Fundamental limits on low-temperature quantum thermometry with finite resolution

While the ability to measure low temperatures accurately in quantum systems is important in a wide range of experiments, the possibilities and the fundamental limits of quantum thermometry are not yet fully understood theoretically. Here we develop a general approach to low-temperature quantum thermometry, taking into account restrictions arising not only from the sample but also from the measurement process. We derive a fundamental bound on the minimal uncertainty for any temperature measurement that has a finite resolution. A similar bound can be obtained from the third law of thermodynamics. Moreover, we identify a mechanism enabling sub-exponential scaling, even in the regime of finite resolution. We illustrate this effect in the case of thermometry on a fermionic tight-binding chain with access to only two lattice sites, where we find a quadratic divergence of the uncertainty. We also give illustrative examples of ideal quantum gases and a square-lattice Ising model, highlighting the role of phase transitions.Comment: Published version. Main text: 12 pages, 5 figures; see also related work by K. Hovhannisyan and L. A. Correa at arXiv:1712.0308

Exploring the Art of Connections: Directing Sarah Ruhl\u27s Dead Man\u27s Cell Phone

In the March of 2014, the Department of Theatre and Dance at Bucknell University selected me to conceive and direct a production of Dead Man\u27s Cell Phone by Sarah Ruhl. This production would be the winter Main Stage show of the university\u27s artistic season in February 2015. This project would not only serve as an honors thesis project, but also as a THEA 319 Independent Study for the culminating experience of my theatre degree. In preparation for this project, I conducted significant research of both the play itself and the initial design concepts that I felt best supported the piece. I also set out to accomplish two goals: first to direct a piece that would resonate and speak to an audience consisting of my generation and the Bucknell community, and second, to accomplish, as the director, the establishment of a strong and productive ensemble. Working with an advisor and a production team consisting of faculty, staff and students, I became the leader of a yearlong process that included holding auditions for the Bucknell student body, leading and designing five weeks of workshops and rehearsals, and ultimately ensuring a successful run of four shows. The script book for Sarah Ruhl\u27s Dead Man\u27s Cell Phone opens with an epigraph of a quote from A Tale of Two Cities by Charles Dickens. He writes, every human creature is constituted to be that profound secret and mystery to every other. Dead Man\u27s Cell Phone captures the essence of this quote, as protagonist Jane and the audience begin to learn the profound secrets and mysteries of a dead man\u27s life. In our daily lives of classes, meetings, work, personal commitments, and relationships, we journey through the lives of many other people. We see ourselves as always connected, always part of a community- but could that be wrong? Could we, members of the technological age, be more isolated than ever before? How do we have so much information available to us yet still feel we know so little? How do we have so many friends and acquaintances and yet Dickens\u27 assertion that, the three passengers shut up in the narrow compass of one lumbering old mail-coach; they were mysteries to one another, as complete as if each had been in his own coach¿ often still holds true (Ruhl 2008)? This is why I have taken on this show and why I have decided to explore the art of human connections. I wanted to direct this piece at Bucknell because I believe many Bucknell community members can move through our time here meeting many people but only truly knowing a few. This thesis will explore my process as I perused these artistic endeavors

Humankapital, demographische Merkmale, Charakter des Unternehmers und Teamgründungen als Erfolgsfaktoren bei Jungunternehmen der Beherbergungsbranche im Oberwallis

Die Oberwalliser sind sehr engagiert im Bereich Unternehmensgründungen. Es gibt viele Gründerpersonen, welche den Schritt in die Selbständigkeit wagen. Gerade in der Beherber-gungsbranche gibt es viele Unternehmensgründungen. In traditionsreichen Familienunternehmen übernimmt oftmals die jüngere Generation das Unternehmen. Zudem gibt es Personen, welche ihr eigenes Unternehmen gründen. Weiter gibt es Gründerpersonen, welche ein bereits bestehendes Unternehmen kaufen. Verschiedene Wege führen die Gründerpersonen zur Selbständigkeit. So unterschiedlich die Gründe sind, so unterschiedlich sind die Gründerpersonen

Quantum Thermal Machine as a Thermometer

We propose the use of a quantum thermal machine for low-temperature thermometry. A hot thermal reservoir coupled to the machine allows for simultaneously cooling the sample while determining its temperature without knowing the model-dependent coupling constants. In its most simple form, the proposed scheme works for all thermal machines which perform at Otto efficiency and can reach Carnot efficiency. We consider a circuit QED implementation which allows for precise thermometry down to $\sim$15 mK with realistic parameters. Based on the quantum Fisher information, this is close to the optimal achievable performance. This implementation demonstrates that our proposal is particularly promising in systems where thermalization between different components of an experimental setup cannot be guaranteed.Comment: Main text: 5 pages, 4 figures; Supplement: 5 page

