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Fault-tolerant quantum computing is required to execute many of the most promising quantum applications. In recent years, numerous error correcting codes, such as the surface code, have emerged which are well suited for current and future limited connectivity 2-D devices. We find quantum memory, particularly resonant cavities with transmon qubits arranged in a 2.5-D architecture, can efficiently implement surface codes with around 20× fewer transmons via this work. We virtualize 2-D memory addresses by storing the code in layers of qubit memories connected to each transmon. Distributing logical qubits across many memories has minimal impact on fault tolerance and results in substantially more efficient logical operations. Virtualized logical qubit (VLQ) systems can achieve fault tolerance comparable to conventional 2-D transmon-only architectures while putting within reach a proof-of-concept experimental demonstration of around ten logical qubits, requiring only 11 transmons and 9 attached cavities.

We provide lessons learned in leveraging existing simulations to conduct human-subjects cybersecurity experiments and develop training for cybersecurity professionals. First, we provide criteria for the evaluation and categorization of existing simulation tools into four categories (competitions, testbeds, tabletop exercises, and simulations used in published research). Following this, eight criteria are offered to evaluate simulations on their suitability for use in experiments. We evaluated one representative product in each category. This paper serves as a resource for practitioners who use simulation as a method of training or evaluation. Further, this work is a starting point for researchers to efficiently find and leverage simulations to conduct cybersecurity research.

Building a quantum computer that surpasses the computational power of its classical counterpart is a great engineering challenge. Quantum software optimizations can provide an accelerated pathway to the first generation of quantum computing applications that might save years of engineering effort. Current quantum software stacks follow a layered approach similar to the stack of classical computers, which was designed to manage the complexity. In this review, we point out that greater efficiency of quantum computing systems can be achieved by breaking the abstractions between these layers. We review several works along this line, including two hardware-aware compilation optimizations that break the quantum Instruction Set Architecture (ISA) abstraction and two error-correction/information-processing schemes that break the qubit abstraction. Last, we discuss several possible future directions., Invited paper by Proceedings of IEEE special issue

Photonic synthetic materials provide an opportunity to explore the role of microscopic quantum phenomena in determining macroscopic material properties. There are, however, fundamental obstacles to overcome — in vacuum, photons not only lack mass, but also do not naturally interact with one another. Here, we review how the superconducting quantum circuit platform has been harnessed in the last decade to make some of the first materials from light. We describe the structures that are used to imbue individual microwave photons with matter-like properties such as mass, the nonlinear elements that mediate interactions between these photons, and quantum dynamic/thermodynamic approaches that can be used to assemble and stabilize strongly correlated states of many photons. We then describe state-of-the-art techniques to generate synthetic magnetic fields, engineer topological and non-topological flat bands and explore the physics of quantum materials in non-Euclidean geometries — directions that we view as some of the most exciting for this burgeoning field. Finally, we discuss upcoming prospects, and in particular opportunities to probe novel aspects of quantum thermalization and detect quasi-particles with exotic anyonic statistics, as well as potential applications in quantum information science. This Review Article surveys the physics of many-body quantum states formed by microwave photons in circuit quantum electrodynamics environments.

Objective The combat identification (CID) abilities of same-gender and mixed-gender dyads were experimentally assessed, along with measures of spatial skills and team communication. Background CID is a high-stakes decision-making task involving discrimination between friendly and enemy forces. Literature on CID is primarily focused on the individual, but the extensive use of teams in the military means that more team-based research is needed in this area. Method After a set of training sessions, 39 dyads were tasked with identifying 10 armored vehicles in a series of pictures and videos. Team communication was recorded, transcribed, and coded for instances of disagreements. Results Analyses indicated that males scored higher on a spatial visualization measure than did females. M-M teams performed significantly better than M-F teams on the CID task, but when spatial ability and team disagreements were added as predictors, the effect of team gender composition became nonsignificant. Spatial ability and team disagreement were significant predictors of team CID performance. Conclusion Results suggest that spatial skills and team disagreement behaviors are more important for team CID performance than a team’s gender composition. To our knowledge, this is the first lab study of team CID. Application This research highlights the importance of understanding both individual differences (e.g., spatial skills) and team processes (e.g., communication) within CID training environments in the military context.

Cybersecurity has large-scale versions of the challenges common to sociotechnical systems; in this high-risk, dynamic environment, attacks on organizations and governments are increasing in frequency, sophistication, and severity. In this paper, we summarize existing understanding of situation awareness in cybersecurity and propose additional factors that reflect emerging technology in the domain, incorporate the rising role of automation in cybersecurity, and are relevant to diverse organizations. To do this, we apply a distributed, sociotechnical systems approach to SA and consider the importance of multiteam cognition. Finally, we describe strategies for measurement to support future empirical research in cybersecurity.

We introduce a simple, widely applicable formalism for designing "error-divisible" two qubit gates: a quantum gate set where fractional rotations have proportionally reduced error compared to the full entangling gate. In current noisy intermediate-scale quantum (NISQ) algorithms, performance is largely constrained by error proliferation at high circuit depths, of which two-qubit gate error is generally the dominant contribution. Further, in many hardware implementations, arbitrary two qubit rotations must be composed from multiple two-qubit stock gates, further increasing error. This work introduces a set of criteria, and example waveforms and protocols to satisfy them, using superconducting qubits with tunable couplers for constructing continuous gate sets with significantly reduced error for small-angle rotations. If implemented at scale, NISQ algorithm performance would be significantly improved by our error-divisible gate protocols., 5 pages main text, 11 pages total, 5 figures main text, 10 figures total, 3 tables in appendix

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 channels. The main challenges in engineering such systems are simultaneously guarding against both bit- and phase-flip errors, and also ensuring high-fidelity qubit control. Although partial noise protection is possible in superconducting circuits relying on a single quantum degree of freedom, the promise of complete protection can only be fulfilled by implementing multimode or hybrid circuits. This Perspective reviews the theoretical principles at the heart of these new qubits, describes recent experiments, and highlights the potential of robust encoding of quantum information in superconducting qubits.

Quantum computing based on superconducting qubits requires the understanding and control of the materials, device architecture, and operation. However, the materials for the central circuit element, the Josephson junction, have mostly been focused on using the AlOx tunnel barrier. Here, we demonstrate Josephson junctions and superconducting qubits employing two-dimensional materials as the tunnel barrier. We batch-fabricate and design the critical Josephson current of these devices via layer-by-layer stacking N layers of MoS2 on the large scale. Based on such junctions, MoS2 transmon qubits are engineered and characterized in a bulk superconducting microwave resonator for the first time. Our work allows Josephson junctions to access the diverse material properties of two-dimensional materials that include a wide range of electrical and magnetic properties, which can be used to study the effects of different material properties in superconducting qubits and to engineer novel quantum circuit elements in the future.