Many anticipated discoveries in fundamental science demand better measurement sensitivity. For acoustic sensors, mechanical dissipation sets this limit via the fluctuation-dissipation theorem. Yet, even in high-purity crystals, its microscopic origin remains poorly understood, and external enhancement, such as tension-induced dissipation dilution, is difficult to realize. Here, we realize a strain-engineered diamond nanomechanical platform using van der Waals self-assembly that harnesses surface forces to apply tensile stress exceeding 1 GPa. At cryogenic temperatures, these resonators achieve quality factors beyond 10^10. This exceptional coherence allows us to resolve residual dissipation channels, elucidating distinct two-level systems and topological dissipation from a surface superfluid helium film. Advancing mechanical coherence therefore opens access to new regimes of physics in hybrid quantum systems, precision metrology, and condensed-matter physics.

Neutral-atom arrays have emerged as a leading platform for scalable quantum computing, combining excellent coherence, optical control of large qubit ensembles, and flexible all-to-all connectivity. Achieving fault tolerance, however, requires efficient error detection and correction. Ytterbium offers unique advantages through its metastable-state qubits: leakage to the ground state can be independently detected, converting physical errors into erasures with known locations, while single-photon excitation to Rydberg states enables scalable, high-fidelity two qubit gates. We report progress toward improving two-qubit entangling gate fidelities in a 171Yb array. The gate is primarily limited by the finite Rydberg lifetime; recent upgrades to our ultraviolet excitation system enable higher Rabi frequencies that mitigate this effect. We develop new experimental optimization techniques, and compare our results with simulations to better understand the current limitations. These advances mark a key step toward scalable, fault-tolerant quantum computing with neutral atoms.

Building new tools capable of studying phenomena beyond the reach of current technologies opens exciting opportunities. Quantum sensors harness the small and fragile nature of the qubits to achieve extremely precise measurements, enabling breakthroughs in fundamental physics and real-world applications by pushing resolution and sensitivity to new limits.

In this talk, I’ll discuss two approaches to quantum-enhanced sensing. The first is developing a novel quantum sensor that can be placed closer to the target of interest. We introduce a surface molecular qubit formed by pentacene molecules scaffolded on a two-dimensional (2D) material, hexagonal boron nitride (hBN). This qubit exhibits stable fluorescence and optically detected magnetic resonance (ODMR) from cryogenic to ambient conditions. With fully deuterated pentacene, the Hahn-echo coherence time reaches 22 µs and extends to 214 µs under dynamical decoupling, outperforming state-of-the-art shallow NV centers in diamond despite being positioned directly on the surface.

The second approach leverages entanglement. I will introduce a variational method for generating metrological states in small dipolar-interacting spin ensembles with limited qubit control. Simulations show that, for both regular and disordered spatial configurations, the generated states enable sensing beyond the standard quantum limit (SQL) and, for small spin numbers, approach the Heisenberg limit (HL). The resulting states resemble Greenberger–Horne–Zeilinger (GHZ) states or spin-squeezed states (SSS). This advantage persists in the presence of finite spin initialization fidelity and a non-Markovian noise environment.

Emergent quantum phases often arise when interactions extend beyond nearest neighbors, giving rise to frustration, topology, and competing orders. Dipolar quantum gases offer a uniquely tunable and microscopically controlled platform for engineering and probing such long-range quantum matter. In this talk, I present two complementary experimental platforms that advance this frontier.
First, we realize a dipolar quantum gas microscope using magnetic atoms in a small-spacing optical lattice, where coherent tunneling competes directly with tunable dipole–dipole interactions. An accordion-lattice expansion enables rapid, high-fidelity site-resolved imaging. With this platform, we observe dipolar quantum solids exhibiting checkerboard and stripe order and identify interaction driven topological transitions through measurements of nonlocal string order.
I then turn to ultracold ground-state NaCs molecules, where long-lived molecular Bose–Einstein condensates reach strongly interacting dipolar regimes previously limited by inelastic loss. Microwave dressing tunes interaction strength and anisotropy, producing droplet arrays and related interaction-driven structures. These advances set the stage for unconventional Hubbard and spin models with engineered long-range couplings in optical lattices.

