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John Quincy Adams
No full textAdvertisement for Ballard's Liver Pills, a remedy prepared by B.M. Butler & Co., Chicago
Plummer's Essence of Jamaica Ginger
No full textTrade card advertising Plummer's Essence of Jamaica Ginger, a remedy prepared by B.M. Butler & Co., Chicago. The recto of the card is oriented horizontally; the verso vertically. Part of the upper left corner is missing from this card. Title on verso: Plummer's Essence of Jamaica Ginger
Optimizing quantum error correction for superconducting qubit processors
No full textThe theory of quantum mechanics describes many phenomena that may initially seem to be counter-intuitive and, in some cases, impossible, given the understanding of classical mechanics that most of us are more intimately familiar with. Following its initial introduction, there was a great deal of debate among scientists regarding the predictions made by this theory. The strange nature of quantum mechanics has led to many memorable quotes and the use of “spooky” to describe some of these predictions. Since its initial introduction, quantum mechanics has been rigorously tested and has proven to be quite a successful theory. Quantum mechanics has found many different applications and has led to the existence of devices and technologies we use daily. Another potential application of quantum mechanics is quantum computation, which Richard Feynman first put forward as an idea in 1982. Quantum computers have the potential to solve specific problems that can be infeasible for even the most powerful (classical) supercomputers and have potential applications in many different areas, such as quantum chemistry, cryptography, and optimization. However, performing a quantum computation is challenging and requires overcoming the inherent fragility of quantum systems. Storing information in a quantum system requires it to be well isolated from the environment to avoid any unwanted interactions that can corrupt the stored data. Unfortunately, at the same time, we need the ability to control this system, make it interact with other such systems, and ultimately measure it for us to perform an actual computation. This is a universal issue and all of the systems we have so far developed to be used as quantum bits (qubits) have been plagued by noise. Each operation applied to the qubit or even the act of leaving the qubit idling for some time generally leads to an error with a non-negligible probability. The impact of this noise has so far prevented quantum computers from performing any practical computation. While substantial efforts have been made to reduce these physical error rates over the past several years, we are still far from the universal fault-tolerant quantum computers we ultimately strive for. Fortunately, quantum error correction can help us reach the low error rates necessary for quantum computers to realize their potential applications in the future. This can be achieved by storing the quantum information in a logical qubit instead of a noisy physical one. When using a stabilizer code, which will be the focus of this dissertation, this logical information is distributed over many (noisy) physical qubits, referred to as data qubits. Another set of qubits, the so-called ancilla qubits, is used to perform indirect parity measurements, which do not destroy the stored information but give some information about whether an error has occurred. We then try to interpret this information to identify what errors have happened and correct them, which is done by a classical algorithm referred to as the decoder. Increasing the number of physical qubits used to encode the logical qubits allows more physical errors to be detected and corrected. The number of correctable errors is captured by the distance of the code, defined as the minimum number of physical single-qubit errors that constitute a logical error. One of the critical properties of error correction is the ability to reduce the logical error rate by increasing the code distance, which requires the physical error rates to be below some threshold value. The valiant experimental effort over the years has led to several recent experiments that implement various error-correcting codes and demonstrate the reduction of the error rates promised by error correction. In particular, these experiments (and the experiments leading up to them) identified several noise sources that had not been explored in sufficient detail and could significantly impact the logical performance of the code. In this dissertation, we explore the impact of the noise encountered in transmon-qubit devices on the performance of error-correcting codes, namely the surface code. Transmon qubits are, in practice, multi-level systems, and only the lowest two energy levels are used for computation. Unfortunately, they are also weakly anharmonic, leading to the applied operations having some probability of exciting the qubit outside of this computational subspace, referred to as a leakage error. We explore the impact of leakage in both simulations