The Bose-Hubbard model with localized particle losses

We consider the Bose-Hubbard model with particle losses at one lattice site. For the non-interacting case, we find that half of the bosons of an initially homogeneous particle distribution, are not affected by dissipation that only acts on one lattice site in the center of the lattice. A physical interpretation of this result is that the surviving particles interfere destructively when they tunnel to the location of the dissipative defect and therefore never reach it. Furthermore we find for a one-dimensional model that a fraction of the particles can propagate across the dissipative defect even if the rate of tunneling between adjacent lattice sites is much slower than the loss rate at the defect. In the interacting case, the phase coherence is destroyed and all particles eventually decay. We thus analyze the effect of small interactions and small deviations from the perfectly symmetric setting on the protection of the particles against the localized losses. A possible experimental realization of our setup is provided by ultracold bosonic atoms in an optical lattice, where an electron beam on a single lattice site ionizes atoms that are then extracted by an electrostatic field.Comment: 10 pages, 5 figures, minor revisions to previous versio

Infrared molecular fingerprinting of blood-based liquid biopsies for the detection of cancer

Recent omics analyses of human biofluids provide opportunities to probe selected species of biomolecules for disease diagnostics. Fourier-transform infrared (FTIR) spectroscopy investigates the full repertoire of molecular species within a sample at once. Here, we present a multi-institutional study in which we analysed infrared fingerprints of plasma and serum samples from 1639 individuals with different solid tumours and carefully matched symptomatic and non-symptomatic reference individuals. Focusing on breast, bladder, prostate, and lung cancer, we find that infrared molecular fingerprinting is capable of detecting cancer: training a support vector machine algorithm allowed us to obtain binary classification performance in the range of 0.78-0.89 (area under the receiver operating characteristic curve [AUC]), with a clear correlation between AUC and tumour load. Intriguingly, we find that the spectral signatures differ between different cancer types. This study lays the foundation for high-throughput onco-IR-phenotyping of four common cancers, providing a cost-effective, complementary analytical tool for disease recognition

Defekt-Phononen-Wechselwirkungen in Diamant Nanostrukturen

Zusammenfassung in deutscher SpracheAbweichender Titel nach Übersetzung der Verfasserin/des VerfassersIn dieser Doktorarbeit werden neue Methoden zur Ku¿hlung und Anregung von mechanischen Schwingungen in Diamant-Nanoresonatoren theoretisch analysiert. Die untersuchten Techniken zur Kontrolle der mechanischen Moden basieren dabei zum ersten Mal auf der intrinsischen Deformationskopplung der Schwingungen an natu¿rliche Stickstoff- und Siliziumstörstellen in Diamant. Ausgehend von einer mikroskopischen Modellierung solcher Kopplungen werden in dieser Arbeit verschiedene theoretische Methoden aus dem Bereich der Quantenoptik verwendet, um das Laserku¿hlen von mechanischen Resonatoren bis Nahe an den quantenmechanischen Grundzustand, als auch die Realisierung von sogenannten Phononenlaser zu beschreiben. Dabei wird vor allem gezeigt, wie quasi-entartete Energiezustände dieser Defektzentren ausgenu¿tzt werden können, um diese Effekte zu optimieren und dadurch auch unter experimentell relevanten Bedingungen möglich zu machen. Daru¿ber hinaus wird in dieser Doktorarbeit untersucht, wie Phononen-induzierte Dissipation gezielt dazu verwendet werden kann, um anderen mechanische Schwingungsmoden zu ku¿hlen oder auch in einen stationären verschränkten Zustand zu pumpen. Als eine interessante Erweiterung der oben beschriebenen Effekte werden im dritten Teil dieser Doktorarbeit Systeme mit zwei oder mehreren gekoppelten Resonatoren behandelt, wobei die mechanischen Moden abwechselnd geku¿hlt oder mit der selben Rate gepumpt werden. Im klassischen Grenzfall besitzt die Dynamik solcher Systeme eine sogenannte Paritäts-Zeitumkehr-Symmetrie, welche fu¿r bestimmte Systemparameter gebrochen wird. In dieser Arbeit werden zum ersten Mal die Konsequenzen dieser Symmetriebrechung fu¿r die stationären Zustände dieser Systeme unter realistischen Bedingungen beschrieben. Dabei zeigt sich, dass die Kombination von nichtlinearen Sättigungseffekten und der Einfluss von thermischen als auch Quantenrauschen zu unerwarteten Ergebnissen fu¿hrt, die sich deutlich von der dynamischen Symmetriebrechung unterscheiden. Insbesondere findet man weitere Phasen mit teilweise erhaltener oder gebrochener Paritäts-Zeitumkehr-Symmetrie, sowie einem Übergang von einem thermischen Zustand in eine Lasing-Phase mit stark reduzierten Fluktuationen.This doctoral thesis investigates potential phonon-cooling and phonon-lasing schemes as well as quantum applications with diamond nano-mechanical resonators also known as phonon cavities. These particular schemes are for the first time based on the exploitation of the multi-level energy structure of diamond's natural defects such as nitrogen-vacancy and silicon-vacancy centers. We develop microscopic models for defect-phonon interactions and use various quantum optical methods to explore different laser manipulation schemes under realistic experimental conditions. In particular, we investigate the strain-induced coupling between a nitrogen-vacancy impurity and resonant vibrational modes of diamond nano-mechanical resonators. This coupling can modify the state of the resonator and either cool a vibrational mode close to the quantum ground state or excite it into a large-amplitude coherent state, a phenomenon known as phonon lasing. In addition, we study a setup where a silicon-vacancy center is magnetically coupled to a low-frequency mechanical bending mode and via strain to the continuum of high-frequency longitudinal modes of a singly-clamped diamond beam. This setup can be used to induce cooling effects for the low-frequency mechanical vibrations, where the high-frequency longitudinal compression modes of the beam serve as an intrinsic low-temperature reservoir. A natural extension of the above-described setups is a system of two-coupled resonators. Assuming that one of the oscillators is cooled and the other is heated with the same rate, such a gain-loss system offers an ideal setup for investigating the physics of so-called parity-time-symmetric systems, under realistic conditions. Specifically, we present a new type of parity-time-symmetry breaking, which occurs in the steady-state energy distribution of classical (and open quantum) systems with balanced gain and loss. We show that the combination of non-linear saturation effects and the presence of thermal or quantum noise in actual experiments results in unexpected behavior that differs significantly from the usual dynamical picture. We observe additional phases with preserved or broken parity-time symmetry as well as a transition from a very noisy thermal state to a low-energy lasing state with strongly reduced fluctuations.12

