Chronological feed of everything captured from Steven Girvin.
The paper introduces a normal-ordered Hamiltonian expansion to derive formally exact amplitudes, termed supercoefficients, for arbitrary parametric processes in single-degree-of-freedom driven Josephson circuits like SNAIL and SQUID designs. These supercoefficients encode full circuit topology, nonlinearity, and drive information, enabling strong-drive regime studies with closed-form expressions for stray-inductor-free cases. The framework extends to multi-mode systems, higher-harmonics Josephson models, multi-drive scenarios, and eigenstate bases, demonstrated via Kerr-cat qubit parameter estimation, chaos criteria, and beam-splitter interaction activation.
In a 1D Z2 lattice gauge theory coupled to soft-core bosons at unit filling, strong electric fields and weak on-site interactions induce a bunching state with superextensive energy and macroscopic particle number fluctuations via gauge-mediated resonant pair hopping. Increasing on-site interactions transitions this to a pair superfluid with finite superfluid density and power-law pair correlations, then to an incompressible pair Mott insulator at large interactions due to gauge-constrained effective interactions. Weak fields yield a plasma phase with balanced even-odd boson occupations and large short-range correlations. These phases, challenging for classical numerics, suit quantum simulation in circuit QED, neutral atoms, and trapped ions.
This paper introduces novel numerical techniques for constructing time-dependent Hamiltonian models of microwave-driven superconducting Josephson circuits. These techniques leverage classical microwave simulations, executed in finite element solvers, to accurately capture device dynamics. Unlike previous methods, this approach does not rely on a lumped-element description, allowing for characterization of circuits with arbitrary geometries and complex electromagnetic environments. The methods are crucial for optimizing circuit designs and advancing superconducting quantum computing applications.
This paper reviews the potential of solid-state nuclear clocks utilizing the low-energy 8.4 eV nuclear transition in Thorium-229. The authors discuss the fundamental physics, technological hurdles, and current limitations of atomic clocks, contrasting them with the prospective advantages of a Th-229 based system. Key challenges include mitigating inhomogeneous broadening caused by crystal defects and dopants.
This paper introduces Non-Abelian Quantum Signal Processing (NQSP), an extension of traditional QSP that utilizes non-commuting control parameters for hybrid continuous- and discrete-variable quantum systems. NQSP, specifically through the Gaussian-Controlled-Rotation (GCR) sequence, demonstrates significant speedup and performance comparable to state-of-the-art abelian QSP methods. This development is crucial for robust quantum control, enabling high-fidelity state preparation and error-corrected operations in next-generation quantum computing architectures.