JILA Science Seminar

Quantum-Enhanced Sensing in Solid-State and Molecular Spin Systems

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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.

Improving Two-Qubit Gate Fidelity in Arrays of 171Yb

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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.

Developing ultralow-loss diamond nanomechanics for force and gravitational sensing

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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.

Let’s Twist Again: Locally Interacting Spins for Metrological Entanglement

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A paradigmatic model in quantum metrology is the one-axis twisting Hamiltonian, comprising all-to-all Ising interactions that dynamically generate resources for entanglement-enhanced spectroscopy, notably squeezed and Schrödinger cat states.  Generalizing this approach to systems with local interactions significantly expands the range of platforms amenable to quantum-enhanced sensing.  I will report on past and ongoing experiments leveraging Rydberg interactions to realize locally interacting variants of one-axis twisting.

Kapitza pendulums for many-body physics and precision measurement

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The Kapitza pendulum, an inverted pendulum that is inherently unstable yet dynamically stabilized by high-frequency modulation of its pivot, is perhaps the most iconic example of dynamical stabilization of a single-particle system. Dynamical stabilization in the quantum many-body regime, however, remains largely unexplored, especially from an experimental perspective. In the first part of this talk, I will discuss experiments on ultracold atoms confined using time-periodic attractive and repulsive Gaussian potentials, the time average of which is zero [1] or positive.

Longitudinal Spectroscopy of 88Sr in a Moving Optical Lattice for Zero-Dead-Time Optical Lattice Clock

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Optical lattice clocks that interrogates N atoms for an interrogation time T can, in principle, reach the quantum-projection-noise (QPN) instability σ_y (τ)∼1/(πν_0 T√Nτ), with ν_0 the clock frequency and τ the averaging time. In practice, however, dead time between preparation and readout aliases the local-oscillator (LO) frequency noise (Dick effect [1]), so the achievable instability is set by the LO noise spectrum and the duty cycle rather than by the QPN limit. This motivates zero-dead-time (ZDT) operation, which removes aliasing by maintaining continuous interrogation.

Life After JILA Seminar

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Jayson Stewart shares his personal journey from JILA to ASML and what surprised him most about moving from academia into industry. The talk is intentionally light on technical details and focuses on real-world lessons and how life at JILA prepares one for a career with impact. Expect candid reflections, practical advice, and plenty of time for Q&A.​

Optimal control of mechanical systems in the quantum regime

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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.

Trapping circular Rydberg states of strontium in optical tweezers at 4K

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Rydberg atoms in optical tweezers have become a leading platform for both quantum simulation and quantum computing. However, they are often limited by their relatively short lifetime of a few tens of microseconds. One way to overcome this limitation is to use Rydberg atoms with maximum angular momentum (m = l = n-1), known as circular states. When placed in a cryogenic environment, these states can exhibit lifetimes of several milliseconds. Circular states of alkaline-earth-like atoms offer additional advantages.