About

Professor Steven Anlage, Ph.D., from the California Institute of Technology in 1988, is an experimental physicist specializing in the fundamental physics and applications of superconductivity. His research involves investigating the electrodynamic response of superconductors, particularly high-temperature superconductors such as copper-oxide materials, through measurements of microwave surface impedance and fluctuation conductivity. His work aims to elucidate the electron pairing mechanism, measure the intrinsic nonlinear response in the Meissner state, and understand the superconductor/normal phase transition in high-Tc materials. His research encompasses the development and application of near-field microwave microscopes for dielectric and metal measurements at nanometer resolution, as well as the study of quantum chaos through electromagnetic analog experiments. He has contributed to understanding the nonlinear properties of superconductors, the phase transition behavior at finite frequencies, and the development of advanced measurement techniques including scanning laser microscopy of RF current flow. Additionally, Professor Anlage has explored chaos in nonlinear circuits at RF and microwave frequencies, the properties of left-handed metamaterials, and has collaborated with industry to develop commercial near-field microwave microscopes. His work has also extended to innovative wireless power transfer methods and electromagnetic environment resilience, with recognition through awards such as the IEEE Outstanding Young Engineer honor and university invention awards.

Research topics

• Optics
• Computer Science
• Physics
• Mathematics
• Telecommunications
• Particle physics
• Statistics
• Electrical engineering
• Nuclear physics
• Engineering
• Quantum mechanics

Selected publications

• Robust wave splitters based on scattering singularities in complex non-Hermitian systems

  Applied Physics Letters · 2026-02-16

  articleOpen accessSenior author

  We have discovered specific conditions for generic scattering systems to act as wave splitters that are robust to any change in relative amplitude or phase of an arbitrary injected waveform. Specifically for complex systems with tunable parameters, these conditions for robust splitting (RS) are abundant, and by using multiple tunable parameters, the relative amplitude and phase of the output signals can also be tuned. The splitting property of the systems works for all possible input phase differences and amplitude ratios and does not require a particular coherent input signal. We show experimentally that the fixed splitting ratios and output phases at RS conditions are robust to 100 dB of relative power and 2π phase changes of the input waves to a complex non-Hermitian two-port system. We also demonstrate that the splitting power ratio can be tuned by multiple orders of magnitude, and the RS conditions can be tuned to any desired frequency with suitable tunable perturbations embedded in the system. Although this phenomenon is realized in two-port systems and involves some degree of attenuation, tunable robust splitting can be achieved between any two ports of multiport systems. These results are general to all wave scattering phenomena (electromagnetic, acoustic, etc.) and hold in generic complex scattering systems.

  PublisherDOI

• Chirped Pulse Analysis and Control in Non-Hermitian Scattering Systems using Complex Time Delay

  Open MIND · 2026-02-25

  preprint

  We theoretically and experimentally establish a connection between linearly chirped pulse propagation properties and the complex generalization of Wigner-Smith time delay for both transmitted and reflected pulses in linear and dispersive reverberant non-Hermitian scattering systems. We demonstrate that the time shift of the chirped pulse depends on both the real and imaginary parts of the complex time delay of the scattering system. We also show that the chirped pulse experiences a center frequency shift that is directly proportional to the imaginary component of complex time delay, similar to that found in Giovannelli and Anlage (2025). Using these insights, we then demonstrate how complex time delay can be harnessed to systematically tune the propagation properties of a chirped pulse such that a near-zero time shift can be achieved for a wide range of pulse center frequencies in a resonant scattering system. Overall, this work broadens the utility and establishes the physical significance of complex time delays in non-Hermitian settings.

  DOI

• Chirped Pulse Analysis and Control in Non-Hermitian Scattering Systems using Complex Time Delay

  ArXiv.org · 2026-02-25

  articleOpen access

  We theoretically and experimentally establish a connection between linearly chirped pulse propagation properties and the complex generalization of Wigner-Smith time delay for both transmitted and reflected pulses in linear and dispersive reverberant non-Hermitian scattering systems. We demonstrate that the time shift of the chirped pulse depends on both the real and imaginary parts of the complex time delay of the scattering system. We also show that the chirped pulse experiences a center frequency shift that is directly proportional to the imaginary component of complex time delay, similar to that found in Giovannelli and Anlage (2025). Using these insights, we then demonstrate how complex time delay can be harnessed to systematically tune the propagation properties of a chirped pulse such that a near-zero time shift can be achieved for a wide range of pulse center frequencies in a resonant scattering system. Overall, this work broadens the utility and establishes the physical significance of complex time delays in non-Hermitian settings.

