On the structure of non-full-rank perfect codes

The Krotov combining construction of perfect 1-error-correcting binary codes from 2000 and a theorem of Heden saying that every non-full-rank perfect 1-error-correcting binary code can be constructed by this combining construction is generalized to the $q$-ary case. Simply, every non-full-rank perfect code $C$ is the union of a well-defined family of $\mu$-components $K_\mu$, where $\mu$ belongs to an "outer" perfect code $C^*$, and these components are at distance three from each other. Components from distinct codes can thus freely be combined to obtain new perfect codes. The Phelps general product construction of perfect binary code from 1984 is generalized to obtain $\mu$-components, and new lower bounds on the number of perfect 1-error-correcting $q$-ary codes are presented.Comment: 8 page

A smoothing monotonic convergent optimal control algorithm for NMR pulse sequence design

The past decade has demonstrated increasing interests in using optimal control based methods within coherent quantum controllable systems. The versatility of such methods has been demonstrated with particular elegance within nuclear magnetic resonance (NMR) where natural separation between coherent and dissipative spin dynamics processes has enabled coherent quantum control over long periods of time to shape the experiment to almost ideal adoption to the spin system and external manipulations. This has led to new design principles as well as powerful new experimental methods within magnetic resonance imaging, liquid-state and solid-state NMR spectroscopy. For this development to continue and expand, it is crucially important to constantly improve the underlying numerical algorithms to provide numerical solutions which are optimally compatible with implementation on current instrumentation and at same time are numerically stable and offer fast monotonic convergence towards the target. Addressing such aims, we here present a smoothing monotonically convergent algorithm for pulse sequence design in magnetic resonance which with improved optimization stability lead to smooth pulse sequence easier to implement experimentally and potentially understand within the analytical framework of modern NMR spectroscopy

Effective low-energy theory for correlated carbon nanotubes

The low-energy theory for single-wall carbon nanotubes including Coulomb interactions is derived and analyzed. It describes two fermion chains without interchain hopping but coupled in a specific way by the interaction. The strong-coupling properties are studied by bosonization, and consequences for experiments on single armchair nanotubes are discussed.Comment: 5 pages REVTeX, includes one figur

High Fidelity Quantum Gates in the Presence of Dispersion

We numerically demonstrate the control of motional degrees of freedom of an ensemble of neutral atoms in an optical lattice with a shallow trapping potential. Taking into account the range of quasimomenta across different Brillouin zones results in an ensemble whose members effectively have inhomogeneous control fields as well as spectrally distinct control Hamiltonians. We present an ensemble-averaged optimal control technique that yields high fidelity control pulses, irrespective of quasimomentum, with average fidelities above 98%. The resulting controls show a broadband spectrum with gate times in the order of several free oscillations to optimize gates with up to 13.2% dispersion in the energies from the band structure. This can be seen as a model system for the prospects of robust quantum control. This result explores the limits of discretizing a continuous ensemble for control theory

Low Energy Properties of the (n,n) Carbon Nanotubes

According to band theory, an ideal undoped (n,n) carbon nanotube is metallic. We show that the electron-electron interaction causes it to become Mott insulating with a spin gap. More interestingly, upon doping it develops superconducting fluctuations.Comment: 5pages, 2eps figures, one reference added, final version, accepted to PR

Colloquium: Trapped ions as quantum bits -- essential numerical tools

Trapped, laser-cooled atoms and ions are quantum systems which can be experimentally controlled with an as yet unmatched degree of precision. Due to the control of the motion and the internal degrees of freedom, these quantum systems can be adequately described by a well known Hamiltonian. In this colloquium, we present powerful numerical tools for the optimization of the external control of the motional and internal states of trapped neutral atoms, explicitly applied to the case of trapped laser-cooled ions in a segmented ion-trap. We then delve into solving inverse problems, when optimizing trapping potentials for ions. Our presentation is complemented by a quantum mechanical treatment of the wavepacket dynamics of a trapped ion. Efficient numerical solvers for both time-independent and time-dependent problems are provided. Shaping the motional wavefunctions and optimizing a quantum gate is realized by the application of quantum optimal control techniques. The numerical methods presented can also be used to gain an intuitive understanding of quantum experiments with trapped ions by performing virtual simulated experiments on a personal computer. Code and executables are supplied as supplementary online material (http://kilian-singer.de/ent).Comment: accepted for publication in Review of Modern Physics 201

