About the Kapteyn-Murnane Group

Our group is developing new probes of quantum matter using coherent X-ray beams, which have undergone a revolution in the past decade. More than 50 years after the demonstration of the visible laser, it is finally possible to generate laser-like beams spanning the deep-UV, extreme ultraviolet (EUV) and soft X-ray regions of the spectrum by harnessing high harmonic upconversion of femtosecond lasers. Moreover, by combining phase matching techniques and selection rules, we can achieve exquisite “quantum” control over x-ray light. It is now possible to produce short wavelength waveforms with controlled spectral and temporal shapes, polarization state, and phase structure. Exciting recent advances also include the first sub-wavelength imaging at short wavelengths, the ability to directly manipulate spins in materials using light, the first methods to measure the full mechanical properties of ultrathin films and nanostructured media, uncovering new regimes of nanoscale heat flow, as well as routes for mapping new states and phases in quantum materials. Ultrafast coherent EUV and x-ray beams are thus becoming indispensable tools in the race to develop new nanoscale and quantum devices.

We welcome trainees from physics, materials science, engineering and chemistry to work together to solve grand-challenge scientific problems that are also at the technological forefront. Trainees from our group go on to positions in academe, industry and national laboratories.

Research Areas

  • Ever since the invention of the visible laser over 50 years ago, scientists have been striving to create lasers that generate coherent beams at shorter wavelengths i.e. the extreme UV (EUV) and soft X-ray (SXR) regions of the spectrum. This quest has led to the construction of large facilities, such as kilometer-scale x-ray free-electron lasers, to reach the keV photon energy region.

  • Magnetism has been the subject of scientific inquiry for more than 2000 years. However, it is still an incompletely understood phenomenon. The fundamental length and time scales for magnetic phenomena range from Å (exchange lengths) and sub-femtoseconds (exchange splitting) on up. 

  • High harmonics are ideal as the illumination source for time- and angle-resolved photoemission spectroscopy (trARPES), which can measure the full electronic band structure of a material. Moreover, a new generation of ultrafast (~50-100fs), MHz rep rate, VUV (1-20eV) highly-cascaded high harmonics driven by compact fiber lasers have 10-100meV energy resolution, and are ideal for spin-resolved ARPES (Optica 7, 832 (2020).

  • Although x-ray imaging has been explored for decades, and visible-wavelength microscopy for centuries, it is only recently that the spectral region in between―the extreme ultraviolet (EUV)―has been explored for imaging nanostructures and nanomaterials.

  • Heat transport is driven by a thermal gradient, flowing from hot to cold regions in a material. However, at dimensions <100nm, bulk models no longer accurately predict the transport properties of materials. Because no complete models of nanoscale heat transport were available, it was assumed instead that bulk-like diffusive heat transport was valid—provided that an effective parameter, such as a size-dependent thermal conductivity, was incorporated.

  • Nanoparticles exhibit a surface-area-to-volume ratio many orders of magnitude higher than bulk materials, allowing them to serve as powerful catalysts for chemical reactions, both in the laboratory and as atmospheric aerosols.

  • The demand for faster, more efficient, and more compact nanoelectronic devices, like smartphone chips, requires engineers to develop increasingly complex designs. To achieve this, engineers use layer upon layer of very thin films – as thin as only a couple strands of DNA – with impurities added, to tailor the function. 

  • Science and technology are inextricably linked and continue to drive each other. Ultrafast lasers have revolutionized our understanding of how molecules and materials work and how charges, spins, phonons and photons interact dynamically. In past research, our group designed Ti:sapphire lasers that operate at the limits of pulse duration and stability, with adjustable pulse durations from 7 fs on up. 