  PublisherOA PDF

• Microscopic investigation of rf vortex nucleation in Nb ₃ Sn films using a near-field magnetic microwave microscope

  Superconductor Science and Technology · 2026-02-01

  articleOpen accessSenior author

  Abstract We use a near-field magnetic microwave microscope to investigate and compare rf vortex nucleation in two superconducting radio-frequency-quality Nb 3 Sn films fabricated by different methods: a conventional vapor-diffused film and an electrochemically plated film followed by thermal annealing, both of which are deposited on Nb substrates. The microscope applies a localized rf magnetic field to the sample surface and measures the resulting third-harmonic response <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>P</mml:mi> <mml:mrow> <mml:mn>3</mml:mn> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> , which is particularly sensitive to rf vortex nucleation triggered by surface defects. Both Nb 3 Sn films exhibit nontrivial <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>P</mml:mi> <mml:mrow> <mml:mn>3</mml:mn> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:mi>T</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> structures below 7 K that display the key signatures associated with rf vortex nucleation at local defects. The electrochemical film additionally shows multiple <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>P</mml:mi> <mml:mrow> <mml:mn>3</mml:mn> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:mi>T</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> structures between 14 K and 16 K that are absent in the vapor-diffused sample. Our results highlight the influence of fabrication method on rf vortex penetration properties and demonstrate the utility of third-harmonic response as a local diagnostic tool for surface defects in Nb 3 Sn films.

  PublisherDOI

• Superuniversal statistics with topological origins for non-Hermitian scattering singularities

  Physical Review Research · 2025-11-19 · 1 citations

  articleOpen accessSenior author

  Vortex singularities in speckle patterns formed from random superpositions of waves are an inevitable consequence of destructive interference and are consequently generic and ubiquitous. Singularities are topologically stable, meaning that they persist under small perturbations and can only be removed via pairwise annihilation. They have applications including sensing, imaging, and energy transfer in multiple fields such as optics, acoustics, and elastic or fluid waves. We generalize the concept of singularity speckle patterns to arbitrary two-dimensional parameter spaces and any complex scalar function that describes wave phenomena involving complicated scattering. In scattering systems specifically, we are often concerned with singularities associated with complex zeros of various functions of the scattering matrix <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mi>S</a:mi> </a:math> . Some examples are coherent perfect absorption (CPA), reflectionless scattering modes, transmissionless scattering modes, and <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mi>S</b:mi> </b:math> -matrix exceptional points. Experimentally, we find that all scattering singularities share a universal statistical property: Any quantity that diverges as a simple pole at a singularity, such as <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:mtext>det</c:mtext> <c:mi>S</c:mi> </c:mrow> </c:math> at CPA, has a probability distribution function with a <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:mo>−</d:mo> <d:mn>3</d:mn> </d:mrow> </d:math> power-law tail. The heavy tail of the distribution provides an estimate for the likelihood of finding a given singularity in a generic scattering system. We use these universal statistical results to determine that homogeneous system loss is the most important parameter determining singularity density in a given parameter space of an absorptive scattering system. Finally, we discuss events where distinct singularities coincide in parameter space, which result in higher-order singularities that have applications beyond the capabilities of isolated singularities. These higher-order singularities are not topologically protected, and we do not find universal statistical properties for them. We support our empirical results from microwave experiments with random matrix theory simulations and conclude that the statistical results presented hold for all generic non-Hermitian scattering systems in which singularities can occur.

  PublisherDOI

• Microwave microscope studies of trapped vortex dynamics in superconductors

  Physical review. B./Physical review. B · 2025-06-09 · 4 citations

  articleOpen accessSenior author

  Trapped vortices in superconductors introduce residual resistance in superconducting radio-frequency (SRF) cavities and disrupt the operation of superconducting quantum and digital electronic circuits. Understanding the detailed dynamics of trapped vortices under oscillating magnetic fields is essential for advancing these technologies. We have developed a near-field magnetic microwave microscope to study the dynamics of a limited number of trapped vortices under the probe when stimulated by a localized rf magnetic field. By measuring the local second-harmonic response ($P_\mathrm{2f}$) at sub-femto-Watt levels, we isolate signals exclusively arising from trapped vortices, excluding contributions from surface defects and Meissner screening currents. Toy models of Niobium superconductor hosting vortex pinning sites are introduced and studied with Time-Dependent Ginzburg-Landau (TDGL) simulations of probe/sample interaction to better understand the measured second-harmonic response. The simulation results demonstrate that the second-harmonic response of trapped vortex motion under a localized rf magnetic field shares key features with the experimental data. This measurement technique provides access to vortex dynamics at the micron scale, such as depinning events and spatially-resolved pinning properties, as demonstrated in measurements on a Niobium film with an antidot flux pinning array.

