Observing dynamical phases of BCS superconductors in a cavity QED simulator.

In conventional Bardeen-Cooper-Schrieffer superconductors1, electrons with opposite momenta bind into Cooper pairs due to an attractive interaction mediated by phonons in the material. Although superconductivity naturally emerges at thermal equilibrium, it can also emerge out of equilibrium when the system parameters are abruptly changed2-8. The resulting out-of-equilibrium phases are predicted to occur in real materials and ultracold fermionic atoms, but not all have yet been directly observed. Here we realize an alternative way to generate the proposed dynamical phases using cavity quantum electrodynamics (QED). Our system encodes the presence or absence of a Cooper pair in a long-lived electronic transition in 88Sr atoms coupled to an optical cavity and represents interactions between electrons as photon-mediated interactions through the cavity9,10. To fully explore the phase diagram, we manipulate the ratio between the single-particle dispersion and the interactions after a quench and perform real-time tracking of the subsequent dynamics of the superconducting order parameter using nondestructive measurements. We observe regimes in which the order parameter decays to zero (phase I)3,4, assumes a non-equilibrium steady-state value (phase II)2,3 or exhibits persistent oscillations (phase III)2,3. This opens up exciting prospects for quantum simulation, including the potential to engineer unconventional superconductors and to probe beyond mean-field effects like the spectral form factor11,12, and for increasing the coherence time for quantum sensing.

Exploring dynamical phase transitions with cold atoms in an optical cavity.

Interactions between atoms and light in optical cavities provide a means of investigating collective (many-body) quantum physics in controlled environments. Such ensembles of atoms in cavities have been proposed for studying collective quantum spin models, where the atomic internal levels mimic a spin degree of freedom and interact through long-range interactions tunable by changing the cavity parameters1-4. Non-classical steady-state phases arising from the interplay between atom-light interactions and dissipation of light from the cavity have previously been investigated5-11. These systems also offer the opportunity to study dynamical phases of matter that are precluded from existence at equilibrium but can be stabilized by driving a system out of equilibrium12-16, as demonstrated by recent experiments17-22. These phases can also display universal behaviours akin to standard equilibrium phase transitions8,23,24. Here, we use an ensemble of about a million strontium-88 atoms in an optical cavity to simulate a collective Lipkin-Meshkov-Glick model25,26, an iconic model in quantum magnetism, and report the observation of distinct dynamical phases of matter in this system. Our system allows us to probe the dependence of dynamical phase transitions on system size, initial state and other parameters. These observations can be linked to similar dynamical phases in related systems, including the Josephson effect in superfluid helium27, or coupled atomic28 and solid-state polariton29 condensates. The system itself offers potential for generation of metrologically useful entangled states in optical transitions, which could permit quantum enhancement in state-of-the-art atomic clocks30,31.

Bosonic Pair Production and Squeezing for Optical Phase Measurements in Long-Lived Dipoles Coupled to a Cavity.

We propose to simulate bosonic pair creation using large arrays of long-lived dipoles with multilevel internal structure coupled to an undriven optical cavity. Entanglement between the atoms, generated by the exchange of virtual photons through a common cavity mode, grows exponentially fast and is described by two-mode squeezing of effective bosonic quadratures. The mapping between an effective bosonic model and the natural spin description of the dipoles allows us to realize the analog of optical homodyne measurements via straightforward global rotations and population measurements of the electronic states, and we propose to exploit this for quantum-enhanced sensing of an optical phase (common and differential between two ensembles). We discuss a specific implementation based on Sr atoms and show that our sensing protocol is robust to sources of decoherence intrinsic to cavity platforms. Our proposal can open unique opportunities for next-generation optical atomic clocks.

Cavity-QED Quantum Simulator of Dynamical Phases of a Bardeen-Cooper-Schrieffer Superconductor.

We propose to simulate dynamical phases of a BCS superconductor using an ensemble of cold atoms trapped in an optical cavity. Effective Cooper pairs are encoded via the internal states of the atoms, and attractive interactions are realized via the exchange of virtual photons between atoms coupled to a common cavity mode. Control of the interaction strength combined with a tunable dispersion relation of the effective Cooper pairs allows exploration of the full dynamical phase diagram of the BCS model as a function of system parameters and the prepared initial state. Our proposal paves the way for the study of the nonequilibrium features of quantum magnetism and superconductivity by harnessing atom-light interactions in cold atomic gases.