and experiments and develop schemes to mitigate it. We also consider other approaches to improve the logical performance or to reduce unwanted interactions. In Chapter 2, we develop a realistic model of leakage induced by the two-qubit gates between flux-tunable transmon qubits. We show that leaked qubits effectively spread errors on their neighboring qubits, which are then detected by the parity measurements. We show that a Hidden Markov model can detect the increased error rate due to leakage. This enables us to post-select out runs during which any qubit has leaked to restore the code performance. Unfortunately, post-selection is ultimately not scalable. Instead, it is desirable to have operations that return leaked qubits to the computational subspace. These operations are called leakage-reduction units and convert leakage into a regular error. In Chapter 3, we propose a leakage-reduction scheme, which does not require any overhead in the time needed to perform the parity measurements or an overhead in the quantum hardware. For data qubits, we propose an operation that transfers the leakage to a dedicated readout resonator, where it can quickly decay. This operation is designed to not disturb the computational states, allowing it to be applied unconditionally. For the ancilla qubit, we use the fact that measurements can determine if a qubit is in the leaked state. We then apply a conditional operation to return the qubit to the computational subspace whenever it is measured to be leaked. Using detailed density-matrix simulation, we show that this scheme can be easily implemented to remove qubit leakage from the system, mitigating its impact on the logical performance of the code. In Chapter 4, we realize the data-qubit leakage reduction unit in an experiment and show it can also be used to remove ancilla-qubit leakage, removing the need for fast conditional operations and readout that distinguishes the leaked states. We show that these operations can remove most of the leaked population in about a hundred nanoseconds while having a negligible impact on the computational subspace. We also demonstrate that these operations decrease the number of observed errors by a two-qubit parity check, showing that the effect of leakage can be mitigated. Chapter 5 considers an architecture employing two types of superconducting qubits, the transmon qubit and the fluxonium qubit. These qubits have very different frequencies, making it unclear whether these qubits can even interact with each other in the first place. We show that the interactions with the higher-excited states can be utilized to perform operations between them, and we propose two types of gates. In practice, qubit frequencies are targeted with only a certain precision in fabrication. In certain cases, this can lead to unwanted interaction between qubits that increase the physical error rates, referred to as frequency collisions. We show that the large detuning between these qubits reduces the frequency of frequency collision, thereby increasing the expected fabrication yield. In Chapter 6, we realize a distance-two surface code experiment and perform repeated parity measurements to detect and post-select errors, given that it’s impossible to correct them when using such a small code. We implement a suite of logical operations for this code, including initialization, measurement, and several single-qubit gates. In the context of error detection, a logical operation is said to be fault-tolerant if the errors produced by each operation are detectable. We show that fault-tolerant variants of operations perform better than non-fault-tolerant ones. We also characterize the impact of various noise sources on the code performance. In Chapter 7, we look at another small-distance code, in this case, the distance-seven repetition code. We show that increasing the distance weakly suppresses the logical error rate of the code. We investigate the limiting factors behind the observed logical performance by analyzing the correlation between the observed parity measurements and performing simulations using noise models parameterized by the measured physical error rates. Chapter 8 considers a decoder that can perform the error inference more accurately. In particular, we implement a neural network decoder and investigate how it performs on experimental data from surface code experiments. We show that the accuracy of this decoder approaches what can be achieved by an optimal and computationally inefficient tensor network decoder. Transmon measurement produces analog outcomes. These are then typically converted to binary ones, leading to some information loss. We show how a neural network can also use this analog information to improve the achieved logical performance further. We have investigated the impact of non-conventional errors in simulation and in several experiments, demonstrating the importance of characterizing and mitigating these errors. We expect the methods introduced in this dissertation to lead to lower logical error rates. In the short term, this can aid in demonstrations of the usefulness of error correction. In the long term, addressing such errors is important to ensure the ability to suppress logical error rates to sufficiently low levels. We finish this dissertation with a brief conclusion of each chapter. We also outline several potential challenges that can impact future error-correction experiments, namely how to reduce the larger qubit overhead needed for fault-tolerant computation and several error sources that might become a limiting factor for future error-correction experiments.QCD/Terhal Grou
