Universal Kardar-Parisi-Zhang Dynamics in Integrable Quantum Systems.

Although the Bethe ansatz solution of the spin-1/2 Heisenberg model dates back nearly a century, the anomalous nature of its high-temperature transport dynamics has only recently been uncovered. Indeed, numerical and experimental observations have demonstrated that spin transport in this paradigmatic model falls into the Kardar-Parisi-Zhang (KPZ) universality class. This has inspired the significantly stronger conjecture that KPZ dynamics, in fact, occur in all integrable spin chains with non-Abelian symmetry. Here, we provide extensive numerical evidence affirming this conjecture. Moreover, we observe that KPZ transport is even more generic, arising in both supersymmetric and periodically driven models. Motivated by recent advances in the realization of SU(N)-symmetric spin models in alkaline-earth-based optical lattice experiments, we propose and analyze a protocol to directly investigate the KPZ scaling function in such systems.

Symmetry-Enhanced Boundary Qubits at Infinite Temperature.

The Z_{2}×Z_{2} symmetry-protected topological (SPT) phase hosts a robust boundary qubit at zero temperature. At finite energy density, the SPT phase is destroyed and bulk observables equilibrate in finite time. Nevertheless, we predict parametric regimes in which the boundary qubit survives to arbitrarily high temperature, with an exponentially longer coherence time than that of the thermal bulk degrees of freedom. In a dual picture, the persistence of the qubit stems from the inability of the bulk to absorb the virtual Z_{2}×Z_{2} domain walls emitted by the edge during the relaxation process. We confirm the long coherence times via exact diagonalization and connect it to the presence of a pair of conjugate almost strong zero modes. Our results provide a route to experimentally construct long-lived coherent boundary qubits at infinite temperature in disorder-free systems. To this end, we propose and analyze an implementation using a Rydberg optical-tweezer array and demonstrate that the difference between edge- and bulk-spin autocorrelators can be distinguished on timescales significantly shorter than the typical coherence time.

Quantum gas microscopy of Kardar-Parisi-Zhang superdiffusion.

The Kardar-Parisi-Zhang (KPZ) universality class describes the coarse-grained behavior of a wealth of classical stochastic models. Surprisingly, KPZ universality was recently conjectured to also describe spin transport in the one-dimensional quantum Heisenberg model. We tested this conjecture by experimentally probing transport in a cold-atom quantum simulator via the relaxation of domain walls in spin chains of up to 50 spins. We found that domain-wall relaxation is indeed governed by the KPZ dynamical exponent z = 3/2 and that the occurrence of KPZ scaling requires both integrability and a nonabelian SU(2) symmetry. Finally, we leveraged the single-spin-sensitive detection enabled by the quantum gas microscope to measure an observable based on spin-transport statistics. Our results yield a clear signature of the nonlinearity that is a hallmark of KPZ universality.

Improving the accountability of California's public substance abuse treatment system through the implementation of performance models.

Improving the care for individuals with substance use disorders is a national health policy priority. Like other parts of the health care system, the addiction field is under pressure for higher accountability-more efficient use of treatment resources, the delivery of quality services, and the production of positive client outcomes. This introductory article highlights the importance of the collection of articles being published in this special issue as they describe California's efforts toward making the alcohol and drug (AOD) treatment system more accountable and effective.

Improving public addiction treatment through performance contracting: the Delaware experiment.

In fiscal 2002, Delaware replaced traditional cost-reimbursement contracts with performance-based contracts for all outpatient addiction treatment programs. Incentives included 90% capacity utilization and active patient participation in treatment. One of the programs failed to meet requirements. Strategies adopted by successful programs included extended hours of operation, facility enhancements, salary incentives for counselors, and two evidence-based therapies (MI and CBT). Average capacity utilization from 2001 to 2006 went from 54% to 95%; and the average proportion of patients' meeting participation requirements went from 53% to 70%--with no notable changes in the patient population. We conclude that properly designed, program-based contract incentives are feasible to apply, welcomed by programs and may help set the financial conditions necessary to implement other evidence-based clinical efforts; toward the overall goal of improving addiction treatment.

Reconsidering the evaluation of addiction treatment: from retrospective follow-up to concurrent recovery monitoring.

Historically, addiction treatments have been delivered and evaluated under an acute-care format. Fixed amounts or durations of treatment have been provided and their effects evaluated 6-12 months after completion of care. The explicit expectation of treatment has been enduring reductions in substance use, improved personal health and social function, generally referred to as 'recovery'. In contrast, treatments for chronic illnesses such as diabetes, hypertension and asthma have been provided for indeterminate periods and their effects evaluated during the course of those treatments. Here the expectations are for most of the same results, but only during the course of continuing care and monitoring. The many similarities between addiction and mainstream chronic illnesses stand in contrast to the differences in the ways addiction is conceptualized, treated and evaluated. This paper builds upon established methods of during-treatment evaluation developed for the treatment of other chronic illnesses and suggests a parallel evaluation system for out-patient, continuing-care forms of addiction treatment. The suggested system retains traditional patient-level, behavioral outcome measures of recovery, but suggests that these outcomes should be collected and reported immediately and regularly by clinicians at the beginning of addiction treatment sessions, as a way of evaluating recovery progress and making decisions about continuing care. We refer to this paradigm as 'concurrent recovery monitoring' and discuss its potential for producing more timely, efficient, clinically relevant and accountable evaluations.

Results of a statewide evaluation of "paperwork burden" in addiction treatment.

This article chronicles three steps taken by research, clinical, and state staff toward assessing, evaluating, and streamlining clinical and administrative paperwork at all public outpatient addiction treatment programs in one state. The first step was an accounting of all paperwork requirements at each program. The second step included the development of time estimates for the paperwork requirements; synthesis of information across sites; providing written evaluation of the need, utility, and redundancy of all forms (paperwork) collected; and suggestions for eliminating unused or unnecessary data collection and streamlining the remaining data collection. Thirdly, the state agency hosted a meeting with the state staff, researchers, and staff from all programs and agencies with state-funded contracts and took action. Paperwork reductions over the course of a 6-month outpatient treatment episode were estimated at 4 to 6 hours, with most of the time burden being eliminated from the intake process.