Erratum: Accuracy of the Quantum Regression Theorem for Photon Emission from a Quantum Dot [Phys. Rev. Lett. 127, 100402 (2021)].

This corrects the article DOI: 10.1103/PhysRevLett.127.100402.

Two-Photon Excitation Sets Limit to Entangled Photon Pair Generation from Quantum Emitters.

Entangled photon pairs are key to many novel applications in quantum technologies. Semiconductor quantum dots can be used as sources of on-demand, highly entangled photons. The fidelity to a fixed maximally entangled state is limited by the excitonic fine-structure splitting. This work demonstrates that, even if this splitting is absent, the degree of entanglement cannot reach unity when the excitation pulse in a two-photon resonance scheme has a finite duration. The degradation of the entanglement has its origin in a dynamically induced splitting of the exciton states caused by the laser pulse itself. Hence, in the setting explored here, the excitation process limits the achievable concurrence for entangled photons generated in an optically excited four-level quantum emitter.

Accuracy of the Quantum Regression Theorem for Photon Emission from a Quantum Dot.

The quantum regression theorem (QRT) is the most widely used tool for calculating multitime correlation functions for the assessment of quantum emitters. It is an approximate method based on a Markov assumption for environmental coupling. In this Letter we quantify properties of photons emitted from a single quantum dot coupled to phonons. For the single-photon purity and the indistinguishability, we compare numerically exact path-integral results with those obtained from the QRT. It is demonstrated that the QRT systematically overestimates the influence of the environment for typical quantum dots used in quantum information technology.

Femtosecond Transfer and Manipulation of Persistent Hot-Trion Coherence in a Single CdSe/ZnSe Quantum Dot.

Ultrafast transmission changes around the fundamental trion resonance are studied after exciting a p-shell exciton in a negatively charged II-VI quantum dot. The biexcitonic induced absorption reveals quantum beats between hot-trion states at 133 GHz. While interband dephasing is dominated by relaxation of the P-shell hole within 390 fs, trionic coherence remains stored in the spin system for 85 ps due to Pauli blocking of the triplet electron. The complex spectrotemporal evolution of transmission is explained analytically by solving the Maxwell-Liouville equations. Pump and probe polarizations provide full control over amplitude and phase of the quantum beats.

Detachment in Fusion Plasmas with Symmetry Breaking Magnetic Perturbation Fields.

Power exhaust from the bulk plasma is significantly altered by symmetry breaking magnetic perturbation fields, because these create direct connections (perturbed field lines) from the confined high temperature plasma to solid surfaces. The same amount of power is distributed among those new exhaust channels as for a symmetric magnetic configuration, which reduces the local upstream heat flux flowing down the perturbed field lines, thereby making access to detachment easier (i.e., at lower upstream density) for the divertor plasma near the location corresponding to the symmetric magnetic separatrix. However, the divertor plasma regions with connection to the bulk plasma are extended nonaxisymmetrically further outside, where significant heat loads occur, unlike in the symmetric configuration. The temperature remains high at those locations, which reduces the divertor plasma dissipation capacity, making the mitigation of heat loads more difficult to achieve.

Picosecond Control of Quantum Dot Laser Emission by Coherent Phonons.

A picosecond acoustic pulse can be used to control the lasing emission from semiconductor nanostructures by shifting their electronic transitions. When the active medium, here an ensemble of (In,Ga)As quantum dots, is shifted into or out of resonance with the cavity mode, a large enhancement or suppression of the lasing emission can dynamically be achieved. Most interesting, even in the case when gain medium and cavity mode are in resonance, we observe an enhancement of the lasing due to shaking by coherent phonons. In order to understand the interactions of the nonlinearly coupled photon-exciton-phonon subsystems, we develop a semiclassical model and find an excellent agreement between theory and experiment.

Machine learning classification of OARSI-scored human articular cartilage using magnetic resonance imaging.