In the Spotlight

Former JILA postdoctoral researcher Bill Peters
June 01, 2023: Remembering the Former Life of JILAn Bill Peters

Former JILA postdoctoral researcher William “Bill” Peters recently passed away on May 29th after experiencing sudden cardiac arrest while playing soccer with his daughter. Peters was part of JILA Fellows Henry Kapteyn’s and Margaret Murnane’s research group within JILA. Before this position, Peters completed his Ph.D. in physical chemistry at the University of Colorado Boulder in 2013. After completing his postdoc at JILA in 2021, Peters became an optical engineer at Lockheed Martin, working on cutting-edge technological systems. 

His family is holding services this week in Colorado Springs and asks anyone interested in attending to contact Bill’s sister Rebecca Peters, for more information. 

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JILA graduate student Brendan McBennett discusses his work in the laboratories of JILA Fellows Margaret Murnane and Henry Kapteyn
January 13, 2023: Humans of JILA: Brendan McBennett

Surrounded by some of the world’s most advanced lasers, computers, and microscopes sits Brendan McBennett, a graduate student at JILA. McBennett has been working in the laboratories of JILA Fellows Margaret Murnane and Henry Kapteyn, as part of the KM group since 2019, excited to see his research advance significantly over that time. “We use ultraviolet and extreme ultraviolet (EUV) lasers to study heat flow in nanostructured materials,” McBennett states. “EUV photons have a higher photon energy that makes them insensitive to electron dynamics in most materials, combined with nanometer wavelengths. This allows them to very precisely probe surface deformations induced by heat - or thermal phonons – to capture new materials behaviors.” In simple terms, McBennett is looking at heat dissipation in nanoelectronics. “Our experiments are providing a better understanding of phonon thermal transport in nanomaterials to inform the development of new predictive theories,” he says. “The field of phonon transport is still in its infancy, compared to our understanding of electrons and spins. There is a lot of technological potential, for energy efficiency, smarter design of nanoelectronics and quantum devices, and phonon-photon and phonon-electron analogs like phononic crystals and thermal diodes.” McBennett’s previous work at NREL (National Renewable Energy Laboratory) studied the power grid under varying renewable energy and energy efficiency scenarios, and his current research zooms in on this previous focus. 

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McBennett adjusting a wedge, which is an optic that reflects only a small fraction of the laser beam and transmits the rest. This allows imaging of a beam mode on a CMOS (complementary metal oxide semiconductor) camera, which would otherwise be damaged by the full laser power.
December 31, 2022: JILA Graduate Student Brendan McBennett named as 2023 recipient of Nick Cobb Memorial Scholarship

JILA graduate student Brendan McBennett has been announced as the 2023 recipient of the $10,000 Nick Cobb Memorial Scholarship by SPIE, the international society for optics and photonics, and Siemens EDA. McBennett was cited for this award "for his potential contributions to the field related to advanced lithography." At JILA, McBennett works under the supervision of JILA Fellows and University of Colorado Boulder professors Dr. Margaret Murnane and Dr. Henry Kapteyn.

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Postdoctoral researcher Chen-Ting Liao
December 14, 2022: JILA Scientist Chen-Ting Liao is awarded a grant from the 2023 Young Investigator Research Program

JILA scientist Dr. Chen-Ting Liao has been awarded a grant as part of the 2023 Young Investigator Research Program, or YIP. YIP was launched by the Air Force Office of Scientific Research, or AFOSR, the basic research arm of the Air Force Research Laboratory. The AFOSR's mission is to support Air Force goals of control and maximum utilization of air, space, and cyberspace. To do this, AFSOR is awarding $25 million in grants to 58 scientists and engineers from 44 research institutions and businesses in 22 states in 2023. Two grants will be awarded to the quantum information sciences research portfolio for quantum computing funded by the National Security Agency. The remaining awards will be funded by AFOSR YIP and/or core research portfolio funds. YIP recipients receive three-year grants of up to $450,000. 

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JILA Address

We are located at JILA: A joint institute of NIST and the University of Colorado Boulder.

Map | JILA Phone: 303-492-7789 | Address: 440 UCB, Boulder, CO 80309