Protocol for Precise Field Sensing in the Optical Domain with Cold Atoms in a Cavity.

In the context of quantum metrology, optical cavity-QED platforms have primarily been focused on the generation of entangled atomic spin states useful for next-generation frequency and time standards. Here, we report a complementary application: the use of optical cavities to generate nonclassical states of light for electric field sensing below the standard quantum limit. We show that cooperative atom-light interactions in the strong collective coupling regime can be used to engineer generalized atom-light cat states which enable quantum enhanced sensing of small displacements of the cavity field even in the presence of photon loss. We demonstrate that metrological gains of 10-20 dB below the standard quantum limit are within reach for current cavity-QED systems operating with long-lived alkaline-earth atoms.

Robust Spin Squeezing via Photon-Mediated Interactions on an Optical Clock Transition.

Cavity QED is a promising avenue for the deterministic generation of entangled and spin-squeezed states for quantum metrology. One archetypal scheme generates squeezing via collective one-axis twisting interactions. However, we show that in implementations using optical transitions in long-lived atoms the achievable squeezing is fundamentally limited by collectively enhanced emission into the cavity mode which is generated in parallel with the cavity-mediated spin-spin interactions. We propose an alternative scheme which generates a squeezed state that is protected from collective emission, and investigate its sensitivity to realistic sources of experimental noise and imperfections.

Pumped-Up SU(1,1) Interferometry.

Although SU(1,1) interferometry achieves Heisenberg-limited sensitivities, it suffers from one major drawback: Only those particles outcoupled from the pump mode contribute to the phase measurement. Since the number of particles outcoupled to these "side modes" is typically small, this limits the interferometer's absolute sensitivity. We propose an alternative "pumped-up" approach where all the input particles participate in the phase measurement and show how this can be implemented in spinor Bose-Einstein condensates and hybrid atom-light systems-both of which have experimentally realized SU(1,1) interferometry. We demonstrate that pumped-up schemes are capable of surpassing the shot-noise limit with respect to the total number of input particles and are never worse than conventional SU(1,1) interferometry. Finally, we show that pumped-up schemes continue to excel-both absolutely and in comparison to conventional SU(1,1) interferometry-in the presence of particle losses, poor particle-resolution detection, and noise on the relative phase difference between the two side modes. Pumped-up SU(1,1) interferometry therefore pushes the advantages of conventional SU(1,1) interferometry into the regime of high absolute sensitivity, which is a necessary condition for useful quantum-enhanced devices.

Diagnosis, Treatment, and Surgical Repair in a Case of Isolated Conjunctival Lichen Planus Causing Cicatricial Entropion.

A 50-year-old male presented with bilateral cicatricial entropion with subepithelial fibrosis and fornix foreshortening. Conjunctival biopsy showed lymphocytic infiltrate along the interface of the epithelium and lamina propria with linear, shaggy fibrinogen deposition along the epithelial basement membrane zone, supporting a diagnosis of lichen planus. The patient was treated with commercially available topical cyclosporine for 5 months after which bilateral lower eyelid splitting procedure with recession of the anterior lamella and complete excision of the lower eyelid lashes was performed.

Use of a subpalpebral lavage system as salvage therapy for Pseudomonas aeruginosa panophthalmitis due to an infected scleral buckle.

PURPOSE: To present a case and surgical technique for management of Pseudomonas aeruginosa panophthalmitis secondary to an infected scleral buckle. METHODS: Surgical technique video for management of an infected scleral buckle resulting in panophthalmitis with scleral buckle and suture explant and insertion of a subpalpebral lavage system. RESULTS: After two months, the visual acuity was restored to hand motion, likely secondary to a fibrotic secondary membrane, and the retina remain attached. This reports the first description of globe salvage for panophthalmitis from a P. aeruginosa-infected scleral buckle. CONCLUSION: This case encourages surgeons to remove all aspects of an exposed scleral buckle, including sutures, and emphasizes the importance of routine culture of all explanted material, even in the absence of clinical infection. In addition, this case encourages the use of a subpalpebral lavage in cases of severe P. aeruginosa ocular infections.

