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The performance of quantum computers is hindered by decoherence and crosstalk, which cause errors and limit the ability to perform long computations. Dynamical decoupling is a technique that alleviates these issues by applying carefully timed pulses to individual qubits, effectively suppressing unwanted interactions. However, as quantum devices grow in size, it becomes increasingly important to minimize the time required to implement dynamical decoupling across the entire system. Here, we present ``Chromatic-Hadamard Dynamical Decoupling'' (CHaDD), an approach that efficiently schedules dynamical decoupling pulses for quantum devices with arbitrary qubit connectivity. By leveraging Hadamard matrices, CHaDD achieves a circuit depth that scales linearly with the chromatic number of the connectivity graph for general two-qubit interactions, assuming instantaneous pulses. This includes ZZ crosstalk, which is prevalent in superconducting qubit devices. CHaDD's scaling represents an exponential improvement over all previous multi-qubit decoupling schemes for devices with connectivity graphs whose chromatic number grows at most polylogarithmically with the number of qubits. For graphs with a constant chromatic number, CHaDD's scaling is independent of the number of qubits. Our results suggest that CHaDD can become a useful tool for enhancing the performance and scalability of quantum computers by efficiently suppressing decoherence and crosstalk across large qubit arrays., Comment: 8 pages, 3 figures; improved general scaling of CHaDD from quadratic to linear, added references

Simulating plasma physics on quantum computers is difficult because most problems of interest are nonlinear, but quantum computers are not naturally suitable for nonlinear operations. In weakly nonlinear regimes, plasma problems can be modeled as wave-wave interactions. In this paper, we develop a quantization approach to convert nonlinear wave-wave interaction problems to Hamiltonian simulation problems. We demonstrate our approach using two qubits on a superconducting device. Unlike a photonic device, a superconducting device does not naturally have the desired interactions in its native Hamiltonian. Nevertheless, Hamiltonian simulations can still be performed by decomposing required unitary operations into native gates. To improve experimental results, we employ a range of error mitigation techniques. Apart from readout error mitigation, we use randomized compilation to transform undiagnosed coherent errors into well-behaved stochastic Pauli channels. Moreover, to compensate for stochastic noise, we rescale exponentially decaying probability amplitudes using rates measured from cycle benchmarking. We carefully consider how different choices of product-formula algorithms affect the overall error and show how a trade-off can be made to best utilize limited quantum resources. This study provides an example of how plasma problems may be solved on near-term quantum computing platforms., Comment: 26 pages, 5 figures

Approximately 450 community colleges nationally are part of formal statewide or national initiatives to implement guided pathways reforms to improve student success, and many other colleges are implementing guided pathways practices on their own. Because guided pathways is a whole-college reform--and because it takes several years to fully implement--it is challenging to evaluate. This paper presents a methodology for assessing the scale of adoption and estimating the causal effects of guided pathways within states and across colleges that have adopted the approach. To measure the scale of adoption of guided pathways practices, we will conduct institutional surveys and phone interviews with college leaders and examine the websites of every community college in Ohio, Tennessee, and Washington (70 institutions total). We plan to use these data to estimate each college's scale of adoption using a rubric with indicators for scale and timing. Drawing on strategies used in K-12 whole-school reform evaluations, we propose to examine pre-reform adoption trends and apply a single interrupted time series design to project what students' early outcomes would have been in the absence of guided pathways. We then propose to use a comparative interrupted time series design (which closely resembles a difference-in-differences approach) to exploit variation in the intensity of guided pathways practices and the timing of their adoption across colleges by comparing early student outcomes in colleges that have adopted guided pathways practices at scale and those that have not or those with a low scale of adoption. [This report was written with Hana Lahr.]

This guide is intended to help community college leaders understand the costs involved in implementing guided pathways reforms and develop plans for funding and sustaining them. It is based on research at six institutions that have implemented large-scale changes based on the guided pathways model, which focuses on supporting students to enter and complete programs of study that lead to good jobs and transfer to four-year college programs. The guide explores the following questions: (1) What are the up-front and recurring costs of guided pathways reforms? (2) How are colleges funding these costs? (3) How are colleges sustaining support for guided pathways practices? and (4) How can college leaders contemplating guided pathways reforms estimate the costs involved and develop a viable plan for funding and sustaining the reforms? All six case study institutions incurred costs above and beyond the status quo, with the largest costs related to hiring, training, and maintaining an adequate number of advisors for case management advising by field. Significant start-up costs also included purchasing or upgrading information systems to support websites with user-friendly program maps, educational planning, case-management advising, and class scheduling. However, college leaders reported that they do not intend to return to old practices--even in response to a crisis of the magnitude of COVID-19--because guided pathways reforms have led to improved outcomes for students and benefited the colleges as businesses. Four colleges reported increased Integrated Postsecondary Education Data System (IPEDS) retention and graduation rates and reductions in non-degree-applicable credits. Moreover, leaders at every college indicated that they were better positioned to respond to the COVID-19 crisis because of changes they made as part of their pathways reforms. This guide outlines steps that college leaders can take to estimate the costs involved in implementing guided pathways and develop a plan for funding and sustaining these reforms. A companion technical paper estimates the overall costs of implementing guided pathways for colleges of various sizes. [For the companion paper, "The Economics of Guided Pathways: Cost, Funding, and Value," see ED609232.]