OBJECTIVE: The purpose of this study is to evaluate the ability of machine learning to discriminate between magnetic resonance images (MRI) of normal and pathological human articular cartilage obtained under standard clinical conditions. METHOD: An approach to MRI classification of cartilage degradation is proposed using pattern recognition and multivariable regression in which image features from MRIs of histologically scored human articular cartilage plugs were computed using weighted neighbor distance using compound hierarchy of algorithms representing morphology (WND-CHRM). The WND-CHRM method was first applied to several clinically available MRI scan types to perform binary classification of normal and osteoarthritic osteochondral plugs based on the Osteoarthritis Research Society International (OARSI) histological system. In addition, the image features computed from WND-CHRM were used to develop a multiple linear least-squares regression model for classification and prediction of an OARSI score for each cartilage plug. RESULTS: The binary classification of normal and osteoarthritic plugs yielded results of limited quality with accuracies between 36% and 70%. However, multiple linear least-squares regression successfully predicted OARSI scores and classified plugs with accuracies as high as 86%. The present results improve upon the previously-reported accuracy of classification using average MRI signal intensities and parameter values. CONCLUSION: MRI features detected by WND-CHRM reflect cartilage degradation status as assessed by OARSI histologic grading. WND-CHRM is therefore of potential use in the clinical detection and grading of osteoarthritis.

Deep modeling of plasma and neutral fluctuations from gas puff turbulence imaging.

The role of turbulence in setting boundary plasma conditions is presently a key uncertainty in projecting to fusion energy reactors. To robustly diagnose edge turbulence, we develop and demonstrate a technique to translate brightness measurements of HeI line radiation into local plasma fluctuations via a novel integrated deep learning framework that combines neutral transport physics and collisional radiative theory for the 33D - 23P transition in atomic helium with unbounded correlation constraints between the electron density and temperature. The tenets for experimental validity are reviewed, illustrating that this turbulence analysis for ionized gases is transferable to both magnetized and unmagnetized environments with arbitrary geometries. Based on fast camera data on the Alcator C-Mod tokamak, we present the first two-dimensional time-dependent experimental measurements of the turbulent electron density, electron temperature, and neutral density, revealing shadowing effects in a fusion plasma using a single spectral line.

Lattice fluctuations at a double phonon frequency with and without squeezing: an exactly solvable model of an optically excited quantum dot.

Time-dependent lattice fluctuations of an optically excited strongly confined quantum dot are investigated with the aim to analyze the characteristics commonly used for identifying the presence of squeezed phonon states. It is demonstrated that the appearance of fluctuations oscillating with twice the phonon frequency, commonly regarded as a clear indication of squeezed states, cannot be considered as such. The source of the discrepancy with earlier investigations is discussed. Conditions for generating a squeezed state by using a two-pulse excitation are analyzed.

Resonant pedestal pressure reduction induced by a thermal transport enhancement due to stochastic magnetic boundary layers in high temperature plasmas.

Good alignment of the magnetic field line pitch angle with the mode structure of an external resonant magnetic perturbation (RMP) field is shown to induce modulation of the pedestal electron pressure p(e) in high confinement high rotation plasmas at the DIII-D tokamak with a shape similar to ITER, the next step tokamak experiment. This is caused by an edge safety factor q95 resonant enhancement of the thermal transport, while in contrast, the RMP induced particle pump out does not show a significant resonance. The measured p(e) reduction correlates to an increase in the modeled stochastic layer width during pitch angle variations matching results from resistive low rotation plasmas at the TEXTOR tokamak. These findings suggest a field line pitch angle resonant formation of a stochastic magnetic edge layer as an explanation for the q95 resonant character of type-I edge localized mode suppression by RMPs.

Effective detection of spatio-temporal carrier dynamics by carrier capture.

The spatio-temporal dynamics of electrons moving in a 2D plane is challenging to detect when the required resolution shrinks simultaneously to nanometer length and subpicosecond time scale. We propose a detection scheme relying on phonon-induced carrier capture from 2D unbound states into the bound states of an embedded quantum dot. This capture process happens locally and here we explore if this locality is sufficient to use the carrier capture process as detection of the ultrafast diffraction of electrons from an obstacle in the 2D plane. As an example we consider an electronic wave packet traveling in a semiconducting monolayer of the transition metal dichalcogenide MoSe2, and we study the scattering-induced dynamics using a single particle Lindblad approach. Our results offer a new way to high resolution detection of the spatio-temporal carrier dynamics.