Active microbiota persist in dry permafrost and active layer from Elephant Head, Antarctica.

Dry permafrost is a challenging environment for microbial life due to cold, dry, and often oligotrophic conditions. In 2016, Elephant Head, Antarctica, was confirmed as the second site on Earth to contain dry permafrost. It is geographically distinct from the McMurdo Dry Valleys where dry permafrost has been studied previously. Here, we present the first study of the microbial activity, diversity, and functional potential of Elephant Head dry permafrost. Microbial activity was measured using radiorespiration assays with radiolabeled acetate as a carbon source at 5, 0, and -5°C. Low, but detectable, rates of microbial activity were measured in some samples at 0 and -5°C. This is distinct from previous studies of McMurdo Dry Valley dry permafrost which concluded that dry permafrost represents a cold-arid limit to life on the planet. The isolation of cold-adapted organisms from these soils, including one capable of subzero growth, further supports that the Elephant Head dry active layer and dry permafrost harbor viable microbial life, which may be active in situ. Metagenomic, 16S rRNA gene, and internal transcribed spacer and amplicon sequencing identified similar microbial communities to other Antarctic and cold environments. The Elephant Head microbial community appears to be adapted for survival in cold, dry, and oligotrophic conditions based on the presence of cold adaptation and stress response genes in the metagenomes. Together, our results show that dry permafrost environments do not exclude active microbial life at subzero temperatures, suggesting that the cold, dry soils of Mars may also not be as inhospitable as previously thought.

An Unnamed Human Oral Bergeyella sp. as the Cause of an Unusual Bacterial Keratitis.

Purpose. We report a case of bacterial keratitis secondary to an undescribed Bergeyella sp. Bergeyella spp. are not easily cultured, and many reports have identified unculturable isolates through broad-range bacterial polymerase chain reaction (PCR). Observations. A healthy 29-year-old male was attempting to repair an acrylic cannabis water pipe when it shattered and a fragment hit him in the left eye. Two weeks later, he presented with foreign body sensation, scleral injection, and photophobia that were refractory to prolonged corticosteroid therapy. Following a subconjunctival triamcinolone injection, the patient developed a hypopyon and multifocal, midstromal, epithelized corneal infiltrates. Broad-range PCR of the aqueous fluid detected deoxyribonucleic acid closely matching the Bergeyella genus. Empiric treatment directed toward gram-negative bacteria led to the clinical resolution of the inflammation. Conclusions and Importance. This is the first reported case of ocular inflammation secondary to a Bergeyella spp.. As broad-range PCR testing becomes more accessible, we anticipate that additional PCR-positive and culture-negative scenarios will occur.

A Rare Presentation of Metastatic Renal Cell Carcinoma Masquerading as Vitritis: A Case Report and Review of Literature.

We report a case of a 74-year-old gentleman who presented with floaters and decreased vision in the right eye after cataract surgery. His past medical history was significant for metastatic renal cell carcinoma (mRCC) to bone, lung and abdomen which was presumed stable for the last two years while on the tyrosine kinase inhibitor (TKI), pazopanib. Clinical examination revealed significant vitritis with a distinctive clumping of cells on the pre-retinal surface and posterior hyaloid face. Magnetic resonance imaging of the brain revealed new lesions suspicious for metastases. A diagnostic vitrectomy was performed to determine the nature of the vitritis and clear the visual axis. Cytopathologic evaluation of the vitreous demonstrated clusters of malignant cells that were positive for AE1/AE3 and PAX-8, and negative for the CD20, CD3, RCC, SOX-10 and S-100 immunohistochemical markers. The overall findings favored a metastatic RCC to the vitreous. Choroidal and retinal metastases from mRCC have been previously reported; however, vitreous involvement by mRCC with no evidence of retinal or choroidal mass has not been described. New treatments of mRCC include TKIs which target vascular endothelial growth factor receptors (VEGFRs). Herein, we analyze the factors that could have precipitated this unusual metastasis to the vitreous.

Observing the initial onset of retinal vasculitis as unilateral Birdshot Retinochoroiditis becomes bilateral: A case report.

