Note on simple and consistent gateset characterization including calibration and decoherence errors

Building high-fidelity quantum computers requires efficient methods for the characterization of gate errors that provide actionable information that may be fed back into engineering efforts. Extraction of realistic error models is also critical to accurate simulation and design of quantum circuits, including those used in quantum error correction. We provide a method for determining the parameters corresponding to decoherence in a model gateset. We demonstrate that this method is robust to SPAM and pulse area errors, and describe a simple and intuitive method for interpreting the quality and precision of the resulting error model

Time reversal symmetry breaking in two-dimensional non-equilibrium viscous fluids

We study the rheological signatures of departure from equilibrium in two-dimensional viscous fluids with and without internal spin. Under the assumption of isotropy, we provide the most general linear constitutive relations for stress and couple stress in terms of the velocity and spin fields. Invoking Onsager's regression hypothesis for fluctuations about steady states, we derive the Green-Kubo formulae relating the transport coefficients to time correlation functions of the fluctuating stress. In doing so, we verify the claim that one of the non-equilibrium transport coefficients, the odd-viscosity, requires time reversal symmetry breaking in the case of systems without internal spin. However, the Green-Kubo relations for systems with internal spin also show that there is a possibility for non-vanishing odd viscosity even when time reversal symmetry is preserved. Furthermore, we find that breakdown of equipartition in non-equilibrium steady states results in the decoupling of the two rotational viscosities relating the vorticity and the internal spin

Statistical Mechanics of Transport Processes in Active Fluids II: Equations of Hydrodynamics for Active Brownian Particles

We perform a coarse-graining analysis of the paradigmatic active matter model, Active Brownian Particles, yielding a continuum description in terms of balance laws for mass, linear and angular momentum, and energy. The derivation of the balance of linear momentum reveals that the active force manifests itself directly as a continuum-level body force proportional to an order parameter-like director field, which therefore requires its own evolution equation to complete the continuum description of the system. We derive this equation, demonstrating in the process that bulk currents may be sustained in homogeneous systems only in the presence of inter-particle aligning interactions. Further, we perform a second coarse-graining of the balance of linear momentum and derive the expression for active or swim pressure in the case of mechanical equilibrium.Comment: 9 pages, 3 appendices with derivation

Ideology and the Study of Judicial Behavior

http://deepblue.lib.umich.edu/bitstream/2027.42/116253/1/IdPsychLaw.pd

The Bush Imprint on the Supreme Court: Why Conservatives Should Continue to Yearn and Liberals Should Not Fear

http://deepblue.lib.umich.edu/bitstream/2027.42/116213/1/tulsa08.pd

Circuit Effects: How the Norm of Federal Judicial Experience Biases the Supreme Court

For the first time in American history, all nine Justices of the U.S. Supreme Court came to their positions directly from U.S. courts of appeals. As new vacancies arise in the coming years, should the President continue to look to the circuits for Supreme Court nominees? Commentators disagree on the answer. Those who support the current practice claim that the Senate is more likely to confirm nominees with judicial experience. Proponents also argue that former federal judges are more likely to reach decisions based on precedent rather than on their own ideological values. Those opposed to current practice point to the costs of elevating federal judges. Among the most pernicious may be “circuit effects,” or the possibility that former U.S. courts of appeals judges are predisposed toward affirming decisions of the institutions they just left—their respective federal circuits. We enter this debate not by rehashing the existing arguments, but by exploring them empirically. From our analyses, a clear conclusion emerges: the benefits of drawing Supreme Court Justices from the circuits are, at best, overstated, while the costs are, at a minimum, understated. Indeed, the data reveal a strong predilection on the part of Justices with federal judicial experience to rule in favor of their respective home court. For some, the attachment is so strong that they are twice as likely to affirm decisions coming from their former circuit as decisions coming from all others. Even more striking is the advantage now enjoyed by the U.S. Court of Appeals for the District of Columbia—the former home of four sitting Supreme Court Justices. An obvious antidote is for the President to end the practice of appointing Supreme Court Justices from the circuits, and instead turn to the nation’s law schools, law firms, legislatures, executives, and state courts. A less obvious, though no less plausible, remedy is for the President to select nominees from circuits underrepresented on the Court.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116212/1/penn09.pd