Identification of the stimulated hemiretina in primary school children and adults based on left and right hemifield pattern reversal visual evoked potentials--a comparative study.

OBJECTIVES: The analysis of left and right hemifield pattern-reversal visual evoked potentials (PVEPs) in children and the identification of the stimulated hemiretina testing different identification procedures previously applied to adults. METHODS: Lateral hemifield PVEPs were recorded in 40 children (6-11 years) and 27 adults (25-40 years) from, at least, 19 standard electrodes. Two procedures were tested for the determination of the stimulated hemifield: firstly, the evaluation of the values of instantaneous frequency at the occipital electrodes at P100 latency (determined by the global field power), and secondly, the application of a generalised dynamic neural network (GDNN) using the PVEP time course at selected electrode positions as the external input. RESULTS: P100 latency as well as P100 amplitude over the contralateral occiput in children were significantly greater than in adults. Contrary to the behaviour in adults, instantaneous frequency is not a robust identifier of left and right hemiretina stimulation in children. The best identification performances were achieved when using group trained GDNNs with the bipolar difference signals of electrodes P3/P4 or T5/T6 as the external input. CONCLUSIONS: The PVEPs at electrodes P3/P4 and T5/T6 contain essential information for the determination of the stimulated hemifield. This should be further considered during the development of on-line procedures for automatic PVEP detection in future studies.

Unusual subcutaneous sarcoidosis of the face.

Two unusual cases of sarcoidosis manifesting as subcutaneous masses of the face are reported: in the first, the lesion occurred at the site of an osteotomy for rhinoplasty and was the initial clinical manifestation of sarcoidosis; in the second, the skin lesion was part of a multisystemic disease. The cases were documented with CT. Sarcoidosis should be added to the differential of soft-tissue masses of the face.

Isolated Castleman disease of the neck: MR findings.

Castleman disease in an 11-year-old girl appeared as a neck mass that grew despite antibiotic treatment. MR showed a well-defined solid mass, isointense with muscle on short-repetition-time/short-echo-time images, with a stellate area of central hypointensity on long-repetition-time/long-echo-time images, that did not enhance with gadolinium.

Neodymium:YAG laser therapy for pseudophakic pupillary block.

Pupillary block occurred in six patients with anterior chamber intraocular lens implants. After medical therapy failed, the Nd:YAG laser was used to break the hyaloid face in the pupillary and iridectomy apertures. Iridotomies were also produced at the sites of bulging iris. Following laser treatment the anterior chambers deepened and there were no further signs or symptoms of pupillary block. The Nd:YAG laser proved to be a useful treatment for pseudophakic pupillary block.

Auditory distortion.

The auditory system responds to pulsatile energy flow from the environment. Compression and rarefaction of gaseous molecular mass is transduced into electromechanical forms, in order to produce an effect at the cortical level. For energy input to have consistent meaning, transduction must preserve information coded within the pattern of energy flow. Distortion, or alteration of the original form, occurs in many ways throughout the chain of generation/transmission/reception/interpretation. Parameters of energy flow are discussed, and distortion of each parameter is presented in a context which permits the development of a distortion-based analysis of common clinical problems in otolaryngology.

Alternatives to packing in septorhinoplasty.

Nasal packing is considered routine by most physicians and patients at the completion of nasal and septal surgery. Yet the rationale for this maneuver is not clearly defined by reported investigation or logical analysis. We discuss 75 consecutive nasal surgical procedures completed without packing. There were two postoperative episodes of bleeding, both from pyriform aperture incisions for lateral osteotomy and both managed in the recovery room with an absorbable gelatin sponge. Technical refinements such as scrupulous preoperative history taking, through-and-through suturing of the entire septal flaps, small-caliber osteotomy, meticulous closure of all intranasal incisions, and proper application of a conforming dressing are essential for hemostasis. We offer specific procedural guidance to minimize the risk of postoperative nasal bleeding.