В поисках Атлантиды: предиктивные биомаркеры ответа на иммунотерапию

The emergence and continuous development of immune checkpoint inhibitors (ICIs) therapy brings a revolution in cancer therapy history including urothelial carcinoma. Early accurate targeting and adequate treatment are critical to patient prognosis and overall survival. To overcome these limitations, two strategies are actively being pursued: identification of predictive biomarkers for clinical response to ICIs and multi-pronged combination therapies. Biomarkers might allow clinicians to practice a precision medicine approach in ICIs (biomarkerbased patient selection). The development of predictive biomarkers is needed to optimize patient benefit, minimize risk of toxicities, and guide combination approaches.The greatest focus in clinical trials and reviews has been on tumor-cell PD-L1 expression. Although PD-L1 positivity enriches for populations with clinical benefit, PD-L1 testing alone is insufficient for patient selection in most malignancies. In this review, we discuss the status of PD-L1 testing and explore emerging data on new biomarker strategies with tumor-infiltrating lymphocytes, mutational burden, immune gene signatures, microsatellite instability and molecular subtypes.Появление и постоянное развитие терапии с использованием ингибиторов иммунных контрольных точек (ICI) совершили революцию в истории лечения рака, в том числе уротелиальной карциномы. Ранний точный подбор мишени и адекватное лечение имеют решающее значение для прогноза заболевания и продолжительности общей выживаемости. Для преодоления этих ограничений активно используются 2 стратегии: идентификация прогностических биомаркеров для клинического ответа при ICI-терапии и пролонгированная комбинированная терапия. Биомаркеры могут позволить клиницистам практиковать подходы прецизионной медицины при назначении ICI-терапии (отбор пациентов на основе биомаркеров).Наибольшее внимание в клинических испытаниях и обзорах уделяется экспрессии PD-L1 в опухолевых клетках. Несмотря на то что случаи уротелиального рака с положительной экспрессией PD-L1 могут иметь потенциальную выгоду при назначении иммунотерапии, одного тестирования PD-L1 недостаточно для отбора пациентов при большинстве злокачественных новообразований. В данном обзоре мы обсуждаем статус тестирования PD-L1 и представляем новые данные о потенциальных предиктивных биомаркерах при назначении ICI-терапии: факторы противоопухолевого иммунитета, мутационную нагрузку и сигнатуры генов, микросателлитную нестабильность и молекулярные подтипы рака мочевого пузыря

Supersymmetry in carbon nanotubes in a transverse magnetic field

Electron properties of Carbon nanotubes in a transverse magnetic field are studied using a model of a massless Dirac particle on a cylinder. The problem possesses supersymmetry which protects low energy states and ensures stability of the metallic behavior in arbitrarily large fields. In metallic tubes we find suppression of the Fermi velocity at half-filling and enhancement of the density of states. In semiconducting tubes the energy gap is suppressed. These features qualitatively persist (although to a smaller degree) in the presence of electron interactions. The possibilities of experimental observation of these effects are discussed.Comment: A new section on electron interaction effects added and explanation on roles of supersymmetry expanded. Revtex4, 6 EPS figure file

Quantum spin field effect transistor

We propose, theoretically, a new type of quantum field effect transistor that operates purely on the flow of spin current in the absence of charge current. This spin field effect transistor (SFET) is constructed without any magnetic material, but with the help of spin flip mechanism provided by a rotating external magnetic field of uniform strength. The SFET generates a constant instantaneous spin current that is sensitively controllable by a gate voltage as well as by the frequency and strength of the rotating field. The characteristics of a Carbon nanotube based SFET is provided as an example

ДЕСМОИДНАЯ ОПУХОЛЬ СРЕДОСТЕНИЯ: 6-ЛЕТНЕЕ КЛИНИЧЕСКОЕ НАБЛЮДЕНИЕ ПОСЛЕ КОМБИНИРОВАННОГО ЛЕЧЕНИЯ (СЛУЧАЙ ИЗ ПРАКТИКИ)

Extra-abdominal desmoids are tumors with borderline biologic behavior and tendency to frequent local recurrence. The paper presents a case of successful treatment of this rare tumor with involvement of mediastinal structures. The combined modality treatment resulted in 6-year disease-free survival.Экстраабдоминальный десмоид – новообразование с пограничной биологической природой и склонностью к частому местному рецидивированию. Представлен случай успешного лечения редкой локализации этой опухоли с поражением структур средостения. Длительный безрецидивный период (в течение 6 лет) после лечения обусловлен применением методов комбинированного лечения.