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We propose a new protocol for preparing spin squeezed states in controllable atomic, molecular, and optical systems, with particular relevance to emerging optical clock platforms compatible with Rydberg interactions. By combining a short-ranged, soft-core potential with an external drive, we can transform naturally emerging Ising interactions into an XX spin model while opening a many-body gap. The gap helps maintain the system within a collective manifold of states where metrologically useful spin squeezing can be generated at a level comparable to the spin squeezing generated in systems with genuine all-to-all interactions. We examine the robustness of our protocol to experimentally-relevant decoherence and show favorable performance over typical protocols lacking gap protection., Comment: 5+4 pages, 3+3 figures

Quantum walks provide a framework for understanding and designing quantum algorithms that is both intuitive and universal. To leverage the computational power of these walks, it is important to be able to programmably modify the graph a walker traverses while maintaining coherence. Here, we do this by combining the fast, programmable control provided by optical tweezer arrays with the scalable, homogeneous environment of an optical lattice. Using this new combination of tools we study continuous-time quantum walks of single atoms on a 2D square lattice, and perform proof-of-principle demonstrations of spatial search using these walks. When scaled to more particles, the capabilities demonstrated here can be extended to study a variety of problems in quantum information science and quantum simulation, including the deterministic assembly of ground and excited states in Hubbard models with tunable interactions, and performing versions of spatial search in a larger graph with increased connectivity, where search by quantum walk can be more effective., Comment: 9 pages, 3 figures (main text); 13 pages, 8 figures (supplemental materials)

We report on the realization of a fast, scalable, and high-fidelity qubit architecture, based on $^{171}$Yb atoms in an optical tweezer array. We demonstrate several attractive properties of this atom for its use as a building block of a quantum information processing platform. Its nuclear spin of 1/2 serves as a long-lived and coherent two-level system, while its rich, alkaline-earth-like electronic structure allows for low-entropy preparation, fast qubit control, and high-fidelity readout. We present a near-deterministic loading protocol, which allows us to fill a 10$\times$10 tweezer array with 92.73(8)% efficiency and a single tweezer with 96.0(1.4)% efficiency. In the future, this loading protocol will enable efficient and uniform loading of target arrays with high probability, an essential step in quantum simulation and information applications. Employing a robust optical approach, we perform submicrosecond qubit rotations and characterize their fidelity through randomized benchmarking, yielding 5.2(5)$\times 10^{-3}$ error per Clifford gate. For quantum memory applications, we measure the coherence of our qubits with $T_2^*$=3.7(4) s and $T_2$=7.9(4) s, many orders of magnitude longer than our qubit rotation pulses. We measure spin depolarization times on the order of tens of seconds and find that this can be increased to the 100 s scale through the application of a several-gauss magnetic field. Finally, we use 3D Raman-sideband cooling to bring the atoms near their motional ground state, which will be central to future implementations of two-qubit gates that benefit from low motional entropy., This version includes a corrected discussion of the polarization for one of the single-beam Raman gates

The generation of long-lived entanglement on an optical clock transition is a key requirement to unlocking the promise of quantum metrology. Arrays of neutral atoms constitute a capable quantum platform for accessing such physics, where Rydberg-based interactions may generate entanglement between individually controlled and resolved atoms. To this end, we leverage the programmable state preparation afforded by optical tweezers along with the efficient strong confinement of a 3d optical lattice to prepare an ensemble of strontium atom pairs in their motional ground state. We engineer global single-qubit gates on the optical clock transition and two-qubit entangling gates via adiabatic Rydberg dressing, enabling the generation of Bell states, $|\psi\rangle = \frac{1}{\sqrt{2}}\left(|gg\rangle + i|ee\rangle \right)$, with a fidelity of $\mathcal{F}= 92.8(2.0)$%. For use in quantum metrology, it is furthermore critical that the resulting entanglement be long lived; we find that the coherence of the Bell state has a lifetime of $\tau_{bc} = 4.2(6)$ s via parity correlations and simultaneous comparisons between entangled and unentangled ensembles. Such Bell states can be useful for enhancing metrological stability and bandwidth. Further rearrangement of hundreds of atoms into arbitrary configurations using optical tweezers will enable implementation of many-qubit gates and cluster state generation, as well as explorations of the transverse field Ising model and Hubbard models with entangled or finite-range-interacting tunnellers.

