All Scheduled Events

A quantum system undergoing periodic driving can exhibit unusual behavior and properties: dynamical localization, Floquet-engineered band structures, and deeply out-of-equilibrium steady states. We apply three different drive schemes to ultracold atoms to probe the consequences and applications of such dynamics. In the first experiment, a condensate subjected to a periodically pulsed optical lattice enabled the first observation of the quantum boomerang effect, whereby wavepackets launched into a disordered medium counterintuitively turn around and return to their initial position. In the second experiment, amplitude modulation of an optical lattice creates "magic" band structures enabling a novel noise-immune protocol for trapped atom interferometry. In the final experiment, atoms between movable repulsive optical barriers simulate an optical Fabry-Pérot cavity with a relativistically accelerated mirror. Results confirm theoretical predictions that photons in such a strongly driven cavity accumulate into a single bright trajectory. This phenomenon mimics the evolution of light cones at event horizons and supports applications in pulse generation and signal compression.

The next decade will be a phase transition for observational cosmology, with upcoming imaging/spectroscopic/cosmic microwave/radio surveys mapping the sky at unprecedented precision. In this talk I will describe observational and astrophysical challenges for unlocking the cosmological information in each of these data sets individually. I will further detail how comprehensive multi-probe approaches can elevate next decade’s cosmological analyses to a new level of constraining power and robustness.

Quantum materials embedded into devices have been observed to host a wide variety of quantum phases that can exhibit intriguing properties, like dissipationless transport, magnetism, or fractionalized carriers. Understanding the conditions under which these phenomena emerge is of great fundamental interest and important for deterministically designing materials for new applications. In these device-integrated quantum materials, the macroscopic responses are not solely due to the intrinsic interactions of the materials. Instead, these interactions, and the resulting ground state physics, are modified by the specifics of the device integration. In this talk, I will discuss how integrated quantum materials form sub-wavelength cavities due to their micron-size, confining low-energy light into the near field. I will introduce time-domain on-chip THz spectroscopy as a technique to capture the cavity electrodynamics, probing the response of integrated materials to light on their natural frequency (~THz/meV) scales. With this technique we can demonstrate ultrastrong light-matter hybridization in a graphene gate-tunable van der Waals heterostructure, and probe electron-hole asymmetries in bilayer graphene aligned to hBN. These studies lay the groundwork for studying a wide range of low-energy quantum phases and wielding light-matter coupling as a new control parameter for engineering thermodynamic ground states.

Ultrafast optical excitation has opened a new frontier in the control of quantum materials, enabling the emergence of coherent phases from strongly fluctuating states. Striking demonstrations include light-induced ferroelectric order in quantum paraelectrics and transient superconductivity emerging from precursor incoherent pairs. Developing a microscopic understanding of these phenomena is challenging due to the complex role of quantum fluctuations far from equilibrium, requiring new strategies to manipulate and directly probe them using ultrashort light pulses. In the first part of my seminar, I will investigate how the magnetic fluctuations in a quantum spin liquid enable the emergence of an optically driven coherent electronic response. Using optical pump– terahertz probe spectroscopy on the organic quantum spin liquid candidate κ-(BEDT-TTF)2Cu2(CN)3, we observe a transient inductive response that signals the formation of a coherent condensate of bosonic charge excitations arising from spin–charge fractionalization. In the second part, I will discuss a new experimental approach to access the fluctuations governing these nonequilibrium states. I will introduce Ultrafast Quantum Optical Tomography, a technique combining ultrafast spectroscopy and quantum optics. The method measures the photon-number distribution of few-photon probe pulses, revealing intrinsically quantum correlations imprinted by the material onto the optical noise. Our studies provide a framework for simultaneously controlling and measuring quantum fluctuations on ultrafast timescales, offering new insights into the engineering of nonequilibrium phases of matter and the development of quantum optoelectronic technologies.

Quantum technologies promise to revolutionize information processing and precision measurement tasks. Key to these applications is the generation of many-body entanglement, which describes correlations between particles that cannot be explained classically. Whereas conventional quantum algorithms — such as Shor’s algorithm for factoring large numbers — rely on highly structured patterns of entanglement, in this talk I will discuss `scrambled' quantum states featuring entanglement that is random and unstructured. These scrambled states can be generated from short random quantum circuits with randomly chosen gates at each timestep. Despite their lack of structure, I will demonstrate how the resulting many-body states can be harnessed for precision metrology applications and for establishing tests of quantum advantage over classical hardware.

A central goal of Quantum Information Science (QIS) is to harness entanglement for practical advantage. While much of the public attention on QIS has focused on quantum computing, the quantum metrology community has made tremendous progress in developing strategies and platforms for surpassing classical limits on measurement precision. Spin squeezing has emerged as one of the most promising routes to quantum-enhanced precision in atomic clocks, magnetometers, and inertial sensors. While spin squeezing has been extensively studied for infinite-range and homogeneous interactions, recent experimental realizations in finite-range platforms such as trapped ions and Rydberg arrays have opened the door to scalable squeezing by exploiting the spatiotemporal control, significantly broadening the scope of experimentally accessible platforms. In this talk, I will present my work on entanglement generation in bilayers of power-law interacting spin models, where spatiotemporal control of the interactions enables significant improvements in sensitivity scaling over conventional approaches. I will first show how Floquet-engineered spatially anisotropic interactions can improve the metrological scaling from the standard quantum limit (1/√N) to the ultimate Heisenberg limit (1/N). I will then demonstrate that the squeezing dynamics hosts a dynamical phase transition between a fully collective phase with Heisenberg-limited squeezing and a partially collective phase with scalable squeezing. This transition is explained within the framework of nonequilibrium critical phenomena through universal scaling of the full-time dynamics. Finally, I will discuss ongoing work examining the robustness and scope of this universality, including the role of lattice geometry, dimensionality, and interaction engineering in shaping the phase diagram and the critical scaling. These results are relevant to current experiments with Rydberg arrays, polar molecules, and trapped ions, and point toward broader connections between entanglement generation and nonequilibrium universality classes.