Decoherence errors, caused by the interaction of quantum systems with their environment, pose a major challenge for the practical implementation of quantum computing. Accurately modeling these errors is essential for analyzing and improving gate fidelities. While Lindblad master equation and its several generalizations have been proposed, there is still ongoing exploration for simpler and more […]
Together with theory collaborators from UChicago we analyze driven quantum systems subject to non-Markovian noise. These systems are typically difficult to model even if the noise is classical. We present a systematic method based on generalized cumulant expansions for deriving a time-local master equation for such systems. This master equation has an intuitive form that […]
The use of time-dependent flux is ubiquitous in the context of circuit quantum electrodynamics. It is critical to accurately model time-dependent flux in circuit Hamiltonians, which is what Xinyuan at al. did in our previous work. Working with Houck lab in Princeton, we provide experimental verification of what the flux allocation should be in the […]
Along with coworkers from the Schuster lab at UChicago, we introduce a coupling scheme for low frequency fluxonium qubits that allows for high-fidelity entangling gates. Long coherence times, large anharmonicity and robust charge-noise insensitivity render fluxonium qubits an interesting alternative to transmons. Recent experiments have demonstrated record coherence times for low-frequency fluxonia. Here, we propose […]
We present a formalism to quantize a general superconducting circuit with Josephson junctions. The formalism is amenable to an algorithmic implementation and we present an extension Circuit to the scqubits package which deals with a generic superconducting circuit. This algorithm is able to identify all the degrees of freedom and their boundary conditions. Moreover, the non dynamical […]
Together with theory collaborators from UChicago we analyze driven quantum systems subject to non-Markovian noise. These systems are typically difficult to model even if the noise is classical. We present a systematic method based on generalized cumulant expansions for deriving a time-local master equation for such systems. This master equation has an intuitive form that […]
Along with coworkers from the Schuster lab at UChicago, we introduce a coupling scheme for low frequency fluxonium qubits that allows for high-fidelity entangling gates. Long coherence times, large anharmonicity and robust charge-noise insensitivity render fluxonium qubits an interesting alternative to transmons. Recent experiments have demonstrated record coherence times for low-frequency fluxonia. Here, we propose […]
The development of new superconducting circuits and the improvement of existing ones rely on the accurate modeling of spectral properties which are key to achieving the needed advances in qubit performance. Systematic circuit analysis at the lumped-element level, starting from a circuit network and culminating in a Hamiltonian appropriately describing the quantum properties of the […]
scqubits is an open-source Python package for simulating and analyzing superconducting circuits. It provides convenient routines to obtain energy spectra of common superconducting qubits, such as the transmon, fluxonium, flux, cos(2ϕ) and the 0-π qubit. scqubits also features a number of options for visualizing the computed spectral data, including plots of energy levels as a function of external parameters, […]
Artificial atoms realized by superconducting circuits offer unique opportunities to store and process quantum information with high fidelity. Among them, implementations of circuits that harness intrinsic noise protection have been rapidly developed in recent years. These noise-protected devices constitute a new class of qubits in which the computational states are largely decoupled from local noise […]