Realizing a deep reinforcement learning agent for real-time quantum feedback.

Realizing the full potential of quantum technologies requires precise real-time control on time scales much shorter than the coherence time. Model-free reinforcement learning promises to discover efficient feedback strategies from scratch without relying on a description of the quantum system. However, developing and training a reinforcement learning agent able to operate in real-time using feedback has been an open challenge.

TMM-Fast, a transfer matrix computation package for multilayer thin-film optimization: tutorial.

Achieving the desired optical response from a multilayer thin-film structure over a broad range of wavelengths and angles of incidence can be challenging. An advanced thin-film structure can consist of multiple materials with different thicknesses and numerous layers. Design and optimization of complex thin-film structures with multiple variables is a computationally heavy problem that is still under active research.

Topological phonon transport in an optomechanical system.

Light is a powerful tool for controlling mechanical motion, as shown by numerous applications in the field of cavity optomechanics. Recently, small scale optomechanical circuits, connecting a few optical and mechanical modes, have been demonstrated in an ongoing push towards multi-mode on-chip optomechanical systems. An ambitious goal driving this trend is to produce topologically protected phonon transport.

Observing polarization patterns in the collective motion of nanomechanical arrays.

In recent years, nanomechanics has evolved into a mature field, and it has now reached a stage which enables the fabrication and study of ever more elaborate devices. This has led to the emergence of arrays of coupled nanomechanical resonators as a promising field of research serving as model systems to study collective dynamical phenomena such as synchronization or topological transport. From a general point of view, the arrays investigated so far can be effectively treated as scalar fields on a lattice.

Arbitrary optical wave evolution with Fourier transforms and phase masks.

A large number of applications in classical and quantum photonics require the capability of implementing arbitrary linear unitary transformations on a set of optical modes. In a seminal work by Reck et al. [Phys.

Renormalized Mutual Information for Artificial Scientific Discovery.

We derive a well-defined renormalized version of mutual information that allows us to estimate the dependence between continuous random variables in the important case when one is deterministically dependent on the other. This is the situation relevant for feature extraction, where the goal is to produce a low-dimensional effective description of a high-dimensional system. Our approach enables the discovery of collective variables in physical systems, thus adding to the toolbox of artificial scientific discovery, while also aiding the analysis of information flow in artificial neural networks.

Many-Body Dephasing in a Trapped-Ion Quantum Simulator.

How a closed interacting quantum many-body system relaxes and dephases as a function of time is a fundamental question in thermodynamic and statistical physics. In this Letter, we analyze and observe the persistent temporal fluctuations after a quantum quench of a tunable long-range interacting transverse-field Ising Hamiltonian realized with a trapped-ion quantum simulator. We measure the temporal fluctuations in the average magnetization of a finite-size system of spin-1/2 particles.

Quantum nondemolition measurement of mechanical motion quanta.

The fields of optomechanics and electromechanics have facilitated numerous advances in the areas of precision measurement and sensing, ultimately driving the studies of mechanical systems into the quantum regime. To date, however, the quantization of the mechanical motion and the associated quantum jumps between phonon states remains elusive. For optomechanical systems, the coupling to the environment was shown to make the detection of the mechanical mode occupation difficult, typically requiring the single-photon strong-coupling regime.

Light-induced cross-linking and post-cross-linking modification of polyglycidol.

The photoinduced radical generation process has received renewed interest due to its economic and ecological appeal. Herein the light-induced cross-linking of functional polyglycidol and its post-cross-linking modification are presented. Linear polyglycidol was first functionalized with a tertiary amine in a two-step reaction.

Novel Antibacterial Polyglycidols: Relationship between Structure and Properties.

Antimicrobial polymers are an attractive alternative to low molecular weight biocides, because they are non-volatile, chemically stable, and can be used as non-releasing additives. Polymers with pendant quaternary ammonium groups and hydrophobic chains exhibit antimicrobial properties due to the electrostatic interaction between polymer and cell wall, and the membrane disruptive capabilities of the hydrophobic moiety. Herein, the synthesis of cationic⁻hydrophobic polyglycidols with varying structures by post-polymerization modification is presented.

From Kardar-Parisi-Zhang scaling to explosive desynchronization in arrays of limit-cycle oscillators.

Phase oscillator lattices subject to noise are one of the most fundamental systems in nonequilibrium physics. We have discovered a dynamical transition which has a significant impact on the synchronization dynamics in such lattices, as it leads to an explosive increase of the phase diffusion rate by orders of magnitude. Our analysis is based on the widely applicable Kuramoto-Sakaguchi model, with local couplings between oscillators.

Acute kidney injury after abdominal aortic aneurysm repair: current epidemiology and potential prevention.

Purpose: Acute kidney injury (AKI) is a severe complication after infrarenal abdominal aortic aneurysm (iAAA) repair. Little data are available whether endovascular aneurysm (EVAR) or open aortic repair (OAR) differs with respect to AKI frequency and severity, consecutive development of chronic kidney disease (CKD) and potentially preventable and modifiable risk factors of AKI.