People interested in talking to Lin can sign up in the following sheet: https://docs.google.com/spreadsheets/d/1AXyUejuPDE5Woer-r1EDhwmSXxeeOA3vp90T4SXVwXw/edit?usp=sharing

Continuous-variable quantum systems enable encoding complex states in fewer modes through large-scale non-Gaussian states. Motion, as a continuous degree of freedom, underlies phenomena from Cooper pair dynamics to levitated macroscopic objects. Hence, realizing high-energy, spatially extended motional states remains key for advancing quantum sensing, simulation, and foundational tests.
In the talk, I will present the following control tasks for various nonlinear mechanical systems, including trapped atoms, levitated particles, and clamped oscillators with spin-motion coupling.
(i) Nonharmonic potential modulation: Optimal control of a particle in a nonharmonic potential enables the generation of non-Gaussian states and arbitrary unitaries within a chosen two-level subspace.
(ii) Macroscopic quantum states of levitated particles: Rapid preparation of a particle’s center of mass in a macroscopic superposition is achieved by releasing it from a harmonic trap into a static double-well potential after ground-state cooling.
(iii) Phase-insensitive displacement sensing: For randomized phase-space displacements, quantum optimal control identifies number-squeezed cat states as optimal for force sensitivity under lossy dynamics.
These approaches exploit either intrinsic nonharmonicity or coherent nonlinear coupling, providing a unified framework for motion control in continuous-variable quantum systems—from levitated nanoparticles to optical and microwave resonators—paving the way toward universal quantum control of mechanical degrees of freedom.

The interplay between spin and charge in chiral materials — ranging from simple organic molecules to complex hybrid semiconductors — has emerged as one of the more intriguing open scientific problems. Chirality is fundamentally a symmetry question — an object is chiral if it cannot be superimposed on its mirror image — and chirality-induced spin selectivity (CISS), whereby chiral materials preferentially transmit electrons of a particular spin orientation, is a striking consequence of this broken symmetry. This observation has proven controversial, as large spin polarization from organic molecules challenges conventional wisdom about the requirements for spin-selective transport. The underlying symmetry constraint is elegant: reversing the structural handedness or the electron spin independently produces measurably different outcomes, while reversing both simultaneously leaves observables unchanged. Yet translating these symmetry constraints into a complete microscopic theory has remained challenging despite two decades of robust experimental evidence. We have developed a new class of chiral organic-inorganic hybrid semiconductors in which chiral molecules imbue chirality into an inorganic semiconductor framework. Using this platform, I will present experimental demonstrations of both CISS and Inverse-CISS and show how the observed symmetry behavior places meaningful constraints on theory. These constraints point toward a natural resolution in which spin and spatial degrees of freedom in chiral materials are fundamentally non-separable, giving rise to spin-displacement order with no analog in achiral systems.

Competition among multiple orders is a defining feature of strongly correlated matter, from frustrated magnets to high-T_c superconductors. Here, I will present two examples where quantum dynamics is governed by such multiparty competition.
In the first part, we briefly discuss the dynamics of a Kondo impurity coupled to an attractive Fermi–Hubbard bath. Examining transport between two one-dimensional leads connected by the impurity, we find long-time competition among charge, magnetic, and superconducting orders: a dynamical crossover from superconducting to charge-density-wave order precedes a DC current peak driven by Kondo correlations.
In the second part, we study one-dimensional fermions evolving under a BCS Hamiltonian with gap Δ, subject to on-site, spin-selective number measurements at rate p. Defying the common expectation that LOCC measurements cannot increase steady-state entanglement, we show that for Δ>0 the steady-state entropy S_s grows with p over a finite interval 0<p<p_th. The mechanism is a multiparty competition among unitary entanglement generation, measurement, and fermion pairing: pairing suppresses entanglement, measurement suppresses pairing, and together these effects yield a net increase in entanglement S_s as the measurement rate p rises.
Taken together, these results showcase the rich nonequilibrium phenomena that arise from multiparty competition under both unitary and monitored dynamics.
 

Quantum transducers provide a pathway to link superconducting circuits to quantum networks that extend over large distances at ambient temperatures. Here, we present our progress toward entangling a superconducting qubit in a dilution refrigerator with a time-bin encoded optical qubit propagating through a room temperature telecom fiber. Starting from a transmon qubit coupled to a microwave resonator, we generate an itinerant time-bin encoded microwave qubit entangled with the transmon. We then route the microwave photon to an electro-optic transducer that upconverts it to the optical domain. To verify the entanglement fidelity, we perform simultaneous measurements of the superconducting qubit and the optical qubit states, and we show evidence of correlations in both longitudinal and transversal bases.