Chlororithra fea Butler 1889
No full textChlororithra fea Butler, 1889 Figs. 1–5 Chlororithra fea Butler, 1889, Illust. typical Specimens Lepid. Heterocera Colln Br. Mus. 7: 22, 106, pl. 136, fig. 9. Lectotype male (BMNH), [India]: Kangra district, Dharmsala. Here designated. Geometra fea: Hampson, 1895, Fauna Br. India (Moths) 3: 497. Redescription Head: Antennae in male bipectinate to threefouths, ciliate apically; with shaft pale brown and pectinations dark brown. Frons dull yellow, middle width about 3 / 5 horizontal diameter of compound eye. Vertex pale brown. Labial palpus with all the segments whitish on both outer and inner surfaces; segment I and II roughscaled, segment III smooth and elongate in female compared to male, exposed. Tegula whitish intermixed with yellow green. Thorax: Dorsum whitish intermixed with pale yellow green; venter white. Length of forewing (base to apex) 16–17 mm in both male and female. Lines white, edged with darkgreen line or patch, which forming patches on costa. Subbasal line wavy; antemedial line wavy, edged with darkgreen outward; postmedial line serrated, edged with darkgreen inward; antemedial and postmedial lines approaching to each other towards inner margin; submarginal line fairly wavy, extending inwards along veins, connected with postmedial line and forming oval patches between these two lines, accompanying darkgreen patch on both sides; terminal line forming white, round patch between veins. Discal spot darkgreen, slender and bent, extending to costa. Fringe white between veins and greygreen on veins. Hindwing with streaks quite similar to forewing. Usually with darkgreen patch near apex much darker, looks like blackbrown patch (when blackbrown patch on underside discernable). Underside: whitish, pale to dark, hindwing much paler than forewing; streaks on upperside visible; generally the row of patches between postmedial and submarginal lines much stronger on forewing. Usually apex of hindwing with distinct blackbrown patch (while this patch on upperside also discernable, but a little weaker) except for the specimens from Burma. Abdomen: Dorsum and upper lateral side yellowgreen with white intersegment; venter and lower lateral side whitish. Male genitalia (Figs. 9–13) with uncus long and narrow, rodlike, usually bent, sclerotized. Socii similar in length and shape to uncus, setose, slightly to moderately broader than uncus. Gnathos with slender, rodlike median process bearing a short pointed tooth subapically. Valva with costal lobe broad, well sclerotized, expanded subapically, and with apex rounded to pointed, spinose, extending from remainder of valva, bearing a fingerlike, spinulose, sclerotized process near base. Sacculus sclerotized, unmodified. Transtilla a pair of membranous processes. Juxta sclerotized, arcliked. Anellus a pair of sclerotized slender processes extending posteriorly, connected to gnathos by membrane. Saccus not protruding. Coremata present, weakly to strongly developed. Aedeagus long and narrow, with posterior half well sclerotized and spinulate; cornuti absent. Sternite 3 of abdomen with a pair of setal patches. Segment 8 (Fig. 21) modified, sternite narrow, deeply depressed, with its inner margin smooth and curved, posterior margin with lateral sides blunt and spinulose; tergite much broader than sternite, almost roundly depressed, lateral blunt process sclerotized. Female genitalia (Fig. 14) with apophyses posteriores about 4 times of apophyses anteriores in length. Sternite 7 partly sclerotized, with a pair of lateral sclerotized processes posteriorally, process triangular and pointed. Ostium slightly sclerotized. Ductus bursae long, more narrow anteriorally, about one and a half times of corpus bursae in length. Corpus bursae oval, membranous; signum absent. Biology Larvae feed on Quercus alba and have a resting posture that is similar to a flower of the tree (Prout, 1935). Adults are active from April to September. According to label data, the species ranges from 1800–2600 m above mean sea level. Material examined BHUTAN: PankasariHill, Brit. Buthan, 9 / 57, ex coll. R. Oberthür, 1 female (ZFMK). BURMA: Mt. Victoria, Pakokku Chin Hills, 2600 m. 2–31.v. 1938 (G. Heinrich), Brit.Mus. 1938 689, 3 males (BMNH); W. Myanmar, Chin State Ca. 1.5 km, W. Hakha, 22 ° 38 ’N, 93 ° 36 ’E, 2260 m, 23–24.v. 2001, leg. S. Naumann, 1 male (ZFMK). CHINA: Gansu Diebuanzigou, 2005. VII. 12, 2100 m, 1 female (IZCAS); Sichuan Dukou, 1981. VI. 4, leg. Zhang Baolin, 1 male (IZCAS); Xizang Zhangmukoan, 1981. VI. 6 (abdomen