observational cosmologist, and an experimental physicist. I build ultra-low-noise detectors using superconducting and quantum sensing techniques, and use them in experiments and instrumentation for cosmology. I currently spend most of my time investigating the inflation paradigm of standard cosmology, using the cosmic microwave background (CMB). Recently, I've become interested in using the weak lensing of the CMB in conjunction with galaxy surveys to study the growth of large-scale structure in the universe.

I received my PhD in particle astrophysics from Caltech in 2012, working on direct detection of WIMP dark matter with the CDMS-II experiment. I then shifted my effort to searching for inflation with the CMB. I was a postdoctoral scholar at Stanford through 2015 before being appointed as a Wolfgang Panofsky Fellow at SLAC National Accelerator Laboratory. In 2017, I won a DOE Office of Science Early Career Award to work on new signal transduction and superconducting multiplexing techniques for next-generation CMB cameras. In 2020, I was appointed as a Lead Scientist at SLAC, and in 2023, I was appointed Associate Professor of Particle Physics and Astrophysics at Stanford and SLAC. I serve as CMB department head in the Fundamental Physics Directorate at SLAC. I also serve as scientific project manager for the bring up of SLAC's Detector Microfabrication Facility for the development of superconducting and quantum sensors and devices.

Academic Appointments

  • Associate Professor, Particle Physics and Astrophysics

2023-24 Courses

All Publications

  • SLAC microresonator RF (SMuRF) electronics: A tone-tracking readout system for superconducting microwave resonator arrays. The Review of scientific instruments Yu, C., Ahmed, Z., Frisch, J. C., Henderson, S. W., Silva-Feaver, M., Arnold, K., Brown, D., Connors, J., Cukierman, A. J., D'Ewart, J. M., Dober, B. J., Dusatko, J. E., Haller, G., Herbst, R., Hilton, G. C., Hubmayr, J., Irwin, K. D., Kuo, C., Mates, J. A., Ruckman, L., Ullom, J., Vale, L., Van Winkle, D. D., Vasquez, J., Young, E. 2023; 94 (1): 014712


    We describe the newest generation of the SLAC Microresonator RF (SMuRF) electronics, a warm digital control and readout system for microwave-frequency resonator-based cryogenic detector and multiplexer systems, such as microwave superconducting quantum interference device multiplexers (mumux) or microwave kinetic inductance detectors. Ultra-sensitive measurements in particle physics and astronomy increasingly rely on large arrays of cryogenic sensors, which in turn necessitate highly multiplexed readout and accompanying room-temperature electronics. Microwave-frequency resonators are a popular tool for cryogenic multiplexing, with the potential to multiplex thousands of detector channels on one readout line. The SMuRF system provides the capability for reading out up to 3328 channels across a 4-8GHz bandwidth. Notably, the SMuRF system is unique in its implementation of a closed-loop tone-tracking algorithm that minimizes RF power transmitted to the cold amplifier, substantially relaxing system linearity requirements and effective noise from intermodulation products. Here, we present a description of the hardware, firmware, and software systems of the SMuRF electronics, comparing achieved performance with science-driven design requirements. In particular, we focus on the case of large-channel-count, low-bandwidth applications, but the system has been easily reconfigured for high-bandwidth applications. The system described here has been successfully deployed in lab settings and field sites around the world and is baselined for use on upcoming large-scale observatories.