In this talk, I will discuss two recent developments centered on the physics and manipulation of hyperfine interactions in atomic and molecular systems. First, I will introduce an all-optical method for performing qudit gate operations in alkaline-earth and alkaline-earth-like atoms. Our scheme utilizes single-beam Raman transitions within the 1S0 to 3P1 manifold to achieve coherent manipulation of high-dimensional hyperfine levels, compatible with non-destructive readout and two-qudit gates via Rydberg blockade.

Second, I will shift to the molecular domain to explore the coupling between magnetism and atomic or molecular motion. This topic has seen a recent surge of interest due to the study of chiral phonons in solid state systems. Using modern ab initio methods and analytic models, we conduct a theoretically rigorous investigation of vibrational molecular magnetism, re-visiting this long-standing problem to derive relevant coupling parameters for spin-vibration interactions and predict localized, vibrationally induced magnetic fields.

Wildfires are becoming increasingly frequent and intense in a warming climate, reversing decades of air quality improvements, as seen in the 2025 Los Angeles Fires and many other record-breaking events worldwide. Crucially, what burns locally doesn’t stay local—wildfire smoke often rises, travels, and affects the atmosphere and climate far beyond its source. I will share new insights into the far-reaching impacts of wildfire smoke based on aircraft measurements, satellite observations, and modeling. At the regional scale, I will present first-of-its-kind aircraft sampling of wildfire smoke at ~14.5 km altitude, revealing unexpectedly large aerosol particles that enhance outgoing radiation by ~35%, challenging conventional model assumptions. Next, I will show how high-altitude wildfire smoke perturbs Earth’s energy balance and global temperatures, with the 2019/20 Australian wildfires leaving detectable climate fingerprints in the atmosphere comparable to major volcanic eruptions, and causing the strongest stratospheric warming of this century. I will conclude with future perspectives on bridging measurements and modeling to advance understanding of aerosol-chemistry-climate interactions in a world increasingly shaped by wildfires and shifting anthropogenic emissions.

Partnerships for Informal Science Education in the Community (PISEC) is the longstanding JILA-PFC community partnership-based public engagement program. PISEC connects university volunteers with K12 youth to engage in hands-on, inquiry-based science activities and projects through afterschool clubs and in-class project-based mentorship. We seek to support youth STEM identity development and to cultivate and sustain students' interest in STEM by co-creating transformative and empowering experiences with STEM. Simultaneously, we offer valuable teaching, science communication, and leadership experience for the university participants. In this talk, we will discuss the details of the PISEC program and provide an overview of past and ongoing education research studies on various aspects of the program. We will also have a chance to engage in fun, hands-on activities! We invite all JILAns to attend, whether you have participated in PISEC before or are hearing about it for the first time. Join us to get a taste of JILA-PFC public engagement and learn about opportunities to get involved.

Active systems are driven out of equilibrium by exchanging energy and momentum with their environment. This endows them with anomalous mechanical properties which leads to rich phenomena when active fluids are in contact with boundaries, inclusions, or disordered potentials. Indeed, studies of the mechanical pressure of active fluids and of the dynamics of passive tracers have shown that active systems impact their environment in non-trivial ways, for example, by propelling and rotating anisotropic inclusions. Conversely, the long-ranged density and current modulations induced by localized obstacles show how the environment can have a far-reaching impact on active fluids. This is best exemplified by the propensity of bulk and boundary disorder to destroy bulk phase separation in active matter, showing active systems to be much more sensitive to their surroundings than passive ones.

Since 2019, the CUbit Quantum Seminar Series at the University of Colorado Boulder has been a cornerstone of Colorado’s rapidly expanding quantum innovation ecosystem. Each seminar brings leading quantum scientists, entrepreneurs, and technologists from around the world to campus, creating a rare forum where students, researchers, and industry partners engage directly with the people and ideas shaping the future of quantum technology.

More than a research showcase, the series sparks collaboration, inspires emerging talent, accelerates workforce readiness, and strengthens Colorado’s role as a national leader in quantum science and commercialization. This event continues that tradition—bringing the community together to explore new breakthroughs, exchange perspectives, and advance the region’s quantum momentum.

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

For the last quarter century, experiments at Brookhaven National Laboratory’s  Relativistic Heavy Ion Collider and the LHC at CERN have measured extremely high-energy heavy-ion collisions with the hope of producing the Quark Gluon Plasma (QGP) and extracting its properties. The success of this mission depends critically on combining careful, detailed and thorough measurement with complex multi-component theoretical simulations. I will first review how specific bulk properties are illuminated by specific experimental observables. I will then show how the comparison of these large heterogeneous data sets with computationally expensive models built on high-dimensional model-parameter spaces are rigorously constraining these properties through state-of-the-art Bayesian analysis. The extracted equation of state and chemical compositions are found to be consistent with lattice gauge theory. Other properties, which are not so well calculated on the lattice, such as the opacity and emissivity of QCD radiation, the diffusivity of both light and heavy quarks, and the viscosities have also been extracted. I will review where these determinations currently stand and how well they substantiate the claim of having produced the QGP in the laboratory. 