missing), 1 male (IZCAS); Tsekou, P. Dubernard, 1898, Ex. Oberthür Coll. Brit. Mus. 1927 3 (one labeled: Chlororithra fea Butler var. missioniaria Oberthür) (originally as syntypes of missioniaria), 2 males (BMNH), 1900 (originally as syntype of missioniaria), 1 male (BMNH); Chine [China], Yunnan, Tsetchong, Près, Weisi, R.P. Ouvrard, Ex. Oberthür Coll. Brit. Mus. 1927 3, 1 male (BMNH); Tsékou, 1900, R.P. J. Dubernard (other labels: yellow label: missionaria Obthr. Type, abgebildet Seitz IV. Suppl. fig.; Chlororithra fea Butler, var. missioniaria Obthr. male) (originally as syntype of missioniaria), 1 male (ZFMK); [Yunnan], Tsekou, 1900, R.P. Dubernard (originally as syntype of missioniaria), 1 male (ZFMK), R.P. Dubernard, 1895 (originally as syntypes of missioniaria), 2 males (ZFMK); Westchina, 9 / 57, excoll. R. Oberthür, 1 male (ZFMK). INDIA: Kangra district, Dharmsala, lectotype male (BMNH), 87.59 (664), larva on Quercus alba (other labels: Pseudasthena fea Butler, male, type; red type label), 1 male (BMNH); paralectotype, ibidem (other labels: Pseudasthena fea Butler, female, type; red type label), 1 female (BMNH); paralectotypes?, ibidem (other label: Pseudasthena fea Butler), 2 males (BMNH); Khasis, Sept. 1896, Nat. Coll, Rothschild Bequest, B.M. 1939 1, 1 male (BMNH), April 1897, Nat. Coll. Rothschild Bequest, B.M. 1939 1, 1 male (BMNH); Inde Anglaise Pedong, Région de Darjeeling, Chasseurs indigènes, 1934, 1 female (ZFMK); Inde Anglaise Pedong, District de Darjeeling, Chasseurs indigènes, 1931, 1 female (ZFMK); Khasis, Nat. Coll., Davidson Coll. B.M. 1925 574, 1 male (ZFMK). NEPAL: Kathmandu Valley, Godavari, Phulchoki, 2150 m, 10.5. 1989, leg. Schnitzler, Museum A. Koenig Eing. Nr. 89 / 244, 1 male (ZFMK). PAKISTAN: Murree, 92–98, Harford, Coll. 1887, 1 male, 1 female (BMNH); ibidem, 1900, 1 female (BMNH); Kashmir Himalays Mts., 30 km N. Murree, near Nathia Ghali Ayubia Vill, 2600 m, 20.vi. 2000, leg. Varga & Ronkay, 1 male (ZFMK). SIKKIM: Gopaldhara, Mirik (H. Stevens), Rothschild Bequest, B.M. 1939 1, 1 male, 1 female (BMNH); Indien Sikkim, Peneryangtao, 2000 m, 20–27.viii. 1988, leg. W. Thoman, Museum A. Koenig Eing. Nr. 90 / 263, 1 female (ZFMK); Indien Sikkim, vic Pelling, 1800 m, 27.VIII. 1988, leg. W. Thomas, Museum A. Koenig Eing. Nr. 90 / 263, 1 male (ZFMK). Remarks A lectotype is designated in order to provide nomenclatural stability to this taxon. The hindwing of this species usually bears a blackbrown patch on the underside that is discernable on the upperside, except in specimens from Burma (Fig. 3) (in one specimen the patch is visible only on the underside and in another it is absent on both sides). In specimens from Burma, the apex of the valva in the male genitalia is rounded and the coremata are very weak; in specimens from Dharmsala (Fig. 10), Sikkim (Fig. 11), and Tsetchong (Yunnan, China) (Fig. 12) the apex is much more pointed and coremata are well developed. In specimens from Dharmsala and Tsetchong the costal basal process is much broader than in specimens from elsewhere. Owing to subtle differences in the genitalia, specimens from Burma may represent a distinct species; however, the examination of more material, especially females, is necessary before such a conclusion can be drawn.Published as part of Hongxiang, Han, Hongmei, Li, Dayong & Xue, 2006, Revision of Chlororithra Butler, 1889 (Lepidoptera, Geometridae, Geometrinae), pp. 29-39 in Zootaxa 1221 on pages 31-36, DOI: 10.5281/zenodo.17257
Monitoring biodegradation capacity of organic pollutants in the environment
No full textMicro-organismen zijn in staat om organische verbindingen om te zetten in minder schadelijke stoffen en spelen daarom een belangrijke rol bij het opruimen van milieuvervuiling. Voor beleidsmakers, landgebruikers en landeigenaren is het belangrijk dat er bij milieuverontreiniging goed toezicht wordt gehouden op de biologische afbraakprocessen en dat deze goed worden beheerst. Aangezien microbiële activiteit in het milieu wordt beïnvloed door diverse fysische, geochemische en biologische factoren, is nauwkeurige kennis van het afbraakproces hierbij noodzakelijk. In dit promotieonderzoek wordt de relatie tussen geochemische condities en de biologische afbraakcapaciteit van micro-organismen in het milieu beschreven, inclusief methoden om de activiteit en metabole functies van deze micro-organismen in het milieu te mete
Building Simplification using Offset Curves obtained from the Straight Skeleton
No full textWe propose a conceptual simple algorithm based on offset curves obtained from the straight skeleton to simplify building outlines. We present initial results with some real world data and show that the approach can be used to simplify and amalgamate building outlines. We discuss how this approach can be extended to generate smooth transitions for continuous zoom.Accepted Author ManuscriptOLD Department of GIS Technolog
Optical measuring techniques for particulate systems at the fringes of concentration - paints and aerosols
No full textApplied Science
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