  PublisherOA PDFDOI

• Topology and manipulation of scattering singularities in complex non-Hermitian systems: Two-channel case

  Physical Review Research · 2025-04-25 · 11 citations

  articleOpen accessSenior author

  The control of wave scattering in complex non-Hermitian settings is an exciting subject—often challenging the creativity of researchers and stimulating the imagination of the public. Successful outcomes include invisibility cloaks, wavefront shaping protocols, active metasurface development, and more. At their core, these achievements rely on our ability to engineer the resonant spectrum of the underlying physical structures, which is conventionally accomplished by carefully imposing geometrical and/or dynamical symmetries. In contrast, by taking active control over the boundary conditions in complex scattering environments that lack artificially imposed geometric symmetries, we demonstrate via microwave experiments the ability to manipulate the spectrum of the scattering operator. This active control empowers the creation, destruction, and repositioning of exceptional point degeneracies (EPDs) in a two-dimensional parameter space. The presence of EPDs signifies a coalescence of the scattering eigenmodes, which dramatically affects transport. The scattering EPDs are partitioned in domains characterized by a binary charge, as well as an integer winding number, they are topologically stable in the two-dimensional parameter space, and they obey winding number-conservation laws upon interactions with each other, even in cases in which Lorentz reciprocity is violated; in this case, the topological domains are destroyed. The ramifications of this understanding are the proposition for a unique input-magnitude and phase-insensitive 50:50 in-phase/quadrature (I/Q) power splitter. Our study establishes an important step towards complete control of scattering processes in complex non-Hermitian settings.

  PublisherOA PDFDOI

• Superuniversal Statistics of Complex Time Delays in Non-Hermitian Scattering Systems

  Physical Review Letters · 2025-04-11 · 5 citations

  articleOpen accessSenior author

  The Wigner-Smith time delay of flux conserving systems is a real quantity that measures how long an excitation resides in an interaction region. The complex generalization of time delay to non-Hermitian systems is still under development, in particular, its statistical properties in the short-wavelength limit of complex chaotic scattering systems has not been investigated. From the experimentally measured multiport scattering (S) matrices of one-dimensional graphs, a two-dimensional billiard, and a three-dimensional cavity, we calculate the complex Wigner-Smith (τ_{WS}), as well as each individual reflection (τ_{xx}) and transmission (τ_{xy}) time delay. The complex reflection time-delay differences (τ_{δR}) between each port are calculated, and the transmission time-delay differences (τ_{δT}) are introduced for systems exhibiting nonreciprocal scattering. Large time delays are associated with scattering singularities such as coherent perfect absorption, reflectionless scattering, slow light, and unidirectional invisibility. We demonstrate that the large-delay tails of the distributions of the real and imaginary parts of each time-delay quantity are superuniversal, independent of experimental parameters: wave propagation dimension D, number of scattering channels M, Dyson symmetry class β, and uniform attenuation η. The tails determine the abundance of the singularities in generic scattering systems, and the superuniversality is in direct contrast with the well-established time-delay statistics of unitary scattering systems, where the tail of the τ_{WS} distribution depends explicitly on the values of M and β. We relate the distribution statistics to the topological properties of the corresponding singularities. Although the results presented here are based on classical microwave experiments, they are applicable to any non-Hermitian wave-chaotic scattering system in the short-wavelength limit, such as optical or acoustic resonators.

  PublisherOA PDFDOI

• Revealing isotropic abundant low-energy excitations in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>UTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> through complex microwave surface impedance