Importance Despite the widespread use of systemic antibiotics to prevent infections in surgically treated patients with fracture, high rates of surgical site infection persist. Objective To examine the effect of intrawound vancomycin powder in reducing deep surgical site infections. Design, Setting, and Participants This open-label randomized clinical trial enrolled adult patients with an operatively treated tibial plateau or pilon fracture who met the criteria for a high risk of infection from January 1, 2015, through June 30, 2017, with 12 months of follow-up (final follow-up assessments completed in April 2018) at 36 US trauma centers. Interventions A standard infection prevention protocol with (n = 481) or without (n = 499) 1000 mg of intrawound vancomycin powder. Main Outcomes and Measures The primary outcome was a deep surgical site infection within 182 days of definitive fracture fixation. A post hoc comparison assessed the treatment effect on gram-positive and gram-negative-only infections. Other secondary outcomes included superficial surgical site infection, nonunion, and wound dehiscence. Results The analysis included 980 patients (mean [SD] age, 45.7 [13.7] years; 617 [63.0%] male) with 91% of the expected person-time of follow-up for the primary outcome. Within 182 days, deep surgical site infection was observed in 29 of 481 patients in the treatment group and 46 of 499 patients in the control group. The time-to-event estimated probability of deep infection by 182 days was 6.4% in the treatment group and 9.8% in the control group (risk difference, –3.4%; 95% CI, –6.9% to 0.1%;P = .06). A post hoc analysis of the effect of treatment on gram-positive (risk difference, –3.7%; 95% CI, –6.7% to –0.8%;P = .02) and gram-negative-only (risk difference, 0.3%; 95% CI, –1.6% to 2.1%;P = .78) infections found that the effect of vancomycin powder was a result of its reduction in gram-positive infections. Conclusions and Relevance Among patients with operatively treated tibial articular fractures at a high risk of infection, intrawound vancomycin powder at the time of definitive fracture fixation reduced the risk of a gram-positive deep surgical site infection, consistent with the activity of vancomycin. Trial Registration ClinicalTrials.gov Identifier:NCT02227446

The authors aimed to characterize surgical and functional outcomes of open fractures of the distal radius in patients younger than 65 years. At their level I trauma center, the authors conducted a retrospective review of 92 patients (age range, 16–64 years) who had 94 open fractures of the distal radius (average follow-up, 30 months; range, 3–95 months). Sixty-four fractures received definitive treatment at the time of initial débridement; 30 received definitive fixation and soft tissue coverage after staged débridement. Primary surgical outcome was development of deep surgical site infection requiring repeat surgical débridement; secondary surgical outcome was surgical complications requiring reoperation. Functional outcome was assessed by wrist range of motion. Overall infection rate was 15% (14 of 94 fractures). Seven (11%) of 64 fractures in the immediate definitive fixation group developed infection compared with 7 (23%) of 30 fractures in the staged treatment group ( P =.13). Twenty-one (33%) of 64 fractures in the immediate definitive fixation group required reoperation compared with 15 (50%) of 30 in the staged treatment group ( P =.11). Deep surgical site infections and surgical complications associated with open fractures of the distal radius are driven by soft tissue injury. [ Orthopedics . 2019; 42(4):219–225.]

Background: The purposes of this study were to validate an innovative, percutaneous method of monitoring femoral head (epiphyseal) perfusion intraoperatively in patients with slipped capital femoral epiphysis (SCFE) and to investigate an association between intraoperative perfusion and the subsequent development of osteonecrosis. Methods: A percutaneous screw fixation technique for SCFE was utilized. A fully threaded, cannulated, stainless-steel 7.0-mm screw was inserted into the epiphysis. The guidewire was removed, and a sterile intracranial pressure (ICP) probe was placed through the screw such that the tip was in the epiphyseal bone past the end of the screw. Intraoperative epiphyseal pressure and waveform were recorded. A prospective analysis of patients undergoing percutaneous screw fixation for unstable or stable SCFE or for prophylactic treatment with the use of this technique to evaluate femoral head perfusion was performed. Results: This technique was used in 23 patients (29 hips, including 15 hips with unstable SCFE, 11 with stable SCFE, and 3 treated prophylactically). Three hips (2 with unstable SCFE and 1 treated prophylactically) in 2 patients were eliminated from the analysis because of technical problems with the ICP monitor. All hips with stable SCFE and the prophylactically treated hips had measurable pulsatile flow that was synchronous with the patient’s heart rate at the initial time of probe insertion. Seven patients (7 hips) with unstable SCFE had measurable, pulsatile flow with initial insertion of the probe, and 6 patients (6 hips) with unstable SCFE had no measurable flow. We were able to demonstrate perfusion following a percutaneous capsular decompression in the patients with no initial flow. All patients left the operating room with measurable femoral head blood flow. At a mean follow-up of 1.6 years for hips with stable SCFE and 2.0 years for those with unstable SCFE, no hip subsequently developed radiographic evidence of osteonecrosis of the femoral head. No complications from the use of the ICP monitor occurred. Conclusions: Femoral head perfusion in patients with SCFE can be measured intraoperatively using this technique. Demonstrating femoral head perfusion before leaving the operating room was associated with the absence of osteonecrosis postoperatively. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Introduction and aim There is a paucity of literature regarding outcomes of open fractures of the distal radius. No study has detailed this injury or treatment strategy in the geriatric population. The purpose of this study was to determine the safety of immediate open reduction and internal fixation of geriatric open fractures of the distal radius. Methods A total of 21 geriatric patients with open fractures of the distal radius treated with a single definitive procedure were identified from a prospectively collected database. We reviewed patient demographics, injury characteristics and treatment specifics. Our primary outcome was surgical-site infection defined by need for antibiotics or repeat surgery. Our secondary outcome was need for other re-operation. Patients were contacted and functional scores obtained. Results Patients were followed up for an average of 26 months. One deep infection and one nonunion occurred, and they required repeat surgery. Four minor operative complications occurred, including stiffness requiring manipulation and prominent fixation devices requiring removal. Patients maintained an average wrist flexion–extension arc of 89° and pronation–supination arc of 137°. The average QuickDASH (shortened disabilities of the arm, shoulder and hand questionnaire) score was 17.4, indicating minimal disability of the upper extremity. Conclusions Immediate open reduction and internal fixation of geriatric open fractures of the distal radius yields adequate functional results with low risk of major complications.