Patients And Methods: We assessed AKI rates, AKI stages and CKD applying current, complete definitions from the kidney disease improving global outcomes initiative in propensity-score-matched cohorts of all patients with elective and urgent iAAA repair at our institution from 2007 to 2011.

Permanent Decline of Renal Function after Infrarenal Abdominal Aortic Aneurysm Repair-Frequency and Risk Factors.

Background: Permanent renal function decline, and development and deterioration of chronic kidney disease (CKD) are associated with serious complications. How frequent is renal function decline after infrarenal abdominal aortic aneurysm (iAAA) repair according to current definitions and what are its risk factors, especially potentially modifiable ones?

Methods: Retrospective observational study including all patients with elective or urgent iAAA repair from 2007 to 2011. The primary outcome was renal function decline in the first year after iAAA repair, defined as permanent reduction of estimated glomerular filtration rate (eGFR) ≥20% from baseline and/or end-stage renal disease (ESRD), all in the first year after iAAA repair.

Many-Particle Dephasing after a Quench.

After a quench in a quantum many-body system, expectation values tend to relax towards long-time averages. However, temporal fluctuations remain in the long-time limit, and it is crucial to study the suppression of these fluctuations with increasing system size. The particularly important case of nonintegrable models has been addressed so far only by numerics and conjectures based on analytical bounds.

Pseudomagnetic fields for sound at the nanoscale.

There is a growing effort in creating chiral transport of sound waves. However, most approaches so far have been confined to the macroscopic scale. Here, we propose an approach suitable to the nanoscale that is based on pseudomagnetic fields.

Homoserine Lactone as a Structural Key Element for the Synthesis of Multifunctional Polymers.

The use of bio-based building blocks for polymer synthesis represents a milestone on the way to "green" materials. In this work, two synthetic strategies for the preparation of multifunctional polymers are presented in which the key element is the functionality of homoserine lactone. First, the synthesis of a bis cyclic coupler based on a thiolactone and homoserine lactone is displayed.

Quantum Nondemolition Measurement of a Quantum Squeezed State Beyond the 3 dB Limit.

We use a reservoir engineering technique based on two-tone driving to generate and stabilize a quantum squeezed state of a micron-scale mechanical oscillator in a microwave optomechanical system. Using an independent backaction-evading measurement to directly quantify the squeezing, we observe 4.7±0.

Topological phase transitions and chiral inelastic transport induced by the squeezing of light.

There is enormous interest in engineering topological photonic systems. Despite intense activity, most works on topological photonic states (and more generally bosonic states) amount in the end to replicating a well-known fermionic single-particle Hamiltonian. Here we show how the squeezing of light can lead to the formation of qualitatively new kinds of topological states.

Intracavity Squeezing Can Enhance Quantum-Limited Optomechanical Position Detection through Deamplification.

It has been predicted and experimentally demonstrated that by injecting squeezed light into an optomechanical device, it is possible to enhance the precision of a position measurement. Here, we present a fundamentally different approach where the squeezing is created directly inside the cavity by a nonlinear medium. Counterintuitively, the enhancement of the signal-to-noise ratio works by deamplifying precisely the quadrature that is sensitive to the mechanical motion without losing quantum information.

Nonlinear Radiation Pressure Dynamics in an Optomechanical Crystal.

Utilizing a silicon nanobeam optomechanical crystal, we investigate the attractor diagram arising from the radiation pressure interaction between a localized optical cavity at λ_{c}=1542  nm and a mechanical resonance at ω_{m}/2π=3.72  GHz. At a temperature of T_{b}≈10  K, highly nonlinear driving of mechanical motion is observed via continuous wave optical pumping.

Magnon dark modes and gradient memory.

Extensive efforts have been expended in developing hybrid quantum systems to overcome the short coherence time of superconducting circuits by introducing the naturally long-lived spin degree of freedom. Among all the possible materials, single-crystal yttrium iron garnet has shown up recently as a promising candidate for hybrid systems, and various highly coherent interactions, including strong and even ultrastrong coupling, have been demonstrated. One distinct advantage in these systems is that spins form well-defined magnon modes, which allows flexible and precise tuning.

QUANTUM MECHANICS. Quantum squeezing of motion in a mechanical resonator.

According to quantum mechanics, a harmonic oscillator can never be completely at rest. Even in the ground state, its position will always have fluctuations, called the zero-point motion. Although the zero-point fluctuations are unavoidable, they can be manipulated.

Pattern phase diagram for two-dimensional arrays of coupled limit-cycle oscillators.

Arrays of coupled limit-cycle oscillators represent a paradigmatic example for studying synchronization and pattern formation. We find that the full dynamical equations for the phase dynamics of a limit-cycle oscillator array go beyond previously studied Kuramoto-type equations. We analyze the evolution of the phase field in a two-dimensional array and obtain a "phase diagram" for the resulting stationary and nonstationary patterns.