  Physical review. B./Physical review. B · 2025-06-25 · 1 citations

  articleOpen accessSenior author

  The complex surface impedance is a well-established tool to study the super- and normal-fluid responses of superconductors. Fundamental properties of the superconductor, such as the pairing mechanism, Fermi surface, and topological properties, also influence the surface impedance. We explore the microwave surface impedance of spin-triplet <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>UTe</a:mi><a:mn>2</a:mn></a:msub></a:math> single crystals as a function of temperature using resonant cavity perturbation measurements employing a multimodal analysis to gain insight into these properties. We determine a composite surface impedance of the crystal for each mode using resonance data combined with the independently measured normal state dc resistivity tensor. The normal state surface impedance reveals the weighting of current flow directions in the crystal of each resonant mode. For <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>UTe</b:mi><b:mn>2</b:mn></b:msub></b:math>, we find an isotropic <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mrow><c:mi mathvariant="normal">Δ</c:mi><c:mi>λ</c:mi><c:mrow><c:mo>(</c:mo><c:mi>T</c:mi><c:mo>)</c:mo></c:mrow><c:mo>∼</c:mo><c:msup><c:mi>T</c:mi><c:mi>α</c:mi></c:msup></c:mrow></c:math> power-law temperature dependence for the magnetic penetration depth for <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:mrow><e:mi>T</e:mi><e:mo>≤</e:mo><e:msub><e:mi>T</e:mi><e:mi>c</e:mi></e:msub><e:mo>/</e:mo><e:mn>3</e:mn></e:mrow></e:math> with <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:mrow><f:mi>α</f:mi><f:mo>&lt;</f:mo><f:mn>2</f:mn></f:mrow></f:math>, which is inconsistent with a single pair of point nodes on the Fermi surface under weak scattering. We also find a similar power-law temperature dependence for the low-temperature surface resistance <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:mrow><g:msub><g:mi>R</g:mi><g:mi>s</g:mi></g:msub><g:mrow><g:mo>(</g:mo><g:mi>T</g:mi><g:mo>)</g:mo></g:mrow><g:mo>∼</g:mo><g:msup><g:mi>T</g:mi><g:msub><g:mi>α</g:mi><g:mi>R</g:mi></g:msub></g:msup></g:mrow></g:math> with <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mrow><h:msub><h:mi>α</h:mi><h:mi>R</h:mi></h:msub><h:mo>&lt;</h:mo><h:mn>2</h:mn></h:mrow></h:math>. We observe a strong anisotropy of the residual microwave loss across these modes, with some modes showing loss below the universal line-nodal value, to those showing substantially more. We compare to predictions for topological Weyl superconductivity in the context of the observed isotropic power laws and anisotropy of the residual loss.

  PublisherDOI

• Discovery of new scattering singularities in complex non-Hermitean systems

  2025-06-16

  article1st authorCorresponding

  The control of wave scattering in complex non-Hermitian settings is an exciting subject – often challenging the creativity of researchers and stimulating the imagination of the public. Successful outcomes include invisibility cloaks, wavefront shaping protocols, active metasurface development, and more. At their core, these achievements rely on our ability to engineer the resonant spectrum of the underlying physical structures which is conventionally accomplished by carefully imposing geometrical and/or dynamical symmetries. In contrast, by taking active control over the boundary conditions in complex scattering environments which lack artificially-imposed geometric symmetries, we demonstrate via microwave experiments the ability to manipulate the spectrum of the scattering operator [1]. This active control empowers the creation, destruction and repositioning of exceptional point degeneracies (EPD’s) in a twodimensional (2D) parameter space [2]. The presence of EPD’s signifies a coalescence of the scattering eigenmodes, which dramatically affects transport. The scattering EPD’s are partitioned in domains characterized by a binary charge, as well as an integer winding number, are topologically stable in the two-dimensional parameter space, and obey winding number-conservation laws upon interactions with each other, even in cases where Lorentz reciprocity is violated; in this case the topological domains are destroyed. Ramifications of this understanding is the proposition for a unique input-magnitude and phase-insensitive 50:50 in-phase/quadrature (I/Q) power splitter. Our study establishes an important step towards complete control of scattering processes in complex non-Hermitian settings.

  PublisherDOI

Recent grants

• Superconducting Metamaterials

  NSF · $270k · 2003–2007

• A Novel Gap Spectroscopy Tool and Discovery of New Nodal Superconductors

  NSF · $359k · 2014–2018

• RINGS: Harnessing the Complexity of Modern Electromagnetic Environments for Resilient Wireless Communications

  NSF · $1.0M · 2022–2026

• Novel Superconducting Physics Through Microwave Imaging

  NSF · $650k · 2020–2024

• GOALI: Dynamically Tunable Low-Loss Active Metamaterials For Wireless Applications

  NSF · $501k · 2012–2015

Frequent coauthors

• Nicola Pompeo

  Roma Tre University

  961 shared

• Thomas Siegert

  University of West Florida

  961 shared

• F Gömöry

  961 shared

• Sergio Benedetto

  Xi'an Jiaotong University

  961 shared

• Gregory W. Lyons

  DEVCOM Army Research Laboratory

  961 shared

• Naoyuki Amemiya

  Kyoto University

  961 shared

• T. Kiss

  961 shared

• Susana Izquierdo Bermúdez

  European Organization for Nuclear Research

  961 shared

Awards & honors

• Glenn L. Martin Medal
• Greenaugh Award
• Innovation Hall of Fame
• 125th Anniversary Medal
• Early Career Distinguished Alumni Society