Reliability and reproducibility of Atlas information

We discuss the reliability and reproducibility of much of the information contained in the Atlas of Finite Groups

Quantum digital cooling

We introduce a method for digital preparation of ground states of a simulated Hamiltonians, inspired by cooling in nature and adapted to leverage the capabilities of digital quantum hardware. The cold bath is simulated by a single ancillary qubit, which is reset periodically and coupled to the system non-perturbatively. Studying this cooling method on a 1-qubit system toy model allows us to optimize two cooling protocols based on weak-coupling and strong-coupling approaches. Extending the insight from the 1-qubit system model, we develop two scalable protocols for larger systems. The LogSweep protocol extends the weak-coupling approach by sweeping energies to resonantly match any targeted transition. It demonstrates the ability to prepare an approximate ground state of tranverse-field Ising chains in the ferromangetic and critical phases, with an error that can be made polynomially small in time. The BangBang protocol extends the strong-coupling approach, and exploits a heuristics for local Hamiltonians to maximise the probability of de-exciting system transitions in the shortest possible time. Although this protocol does not promise long-time convergence, it allows for a rapid cooling to an approximation of the ground state, making this protocol appealing for near-term simulation applications.Comment: 8 pages, 8 figure

Engaging Students Engaging Industry Engaging Enterprise

A reflective piece on how a small team of students and academics gained more awareness of their own sense of enterprise and creativity. The case study examines the phases and crisis points of the whole event process and identifies some of the key learning outcomes for all involved

Many-particle Majorana bound states: derivation and signatures in superconducting double quantum dots

We consider two interacting quantum dots coupled by standard superconductors. We derive an effective Hamiltonian, and show that over a wide parameter range a degenerate ground state can be obtained. An exotique form of Majorana bound states are supported at these degeneracies, and the system can be adiabatically tuned to a limit in which it is equivalent to the one-dimensional wire model of Kitaev. We give the form of a Majorana bound state in this system in the strong interaction limit in the many-particle picture. We also study the Josephson current in this system, and demonstrate that a double slit-like pattern emerges in the presence of an extra magnetic field. This pattern is shown to disappear with increasing interaction strength, which is able to be explained as the current being carried by chargeless Majorana modes.Comment: 13 pages, 7 figures. Updated paper includes more details regarding the derivation of the effective Hamiltonia

Optimizing the information extracted by a single qubit measurement

We consider a quantum computation that only extracts one bit of information per quantum state preparation. This is relevant for error mitigation schemes where the remainder of the system is measured to detect errors. We optimize the estimation of the expectation value of an operator by its linear decomposition into bitwise-measurable terms. We prove that optimal decompositions must be in terms of reflections with eigenvalues $\pm1$. We find the optimal reflection decomposition of a fast-forwardable operator, and show a numerical improvement over a simple Pauli decomposition by a factor $N^{0.7}$.Comment: 14 pages, 4 figure

Online Interstate Student Diplomats Discuss What Justifies War: 'We don't want people to die, but we don't want to lose our oil'

This is the publisher's version, also found at http://www.ccsenet.org/journal/index.php/jel/article/view/17286Given that most research in online discussion addresses asynchronous discussions and that middle school students receive little opportunity to engage in sustained, substantive dialogues, there is a need to develop and pilot ways to instructional support students in sustained, online synchronous discussions about public policy issues such as why nations go to war. This article presents: a blended learning instructional model for an online synchronous discussion that was developed and piloted; instructional and logistical issues raised with the model; suggestions on conducting interschool online discussions to promote students’ online voice; and, samples of students’ thinking about what justifies war

Metaliteracy as Pedagogical Framework for Learner-Centered Design in Three MOOC Platforms: Connectivist, Coursera and Canvas

This article examines metaliteracy as a pedagogical model that leverages the assets of MOOC platforms to enhance self-regulated and self-empowered learning. Between 2013 and 2015, a collaborative teaching team within the State University of New York (SUNY) developed three MOOCs on three different platforms—connectivist, Coursera and Canvas—to engage with learners about metaliteracy. As a reframing of information literacy, metaliteracy envisions the learner as an active and metacognitive producer of digital information in online communities and social media environments (Mackey & Jacobson, 2011; 2014). This team of educators, which constitutes the core of the Metaliteracy Learning Collaborative, used metaliteracy as a lens for applied teaching and learning strategies in the development of a cMOOC and two xMOOCs. The metaliteracy MOOCs pushed against the dominant trends of lecture-based, automated MOOC design towards a more learner-centered pedagogy that aligns with key components of metaliteracy

Software mitigation of coherent two-qubit gate errors

Two-qubit gates are important components of quantum computing. However, unwanted interactions between qubits (so-called parasitic gates) can be particularly problematic and degrade the performance of quantum applications. In this work, we present two software methods to mitigate parasitic two-qubit gate errors. The first approach is built upon the Cartan's KAK decomposition and keeps the original unitary decomposition for the error-free native two-qubit gate. It counteracts a parasitic two-qubit gate by only applying single-qubit rotations and therefore has no two-qubit gate overhead. We show the optimal choice of single-qubit mitigation gates. The second approach applies a numerical optimisation algorithm to re-compile a target unitary into the error-parasitic two-qubit gate plus single-qubit gates. We demonstrate these approaches on the CPhase-parasitic iSWAP-like gates. The KAK-based approach helps decrease unitary infidelity by a factor of 3 compared to the noisy implementation without error mitigation. When arbitrary single-qubit rotations are allowed, recompilation could completely mitigate the effect of parasitic errors but may require more native gates than the KAK-based approach. We also compare their average gate fidelity under realistic noise models, including relaxation and depolarising errors. Numerical results suggest that different approaches are advantageous in different error regimes, providing error mitigation guidance for near-term quantum computers

Software mitigation of coherent two-qubit gate errors

Two-qubit gates are important components of quantum computing. However, unwanted interactions between qubits (so-called parasitic gates) can be particularly problematic and degrade the performance of quantum applications. In this work, we present two software methods to mitigate parasitic two-qubit gate errors. The first approach is built upon the Cartan's KAK decomposition and keeps the original unitary decomposition for the error-free native two-qubit gate. It counteracts a parasitic two-qubit gate by only applying single-qubit rotations and therefore has no two-qubit gate overhead. We show the optimal choice of single-qubit mitigation gates. The second approach applies a numerical optimisation algorithm to re-compile a target unitary into the error-parasitic two-qubit gate plus single-qubit gates. We demonstrate these approaches on the CPhase-parasitic iSWAP-like gates. The KAK-based approach helps decrease unitary infidelity by a factor of 3 compared to the noisy implementation without error mitigation. When arbitrary single-qubit rotations are allowed, recompilation could completely mitigate the effect of parasitic errors but may require more native gates than the KAK-based approach. We also compare their average gate fidelity under realistic noise models, including relaxation and depolarising errors. Numerical results suggest that different approaches are advantageous in different error regimes, providing error mitigation guidance for near-term quantum computers