Purpose Osteochondroplasty of the femoral head-neck junction can improve hip pain and function in patients with femoroacetabular impingement. We report our initial series of patients undergoing surgical treatment for symptomatic CAM type femoroacetabular impingement using a combined arthroscopic and mini-open approach. Materials and methods A retrospective chart review of 20 consecutive patients was performed. Seventeen patients had adequate follow-up for inclusion. Preoperative clinical and radiographic characteristics as well as intraoperative findings were obtained from patient records. Postoperative Harris Hip scores and VAS pain scores were recorded at final follow-up. Results At an average of 27.8 months (range 12-48 months), the mean Harris Hip score improved from 64.7 preoperatively to 86.8 (p < 0.001). The mean VAS pain score improved from 4.80 to 1.53 (p = 0.001). Two patients (11.7%) underwent total hip arthroplasty at an average of 15 months postoperatively. Fourteen patients (82%) stated they would have the procedure again. There were no significant complications. Conclusion Surgical treatment of CAM type femoroacetabular impingement using a combined arthroscopic and mini-open anterior hip approach has a low complication rate and improves functional and pain scores at short-term follow-up. Watters TS, Kaufman AM, Solic JM, Stinnett SS, Olson SA. Combined Arthroscopic and Mini-Open Treatment of CAM-Type Femoroacetabular Impingement. The Duke Orthop J 2012;2(1):60-65.

Recent advances in polyethylene fabrication have led to the introduction of highly cross-linked polyethylene tibial and patellar components for use in total knee arthroplasty (TKA) with the goal of reducing wear-related osteolysis. However, some reports suggest decreased mechanical strength as a result of the additional thermal and sterilization treatments in the manufacturing of implants. Complications related to the patella are among the most common causes of failure in TKA, but patellar component fracture is rare. The authors report a case of a highly cross-linked all-polyethylene patellar component that failed as a result of fracture in vivo in a patient 3 years after TKA.

The use of a pedicled flexor carpi ulnaris (FCU) muscle proximal turnover flap has been described previously for soft tissue reconstruction at the posterior elbow. Whereas consistent arterial supply to the FCU has been reported, the reliability of distal flap perfusion has not been confirmed. This study evaluated the vascular perfusion of an FCU turnover flap, based on the most proximal primary vascular pedicle that would permit a proximal turnover flap reconstruction to include the olecranon tip.In 12 fresh-frozen, proximal humeral human amputation specimens, the FCU flap was elevated from distal to proximal, preserving the most proximal primary vascular pedicle to the muscle belly that would permit flap coverage of the olecranon tip. The axillary artery was injected with India ink after ligation of radial and ulnar arteries at the wrist. After injection, each specimen was sectioned transversely at 0.5-cm increments to assess vascular perfusion of the muscle using loupe magnification.The distance from the olecranon tip to the distal FCU muscle belly was 25.9 cm. The primary vascular pedicle that would facilitate creation of a proximal turnover flap was, on average, 5.9 cm distal to the olecranon tip. Perfusion of FCU muscle as measured distal to this primary pedicle was present in 50% to 100% of the muscle belly at an average of 8.9 cm beyond the pedicle. Perfusion of 25% to 50% of the FCU muscle belly was present at an average of 11.1 cm beyond the pedicle. Perfusion became less consistent (25%) within the muscle belly at an average distance of 11.6 cm.Use of a proximally based, pedicled FCU muscle turnover flap provides a reliable option for soft tissue reconstruction at the posterior elbow. We observed consistent arterial perfusion of the muscle flap when preserving a proximal vascular pedicle 5.9 cm distal to the olecranon tip.

Periprosthetic joint infection in the acute setting is usually caused by gram-positive species and remains a major problem facing total joint surgeons. We report a case of a 53-year-old male who presented with drainage 3 weeks after primary total hip arthroplasty. Citrobacter koseri was cultured from an infected hematoma in his deep tissues. Surgical treatment included irrigation and debridement with femoral head and liner exchange. He received a 6-week course of ertapenem and is currently asymptomatic. We present C. koseri as a rare cause of acute periprosthetic infection and offer an effective treatment protocol.