    View details for DOI 10.1063/5.0125084

    View details for PubMedID 36725567

  • CMB-S4: Forecasting Constraints on Primordial Gravitational Waves ASTROPHYSICAL JOURNAL Abazajian, K., Addison, G. E., Adshead, P., Ahmed, Z., Akerib, D., Ali, A., Allen, S. W., Alonso, D., Alvarez, M., Amin, M. A., Anderson, A., Arnold, K. S., Ashton, P., Baccigalupi, C., Bard, D., Barkats, D., Barron, D., Barry, P. S., Bartlett, J. G., Thakur, R., Battaglia, N., Bean, R., Bebek, C., Bender, A. N., Benson, B. A., Bianchini, F., Bischoff, C. A., Bleem, L., Bock, J. J., Bocquet, S., Boddy, K. K., Bond, J., Borrill, J., Bouchet, F. R., Brinckmann, T., Brown, M. L., Bryan, S., Buza, V., Byrum, K., Caimapo, C., Calabrese, E., Calafut, V., Caldwell, R., Carlstrom, J. E., Carron, J., Cecil, T., Challinor, A., Chang, C. L., Chinone, Y., Cho, H., Cooray, A., Coulton, W., Crawford, T. M., Crites, A., Cukierman, A., Cyr-Racine, F., de Haan, T., Delabrouille, J., Devlin, M., Di Valentino, E., Dierickx, M., Dobbs, M., Duff, S., Dvorkin, C., Eimer, J., Elleflot, T., Errard, J., Essinger-Hileman, T., Fabbian, G., Feng, C., Ferraro, S., Filippini, J. P., Flauger, R., Flaugher, B., Fraisse, A. A., Frolov, A., Galitzki, N., Gallardo, P. A., Galli, S., Ganga, K., Gerbino, M., Gluscevic, V., Goeckner-Wald, N., Green, D., Grin, D., Grohs, E., Gualtieri, R., Gudmundsson, J. E., Gullett, I., Gupta, N., Habib, S., Halpern, M., Halverson, N. W., Hanany, S., Harrington, K., Hasegawa, M., Hasselfield, M., Hazumi, M., Heitmann, K., Henderson, S., Hensley, B., Hill, C., Hill, J., Hlozek, R., Ho, S., Hoang, T., Holder, G., Holzapfel, W., Hood, J., Hubmayr, J., Huffenberger, K. M., Hui, H., Irwin, K., Jeong, O., Johnson, B. R., Jones, W. C., Kang, J., Karkare, K. S., Katayama, N., Keskitalo, R., Kisner, T., Knox, L., Koopman, B. J., Kosowsky, A., Kovac, J., Kovetz, E. D., Kuhlmann, S., Kuo, C., Kusaka, A., Lahteenmaki, A., Lawrence, C. R., Lee, A. T., Lewis, A., Li, D., Linder, E., Loverde, M., Lowitz, A., Lubin, P., Madhavacheril, M. S., Mantz, A., Marques, G., Matsuda, F., Mauskopf, P., McCarrick, H., McMahon, J., Meerburg, P., Melin, J., Menanteau, F., Meyers, J., Millea, M., Mohr, J., Moncelsi, L., Monzani, M., Mroczkowski, T., Mukherjee, S., Nagy, J., Namikawa, T., Nati, F., Natoli, T., Newburgh, L., Niemack, M. D., Nishino, H., Nord, B., Novosad, V., O'Brient, R., Padin, S., Palladino, S., Partridge, B., Petravick, D., Pierpaoli, E., Pogosian, L., Prabhu, K., Pryke, C., Puglisi, G., Racine, B., Rahlin, A., Rao, M., Raveri, M., Reichardt, C. L., Remazeilles, M., Rocha, G., Roe, N. A., Roy, A., Ruhl, J. E., Salatino, M., Saliwanchik, B., Schaan, E., Schillaci, A., Schmitt, B., Schmittfull, M. M., Scott, D., Sehgal, N., Shandera, S., Sherwin, B. D., Shirokoff, E., Simon, S. M., Slosar, A., Spergel, D., St Germaine, T., Staggs, S. T., Stark, A., Starkman, G. D., Stompor, R., Stoughton, C., Suzuki, A., Tajima, O., Teply, G. P., Thompson, K., Thorne, B., Timbie, P., Tomasi, M., Tristram, M., Tucker, G., Umilta, C., van Engelen, A., Vavagiakis, E. M., Vieira, J. D., Vieregg, A. G., Wagoner, K., Wallisch, B., Wang, G., Watson, S., Westbrook, B., Whitehorn, N., Wollack, E. J., Wu, W., Xu, Z., Yang, H., Yasini, S., Yefremenko, V. G., Yoon, K., Young, E., Yu, C., Zonca, A., CMB-S4 Collaboration 2022; 926 (1)
  • Advanced RFSoC readout for space-based superconducting sensor arrays Henderson, S. W., Ahmed, Z., D'Ewart, J. M., Frisch, J. C., Herbst, R., Liu, C., Ma, L., Ruckman, L., Van Winkle, D. D., Yu, C., Zmuidzinas, J., Gao SPIE-INT SOC OPTICAL ENGINEERING. 2022