The dynamics of Earth’s radiation belts remain one of the central challenges in space weather research. Despite decades of satellite observations, predicting when and how the belts will intensify or decay remains difficult. This seminar will discuss recent work combining multi-mission datasets from 36 multi-agency satellites to produce the highest-resolution phase space density (PSD) observations of the outer belt to date, and how these have been used to identify dominant acceleration and loss mechanisms. New developments in data-assimilative modelling through the Radiation Belt Forecasting Model and Framework (RBFMF) will also be discussed, including how diminishing real-time data coverage affects operational hindcasts. The results highlight the need for continuous, strategically placed measurements through the heart of the radiation belts and improved understanding of which orbital configurations most effectively enhance prediction capability.

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

As educators, we would like to prepare our students for 21st century physics careers. Overall, to ensure all students will become successful scientists, physics departments need to be able to provide evidence to make sure that we are reaching these goals. The field of Physics Education Research has made major contributions to various educational practices and materials to reform instruction in order to recruit and retain more students. However, while many research-based instructional strategies in physics have continued to advance, reform in undergraduate physics assessment tools has had limited space in these conversations. In this talk, I will motivate the need for the next generation of physics assessment tools and present a few projects that my physics education research lab at Michigan State University has been working on. In particular, I will discuss our efforts to build a more diverse set of tools to use within our classrooms in order to better understand our students’ learning as well as how we can best support them throughout their time in higher education.

Explore physics and quantum-related research through student showcases and poster sessions. Hear from industry executives Safy Fishov (AMD) and Billy Landuyt (ExxonMobil), and network with engineers from AMD. Food will be provided!

Visit the Research Expo website to RSVP or Register to present a poster:

• Register to present a poster by March 22.
• RSVP to attend by April 3.

TBA

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

The first year of a Ph.D. is our last opportunity to gather students heading into every research area and tell them one long-form story. Because they have just finished an undergrad degree, it is also our first opportunity to focus on the interconnections that make us so happy doing physics, to break out of the silos bounding undergrad courses. Also, many aspects of Physics culture can at last be expressed in concrete form, including symmetry/geometry as the drivers of physical insight. I'll offer an approach that focuses on crazy phenomena that make us ask, "How could anything like that possibly happen at all?" After so much education, students are sometimes shocked at how many such questions remain; some are delighted by how many of them are tractable with ideas that are in their heads, but not fully interconnected yet.

The Will Lab studies quantum systems of ultracold atoms and molecules. The lab cools atoms and molecules to temperatures less than a millionth of a degree above absolute zero, where atomic behavior is fully governed by quantum mechanics. Under these conditions, the lab controls individual quantum particles and their interactions with high precision using atomic physics tools, enabling novel platforms for many-body quantum physics, quantum simulation, quantum computing, and quantum optics. Their work spans from fundamental physics—including the first molecular Bose–Einstein condensates—to applied quantum technologies such as large-scale atomic tweezer arrays, opening new approaches to quantum information science and quantum networking.

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

Condensed matter physics aims to explore and understand various quantum phenomena that emerge from the interactions between nuclei and electrons. Through synthesizing and investigating various crystals, this constructionism approach has led to the discovery of many amazing phenomena, especially when the principles of electron correlation and topology play important roles. The settings of such conventional crystals are often very complicated, making it hard to extract the essential ingredients and understand the underlying physics. In this talk, I will show our efforts on establishing a new paradigm, based on a material known as rhombohedral graphene, which is part of natural graphite. Rhombohedral graphene has the simplest chemistry and structure, yet can be controlled by a set of experimental knobs to exhibit many intriguing phenomena in condensed matter physics. Beyond phenomena that were familiar, I will focus on two newly observed quantum phases of matter, chiral superconductor and fractional quantum anomalous Hall effect. I will show their construction, phenomena, and implications for quantum many-body physics and applications. In the end, I will discuss new opportunities to be explored in this new paradigm.

I will discuss the standards of time and frequency and how these standards have evolved over the centuries. I will present the current definitions of time and frequency and how these definitions are likely to evolve in the coming years.

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

TBA

TBA