Sulphur and Carbon Isotopes as Tracers of Past Sub-seafloor Microbial Activity

Microbial life below the seafloor has changed over geological time, but these changes are often not obvious, as they are not recorded in the sediment. Sulphur (S) isotope values in pyrite extracted from a Plio- to Holocene sequence of the Peru Margin (Ocean Drilling Program, ODP, Site 1229) show a down-core pattern that correlates with the pattern of carbon (C) isotopes in diagenetic dolomite. Early formation of the pyrite is indicated by the mineralogical composition of iron, showing a high degree of pyritization throughout the sedimentary sequence. Hence, the S-record could not have been substantially overprinted by later pyrite formation. The S- and C-isotope profiles show, thus, evidence for two episodes of enhanced microbial methane production with a very shallow sulphate-methane transition zone. The events of high activity are correlated with zones of elevated organic C content in the stratigraphic sequence. Our results demonstrate how isotopic signatures preserved in diagenetic mineral phases provide information on changes of past biogeochemical activity in a dynamic sub-seafloor biosphere

Sustainable product development: Provision of information in early automotive engineering phases

Sustainable product development is an important influencing factor in automotive engineering, whereby a comprehensive evaluation of its efforts and benefits is very complex. In addition, lots of information is not available in advance of mass production. This leads to the question, how results from impact assessment can be transferred to the beginning of the development process, where important decisions about product and production characteristics are made. The present paper discusses approaches for life cycle estimation and decision support in the concept phase of automotive engineering, especially focusing on the design engineer’s requirements. It includes an overview of current development processes and discusses by use of examples different approaches to integrate relevant information concerning sustainable product development in development processes

An Omnidirectional Aerial Manipulation Platform for Contact-Based Inspection

This paper presents an omnidirectional aerial manipulation platform for robust and responsive interaction with unstructured environments, toward the goal of contact-based inspection. The fully actuated tilt-rotor aerial system is equipped with a rigidly mounted end-effector, and is able to exert a 6 degree of freedom force and torque, decoupling the system's translational and rotational dynamics, and enabling precise interaction with the environment while maintaining stability. An impedance controller with selective apparent inertia is formulated to permit compliance in certain degrees of freedom while achieving precise trajectory tracking and disturbance rejection in others. Experiments demonstrate disturbance rejection, push-and-slide interaction, and on-board state estimation with depth servoing to interact with local surfaces. The system is also validated as a tool for contact-based non-destructive testing of concrete infrastructure.Comment: Accepted submission to Robotics: Science and Systems conference 2019. 9 pages, 12 figure

Markovian master equations for quantum thermal machines: local vs global approach

The study of quantum thermal machines, and more generally of open quantum systems, often relies on master equations. Two approaches are mainly followed. On the one hand, there is the widely used, but often criticized, local approach, where machine sub-systems locally couple to thermal baths. On the other hand, in the more established global approach, thermal baths couple to global degrees of freedom of the machine. There has been debate as to which of these two conceptually different approaches should be used in situations out of thermal equilibrium. Here we compare the local and global approaches against an exact solution for a particular class of thermal machines. We consider thermodynamically relevant observables, such as heat currents, as well as the quantum state of the machine. Our results show that the use of a local master equation is generally well justified. In particular, for weak inter-system coupling, the local approach agrees with the exact solution, whereas the global approach fails for non-equilibrium situations. For intermediate coupling, the local and the global approach both agree with the exact solution and for strong coupling, the global approach is preferable. These results are backed by detailed derivations of the regimes of validity for the respective approaches.Comment: Published version. See also the related work by J. Onam Gonzalez et al. arXiv:1707.0922

Optimal work extraction from quantum states by photo-assisted Cooper pair tunneling

The theory of quantum thermodynamics predicts fundamental bounds on work extraction from quantum states. As these bounds are derived in a very general and abstract setting, it is unclear how relevant they are in an experimental context, where control is typically limited. Here we address this question by showing that optimal work extraction is possible for a realistic engine. The latter consists of a superconducting circuit, where a LC-resonator is coupled to a Josephson junction. The oscillator state fuels the engine, providing energy absorbed by Cooper pairs, thus producing work in the form of an electrical current against an external voltage bias. We show that this machine can extract the maximal amount of work from all Gaussian and Fock states. Furthermore, we consider work extraction from a continuously stabilized oscillator state. In both scenarios, coherence between energy eigenstates is beneficial, increasing the power output of the machine. This is possible because the phase difference across the Josephson junction provides a phase reference.Comment: Published versio

Population genetic structure of Mycosphaerella graminicola and Quinone Outside Inhibitor (QoI) resistance in the Czech Republic

Damage caused by the wheat pathogen Mycosphaerella graminicola increased rapidly during the last two decades in the Czech Republic. We collected isolates from naturally infected fields in seven wheat-growing locations and analysed these using eight microsatellite markers. All markers were highly polymorphic. We found a high degree of genetic diversity and low clonality within all sampled Czech populations. We identified 158 unique multilocus haplotypes among 184 isolates. Field populations showed weak genetic structure but we detected more differentiation between climatic regions within the Czech Republic. We compared the Czech field populations to populations from the United Kingdom, Germany and Switzerland and found a marked differentiation between Czech populations and Western European populations. We hypothesize that decades of different agricultural practices, including the use of different wheat cultivars, may explain this genetic differentiation. We detected a rapid increase in QoI fungicide resistance during the sampling period from 2005 to 2011, coinciding with the widespread application of this class of fungicides in the Czech Republic. M. graminicola populations in the Czech Republic underwent a rapid adaptive evolution from sensitivity to resistance similar to what was described earlier in Western Europ