paper / stevengirvin / Dec 23
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.
quantum-computingjosephson-circuitsmicrowave-driveshamiltonian-modelingsuperconducting-circuitsquantum-systemsnumerical-methods
“Existing numerical methods like black-box quantization (BBQ) and energy-participation ratio (EPR) are insufficient for modeling driven superconducting circuits and do not account for noise and dissipation from microwave ports.”
paper / stevengirvin / Nov 17
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.
solid-state-physicsnuclear-clocksthorium-229atomic-physicsmaterials-sciencequantum-metrology
“Solid-state nuclear clocks based on Thorium-229 (Th-229) offer a promising alternative to current atomic clock technology.”
paper / stevengirvin / Apr 28
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.
quantum-signal-processingquantum-controlquantum-computingquantum-error-correctionnon-abelian-qsphybrid-quantum-systems
“Non-abelian QSP (NQSP) extends traditional QSP by using non-commuting control parameters.”
paper / stevengirvin / Mar 5
A one-dimensional Z₂ lattice gauge theory coupled to soft-core bosonic matter at unit filling produces a rich ground-state phase diagram driven by gauge-field-mediated resonant pair hopping and single-particle confinement. Four distinct phases emerge: a bunching state with superextensive energy and macroscopic number fluctuations, a pair superfluid with power-law-decaying correlations, an incompressible pair Mott insulator, and a plasma-like region with large short-range single-boson correlations. The bunching state's large number fluctuations make it intractable for classical numerical methods, motivating experimental realization on hybrid boson-qubit platforms such as circuit QED, neutral atoms, and trapped ions.
lattice-gauge-theoryquantum-many-bodyphase-diagramquantum-simulationcondensed-matterbosonic-matterquantum-gases
“The Z₂ lattice gauge theory produces a bunching state with superextensive energy and macroscopic particle number fluctuations at strong electric field strengths and weak on-site interactions.”
paper / stevengirvin / Jan 14
This paper introduces a systematic normal-ordered expansion for the Hamiltonian of parametrically driven superconducting circuits. This approach provides formally exact amplitudes for parametric processes, enabling optimization of circuit designs and study in the strong drive regime. It is applicable to both single and multi-degree-of-freedom circuits, offering a versatile tool for analyzing complex quantum systems.
quantum-physicsjosephson-circuitsparametric-processessuperconducting-circuitsquantum-computingkerr-cat-qubits
“A general approach for analyzing arbitrary parametric processes in Josephson circuits within a single degree of freedom approximation leads to formally exact amplitudes ('supercoefficients').”