Purpose: Birdshot Retinochoroiditis (BRC) is an uncommon but distinct form of bilateral posterior uveitis. It is generally of indolent onset, making early natural history difficult to study. Our report seeks to expand knowledge on the natural history of the onset of BRC. Observations: Our patient presented with clinical features that were consistent with unilateral BRC, despite it being defined as a bilateral condition. Over the course of one year he developed retinal vasculitis, vitritis and fundus features of BRC in the second eye. Conclusions and Importance: Although BRC is a bilateral disease, our case demonstrates that the onset may sometimes be sequential instead of simultaneous. Unilateral disease that is characteristic of BRC should be monitored for second-eye involvement with multi-modal imaging including fundus photography, angiography, perimetry, electroretinography, and optical coherence tomography of the macula with emphasis on the choroidal thickness.

Impact of COVID-19 on the Ophthalmology Residency Home-Institution Match Rate.

Purpose The aim of this study was to evaluate the ophthalmology residency match results to determine changes in the rate of home-institution matches during the coronavirus disease 2019 (COVID-19) pandemic. Methods Aggregate deidentified summary match result data from 2017 to 2022 was obtained from the Association of University Professors of Ophthalmology and the San Francisco (SF) Match. A chi-squared test was performed to determine if the rate of candidate matching to the home residency program in ophthalmology was higher in the post-COVID-19 compared with pre-COVID-19 match years. A literature review using PubMed was performed of other medical subspecialty match rates to home institution during the same study period. Results A chi-squared test for difference in proportions confirmed a significantly higher chance of matching to the home program for ophthalmology in the post-COVID-19, SF Match year of 2021 to 2022 compared with 2017 to 2020 ( p = 0.001). Other medical specialties including otolaryngology, plastic surgery, and dermatology also showed similar increased home institution residency match rates during the same time period. Although neurosurgery and urology also had increased trend rates for home institution match rates, these results did not reach statistical significance. Conclusions The ophthalmology home-institution residency SF Match rate was significantly increased during the COVID-19 pandemic year 2021 to 22. This mirrors a trend reported in other specialties including the otolaryngology, dermatology, and plastic surgery in the 2021 match. Additional study will be required to identify factors leading to this observation.

Paraneoplastic Conjunctival Acanthosis Nigricans: A Case Report.

PURPOSE: To report a patient who presented with red eye and diffuse palpebral conjunctival thickening and papillary growth bilaterally. METHODS: A 63-year-old woman with a medical history of stage IV adenocarcinoma of the lung with metastasis to the bone, the lung, and the lymph nodes presented with redness and irritation of both eyes for 3 months. The patient has been treated with topical corticosteroids for 3 weeks with no relief of symptoms. RESULTS: Clinical examination and pathology report of conjunctival biopsy confirmed the diagnosis of conjunctival acanthosis nigricans. CONCLUSIONS: Conjunctival acanthosis nigricans is a rare paraneoplastic condition that resembles papilloma and can present a challenge in diagnosis. When acanthosis nigricans occurs after the diagnosis of malignancy, it can be an indicator of progression of the underlying condition. The diagnosis of conjunctival acanthosis nigricans in a patient with no history of cancer should prompt clinicians for further malignancy workup.

Quantum-enhanced sensing of displacements and electric fields with two-dimensional trapped-ion crystals.

Fully controllable ultracold atomic systems are creating opportunities for quantum sensing, yet demonstrating a quantum advantage in useful applications by harnessing entanglement remains a challenging task. Here, we realize a many-body quantum-enhanced sensor to detect displacements and electric fields using a crystal of ~150 trapped ions. The center-of-mass vibrational mode of the crystal serves as a high-Q mechanical oscillator, and the collective electronic spin serves as the measurement device. By entangling the oscillator and collective spin and controlling the coherent dynamics via a many-body echo, a displacement is mapped into a spin rotation while avoiding quantum back-action and thermal noise. We achieve a sensitivity to displacements of 8.8 ± 0.4 decibels below the standard quantum limit and a sensitivity for measuring electric fields of 240 ± 10 nanovolts per meter in 1 second. Feasible improvements should enable the use of trapped ions in searches for dark matter.