Stability of person-specific blood-based infrared molecular fingerprints opens up prospects for health monitoring

Health state transitions are reflected in characteristic changes in the molecular composition of biofluids. Detecting these changes in parallel, across a broad spectrum of molecular species, could contribute to the detection of abnormal physiologies. Fingerprinting of biofluids by infrared vibrational spectroscopy offers that capacity. Whether its potential for health monitoring can indeed be exploited critically depends on how stable infrared molecular fingerprints (IMFs) of individuals prove to be over time. Here we report a proof-of-concept study that addresses this question. Using Fourier-transform infrared spectroscopy, we have fingerprinted blood serum and plasma samples from 31 healthy, non-symptomatic individuals, who were sampled up to 13 times over a period of 7 weeks and again after 6 months. The measurements were performed directly on liquid serum and plasma samples, yielding a time- and cost-effective workflow and a high degree of reproducibility. The resulting IMFs were found to be highly stable over clinically relevant time scales. Single measurements yielded a multiplicity of person-specific spectral markers, allowing individual molecular phenotypes to be detected and followed over time. This previously unknown temporal stability of individual biochemical fingerprints forms the basis for future applications of blood-based infrared spectral fingerprinting as a multiomics-based mode of health monitoring

Limits and Prospects of Molecular Fingerprinting for Phenotyping Biological Systems Revealed through <i>In Silico</i> Modeling

Molecular fingerprinting via vibrational spectroscopy characterizes the chemical composition of molecularly complex media which enables the classification of phenotypes associated with biological systems. However, the interplay between factors such as biological variability, measurement noise, chemical complexity, and cohort size makes it challenging to investigate their impact on how the classification performs. Considering these factors, we developed an in silico model which generates realistic, but configurable, molecular fingerprints. Using experimental blood-based infrared spectra from two cancer-detection applications, we validated the model and subsequently adjusted model parameters to simulate diverse experimental settings, thereby yielding insights into the framework of molecular fingerprinting. Intriguingly, the model revealed substantial improvements in classifying clinically relevant phenotypes when the biological variability was reduced from a between-person to a within-person level and when the chemical complexity of the spectra was reduced. These findings quantitively demonstrate the potential benefits of personalized molecular fingerprinting and biochemical fractionation for applications in health diagnostics

Limits and Prospects of Molecular Fingerprinting for Phenotyping Biological Systems Revealed through <i>In Silico</i> Modeling

Molecular fingerprinting via vibrational spectroscopy characterizes the chemical composition of molecularly complex media which enables the classification of phenotypes associated with biological systems. However, the interplay between factors such as biological variability, measurement noise, chemical complexity, and cohort size makes it challenging to investigate their impact on how the classification performs. Considering these factors, we developed an in silico model which generates realistic, but configurable, molecular fingerprints. Using experimental blood-based infrared spectra from two cancer-detection applications, we validated the model and subsequently adjusted model parameters to simulate diverse experimental settings, thereby yielding insights into the framework of molecular fingerprinting. Intriguingly, the model revealed substantial improvements in classifying clinically relevant phenotypes when the biological variability was reduced from a between-person to a within-person level and when the chemical complexity of the spectra was reduced. These findings quantitively demonstrate the potential benefits of personalized molecular fingerprinting and biochemical fractionation for applications in health diagnostics