    View details for DOI 10.1117/12.2630412

    View details for Web of Science ID 000864182000022

  • A simulation suite for readout with SMuRF tone-tracking electronics Yu, C., Ahmed, Z., D'Ewart, J. M., Frisch, J. C., Henderson, S. W., Silva-Feaver, M., Zmuidzinas, J., Gao SPIE-INT SOC OPTICAL ENGINEERING. 2022

    View details for DOI 10.1117/12.2629718

    View details for Web of Science ID 000864182000030

  • Phase Drift Monitoring for Tone Tracking Readout of Superconducting Microwave Resonators Silva-Feaver, M., Ahmed, Z., Arnold, K. S., Frisch, J. C., Groh, J., Henderson, S. W., Vasquez, J., Yu, C., Zmuidzinas, J., Gao SPIE-INT SOC OPTICAL ENGINEERING. 2022

    View details for DOI 10.1117/12.2629024

    View details for Web of Science ID 000864182000029

  • The Simons Observatory Microwave SQUID Multiplexing Detector Module Design ASTROPHYSICAL JOURNAL McCarrick, H., Healy, E., Ahmed, Z., Arnold, K., Atkins, Z., Austermann, J. E., Bhandarkar, T., Beall, J. A., Bruno, S., Choi, S. K., Connors, J., Cothard, N. F., Crowley, K. D., Dicker, S., Dober, B., Duell, C. J., Duff, S. M., Dutcher, D., Frisch, J. C., Galitzki, N., Gralla, M. B., Gudmundsson, J. E., Henderson, S. W., Hilton, G. C., Ho, S., Huber, Z. B., Hubmayr, J., Iuliano, J., Johnson, B. R., Kofman, A. M., Kusaka, A., Lashner, J., Lee, A. T., Li, Y., Link, M. J., Lucas, T. J., Lungu, M., Mates, J. B., McMahon, J. J., Niemack, M. D., Orlowski-Scherer, J., Seibert, J., Silva-Feaver, M., Simon, S. M., Staggs, S., Suzuki, A., Terasaki, T., Ullom, J. N., Vavagiakis, E. M., Vale, L. R., Van Lanen, J., Vissers, M. R., Wang, Y., Wollack, E. J., Xu, Z., Young, E., Yu, C., Zheng, K., Zhu, N., Thornton, R. 2021; 922 (1)
  • The Simons Observatory: science goals and forecasts JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS Ade, P., Aguirre, J., Ahmed, Z., Aiola, S., Ali, A., Alonso, D., Alvarez, M. A., Arnold, K., Ashton, P., Austermann, J., Awan, H., Baccigalupi, C., Baildon, T., Barron, D., Battaglia, N., Battye, R., Baxter, E., Bazarko, A., Beall, J. A., Bean, R., Beck, D., Beckman, S., Beringue, B., Bianchini, F., Boada, S., Boettger, D., Bond, J., Borrill, J., Brown, M. L., Bruno, S., Bryan, S., Calabrese, E., Calafut, V., Calisse, P., Carron, J., Challinor, A., Chesmore, G., Chinone, Y., Chluba, J., Cho, H., Choi, S., Coppi, G., Cothard, N. F., Coughlin, K., Crichton, D., Crowley, K. D., Crowley, K. T., Cukierman, A., D'Ewart, J. M., Dunner, R., de Haan, T., Devlin, M., Dicker, S., Didier, J., Dobbs, M., Dober, B., Duell, C. J., Duff, S., Duivenvoorden, A., Dunkley, J., Dusatko, J., Errard, J., Fabbian, G., Feeney, S., Ferraro, S., Fluxa, P., Freese, K., Frisch, J. C., Frolov, A., Fuller, G., Fuzia, B., Galitzki, N., Gallardo, P. A., Ghersi, J., Gao, J., Gawiser, E., Gerbino, M., Gluscevic, V., Goeckner-Wald, N., Golec, J., Gordon, S., Gralla, M., Green, D., Grigorian, A., Groh, J., Groppi, C., Guan, Y., Gudmundsson, J. E., Han, D., Hargrave, P., Hasegawa, M., Hasselfield, M., Hattori, M., Haynes, V., Hazumi, M., He, Y., Healy, E., Henderson, S. W., Hervias-Caimapo, C., Hill, C. A., Hill, J., Hilton, G., Hilton, M., Hincks, A. D., Hinshaw, G., Hlozek, R., Ho, S., Ho, S., Howe, L., Huang, Z., Hubmayr, J., Huffenberger, K., Hughes, J. P., Ijjas, A., Ikape, M., Irwin, K., Jaffe, A. H., Jain, B., Jeong, O., Kaneko, D., Karpel, E. D., Katayama, N., Keating, B., Kernasovskiy, S. S., Keskitalo, R., Kisner, T., Kiuchi, K., Klein, J., Knowles, K., Koopman, B., Kosowsky, A., Krachmalnicoff, N., Kuenstner, S. E., Kuo, C., Kusaka, A., Lashner, J., Lee, A., Lee, E., Leon, D., Leung, J., Lewis, A., Li, Y., Li, Z., Limon, M., Linder, E., Lopez-Caraballo, C., Louis, T., Lowry, L., Lungu, M., Madhavacheril, M., Mak, D., Maldonado, F., Mani, H., Mates, B., Matsuda, F., Maurin, L., Mauskopf, P., May, A., McCallum, N., McKenney, C., McMahon, J., Meerburg, P., Meyers, J., Miller, A., Mirmelstein, M., Moodley, K., Munchmeyer, M., Munson, C., Naess, S., Nati, F., Navaroli, M., Newburgh, L., Ho Nam Nguyen, Niemack, M., Nishino, H., Orlowski-Scherer, J., Page, L., Partridge, B., Peloton, J., Perrotta, F., Piccirillo, L., Pisano, G., Poletti, D., Puddu, R., Puglisi, G., Raum, C., Reichardt, C. L., Remazeilles, M., Rephaeli, Y., Riechers, D., Rojas, F., Roy, A., Sadeh, S., Sakurail, Y., Salatino, M., Rao, M., Schaan, E., Schmittfull, M., Sehgal, N., Seibert, J., Seljak, U., Sherwin, B., Shimon, M., Sierra, C., Sievers, J., Sikhosana, P., Silva-Feaver, M., Simon, S. M., Sinclair, A., Siritanasak, P., Smith, K., Smith, S. R., Spergel, D., Staggs, S. T., Stein, G., Stevens, J. R., Stompor, R., Suzuki, A., Tajima, O., Takakura, S., Teply, G., Thomas, D. B., Thorne, B., Thornton, R., Trac, H., Tsai, C., Tucker, C., Ullom, J., Vagnozzi, S., van Engelen, A., Van Lanen, J., Van Winkle, D. D., Vavagiakis, E. M., Verges, C., Vissers, M., Wagoner, K., Walker, S., Ward, J., Westbrook, B., Whitehorn, N., Williams, J., Williams, J., Wollack, E. J., Xu, Z., Yu, B., Yu, C., Zago, F., Zhang, H., Zhu, N., Simons Observ Collaboration 2019
  • Next-generation small CMB telescopes Thompson, K. L., Kuo, C., Yoon, K., Ahmed, Z., Marshall, H. K., Spyromilio, J. SPIE-INT SOC OPTICAL ENGINEERING. 2018

    View details for DOI 10.1117/12.2313927

    View details for Web of Science ID 000450858000126

  • Highly-multiplexed microwave SQUID readout using the SLAC Microresonator Radio Frequency (SMuRF) Electronics for Future CMB and Sub-millimeter Surveys Henderson, S. W., Ahmed, Z., Austermann, J., Becker, D., Bennett, D. A., Brown, D., Chaudhuri, S., Cho, H., D'Ewart, J. M., Dober, B., Duff, S. M., Dusatko, J. E., Fatigoni, S., Frisch, J. C., Gard, J. D., Halpern, M., Hilton, G. C., Hubmayr, J., Irwin, K. D., Karpel, E. D., Kernasovskiy, S. S., Kuenstner, S. E., Kuo, C., Li, D., Mates, J. B., Reintsema, C. D., Smith, S. R., Ullom, J., Vale, L. R., Van Winkle, D. D., Vissers, M., Yu, C., Zmuidzinas, J., Gao SPIE-INT SOC OPTICAL ENGINEERING. 2018

    View details for DOI 10.1117/12.2314435

    View details for Web of Science ID 000451719300023