Laser resurfacing of silicone-injected skin: the "silicone flash" revisited.

OBJECTIVE: To determine whether prior silicone injection increases the risks associated with carbon dioxide laser resurfacing. DESIGN: Laboratory determination of the effect of laser energy on liquid silicone; histologic evaluation of silicone-injected skin after lasing; and histologic demonstration of silicone deposits in all layers of dermis years after injection of silicone as filler fluid. SETTING: Tertiary care medical center. PATIENT-RELATED DATA: Histologic examination of freshly excised skin injected with microdroplets of liquid silicone and subjected to application of carbon dioxide laser energy; histologic examination of skin excised years after silicone injection. INTERVENTIONS: High-speed clinical photographic imaging of the effect of laser energy on silicone fluid; histologic examination of hematoxylin-eosin-stained sections of skin injected with liquid silicone and subsequently lased. MAIN OUTCOME MEASURES: Response of liquid silicone to application of laser energy; effect of this response on surrounding normal skin. RESULTS: Exposure of microdroplets of liquid silicone to carbon dioxide laser energy produced flaring with frank flame. Flaring of dermal silicone caused collateral skin damage. CONCLUSIONS: Prior injection with liquid silicone is a relative contraindication to cutaneous resurfacing with the carbon dioxide laser. Surgical excision of silicone-injected skin may be preferable for many patients. A strenuous needs assessment should be done, alternatives for skin rejuvenation considered, and comprehensive informed consent obtained from the patient before embarking on laser resurfacing of silicone-injected skin.

Tumefactive cartilage proliferation after rhinoplasty. A newly reported complication.

OBJECTIVE: To describe and document the development of tumoral proliferation of cartilage in 4 patients after nasal surgery, a complication that, to our knowledge, has not been reported before. DESIGN: Similar postoperative nasal masses were excised from 4 patients who underwent rhinoplasty. Histopathologic evaluation was carried out to identify the nature of the lesions and to provide a basis for rational management of similar lesions subsequently encountered. SETTING: Academic tertiary referral center. PARTICIPANTS: Four healthy patients (3 women and 1 man) ranging in age from 21 to 49 years. Two of the patients underwent routine rhinoplasty with resection of cephalic margins of alar cartilages, and 2 underwent augmentation procedures with implantation of auricular cartilage. INTERVENTION: Discrete firm masses were excised from each patient's nose approximately 1 year after the most recent rhinoplastic procedure was performed. Histological evaluation was carried out on each specimen. RESULTS: All 4 masses were found to consist of tumefactive proliferation of cartilage. Clonal proliferation and mild nuclear atypia were observed. CONCLUSIONS: After rhinoplasty, progressive asymmetrical fullness in or adjacent to cartilaginous structures or graft material should suggest the possibility of tumefactive proliferation of cartilage and should be evaluated with surgical exploration. All areas of thickened cartilage should be excised completely, with immediate auricular cartilage reconstruction of resulting anatomical defects. Perichondrium should be completely removed from auricular cartilage implants in the nose, and mechanical injury to the graft should be minimized. We strongly caution against morsellizing dorsal cartilage implants for nasal reconstruction.

Prospective evaluation of novel system for jejunal feeding.

BACKGROUND: Enteral nutrition should be restored immediately after trauma, acute lesion, or surgical intervention. Nutrition through nasogastric tubes is often not feasible in patients in the posttraumatic state in medical intensive care units because of recurrent episodes of gastroesophageal reflux and subsequent aspiration due to gastric paresis. Placement of nasojejunal tubes with available techniques is unreliable. METHODS: We developed a new combined catheter system for jejunal delivery and simultaneous drainage of gastric juice (Cath-in-Cath, PreOx-RS, Germany). CONCLUSION: In this article, this new tube system is presented. The safety and excellent efficacy of the novel system for enteral nutrition therapy are reported in the first series of patients worldwide.