Superconducting diode effect and interference patterns in kagome CsV3Sb5.

The interplay among frustrated lattice geometry, non-trivial band topology and correlation yields rich quantum states of matter in kagome systems1,2. A series of recent members in this family, AV3Sb5 (A = K, Rb or Cs), exhibit a cascade of symmetry-breaking transitions3, involving the 3Q chiral charge ordering4-8, electronic nematicity9,10, roton pair density wave11 and superconductivity12. The nature of the superconducting order is yet to be resolved. Here we report an indication of dynamic superconducting domains with boundary supercurrents in intrinsic CsV3Sb5 flakes. The magnetic field-free superconducting diode effect is observed with polarity modulated by thermal histories, suggesting that there are dynamic superconducting order domains in a spontaneous time-reversal symmetry-breaking background. Strikingly, the critical current exhibits double-slit superconductivity interference patterns when subjected to an external magnetic field. The characteristics of the patterns are modulated by thermal cycling. These phenomena are proposed as a consequence of periodically modulated supercurrents flowing along certain domain boundaries constrained by fluxoid quantization. Our results imply a time-reversal symmetry-breaking superconducting order, opening a potential for exploring exotic physics, for example, Majorana zero modes, in this intriguing topological kagome system.

Interlayer-Coupling-Driven High-Temperature Superconductivity in La_{3}Ni_{2}O_{7} under Pressure.

The newly discovered high-temperature superconductivity in La_{3}Ni_{2}O_{7} under pressure has attracted a great deal of attention. The essential ingredient characterizing the electronic properties is the bilayer NiO_{2} planes coupled by the interlayer bonding of 3d_{z^{2}} orbitals through the intermediate oxygen atoms. In the strong coupling limit, the low-energy physics is described by an intralayer antiferromagnetic spin-exchange interaction J_{∥} between 3d_{x^{2}-y^{2}} orbitals and an interlayer one J_{⊥} between 3d_{z^{2}} orbitals. Taking into account Hund's rule on each site and integrating out the 3d_{z^{2}} spin degree of freedom, the system reduces to a single-orbital bilayer t-J model based on the 3d_{x^{2}-y^{2}} orbital. By employing the slave-boson approach, the self-consistent equations for the bonding and pairing order parameters are solved. Near the physically relevant 1/4-filling regime (doping δ=0.3∼0.5), the interlayer coupling J_{⊥} tunes the conventional single-layer d-wave superconducting state to the s-wave one. A strong J_{⊥} could enhance the interlayer superconducting order, leading to a dramatically increased T_{c}. Interestingly, there could exist a finite regime in which an s+id state emerges.

Bilayer t-J-J_{⊥} Model and Magnetically Mediated Pairing in the Pressurized Nickelate La_{3}Ni_{2}O_{7}.

The recently discovered nickelate superconductor La_{3}Ni_{2}O_{7} has a high transition temperature near 80 K under pressure, providing an additional avenue for exploring unconventional superconductivity. Here, with state-of-the-art tensor-network methods, we study a bilayer t-J-J_{⊥} model for La_{3}Ni_{2}O_{7} and find a robust s-wave superconductive (SC) order mediated by interlayer magnetic couplings. Large-scale density matrix renormalization group calculations find algebraic pairing correlations with Luttinger parameter K_{SC}≲1. Infinite projected entangled-pair state method obtains a nonzero SC order directly in the thermodynamic limit, and estimates a strong pairing strength Δ[over ¯]_{z}∼O(0.1). Tangent-space tensor renormalization group simulations elucidate the temperature evolution of SC pairing and further determine a high SC temperature T_{c}^{*}/J∼O(0.1). Because of the intriguing orbital selective behaviors and strong Hund's rule coupling in the compound, t-J-J_{⊥} model has strong interlayer spin exchange (while negligible interlayer hopping), which greatly enhances the SC pairing in the bilayer system. Such a magnetically mediated pairing has also been observed recently in the optical lattice of ultracold atoms. Our accurate and comprehensive tensor-network calculations reveal a robust SC order in the bilayer t-J-J_{⊥} model and shed light on the pairing mechanism of the high-T_{c} nickelate superconductor.

Analysis of the clinical efficacy of visualization of percutaneous endoscopic lumbar discectomy combined with annulus fibrosus suture in lumbar disc herniation.

The objective of this study is to compare the clinical effectiveness of visualization of percutaneous endoscopic lumbar discectomy (VPELD) combined with annulus fibrosus suture technique and simple percutaneous endoscopic lumbar discectomy (PELD) technique in the treatment of lumbar disc herniation. A retrospective analysis was conducted on 106 cases of lumbar disc herniation treated with foraminoscopic technique at our hospital from January 2020 to February 2022. Among them, 33 cases were treated with VPELD combined with annulus fibrosus suture in group A, and 73 cases were treated with PELD in group B. The preoperative and postoperative visual analogue scale (VAS), functional index (Oswestry Disability Index, ODI), healing of the annulus fibrosus, intervertebral space height, and postoperative recurrence were recorded and compared between the two groups. All patients underwent preoperative and postoperative MRI examinations, and the average follow-up period was 12 ± 2 months. Both groups showed significant improvements in postoperative VAS and ODI scores compared to the preoperative scores (P < 0.05), with no statistically significant difference between the groups during the same period (P > 0.05). There was no significant decrease in intervertebral space between the two groups after surgery (P > 0.05). Group A showed significantly lower postoperative recurrence rate and better annulus fibrosus healing compared to group B (P < 0.05). The VPELD combined with annulus fibrosus suture technique is a safe, feasible, and effective procedure for the treatment of lumbar disc herniation. When the indications are strictly adhered to, this technique can effectively reduce the postoperative recurrence rate and reoperation rate. It offers satisfactory clinical efficacy and can be considered as an alternative treatment option for eligible patients.

Charge-4e superconductivity and chiral metal in 45°-twisted bilayer cuprates and related bilayers.

The material realization of charge-4e/6e superconductivity (SC) is a big challenge. Here, we propose to realize charge-4e SC in maximally-twisted homobilayers, such as 45∘-twisted bilayer cuprates and 30∘-twisted bilayer graphene, referred to as twist-bilayer quasicrystals (TB-QC). When each monolayer hosts a pairing state with the largest pairing angular momentum, previous studies have found that the second-order interlayer Josephson coupling would drive chiral topological SC (TSC) in the TB-QC. Here we propose that, above the Tc of the chiral TSC, either charge-4e SC or chiral metal can arise as vestigial phases, depending on the ordering of the total- and relative-pairing-phase fields of the two layers. Based on a thorough symmetry analysis to get the low-energy effective Hamiltonian, we conduct a combined renormalization-group and Monte-Carlo study and obtain the phase diagram, which includes the charge-4e SC and chiral metal phases.

Evidence for Quantum Stripe Ordering in a Triangular Optical Lattice.

Understanding strongly correlated quantum materials, such as high-T_{c} superconductors, iron-based superconductors, and twisted bilayer graphene systems, remains as one of the outstanding challenges in condensed matter physics. Quantum simulation with ultracold atoms in particular optical lattices, which provide orbital degrees of freedom, is a powerful tool to contribute new insights to this endeavor. Here, we report the experimental realization of an unconventional Bose-Einstein condensate of ^{87}Rb atoms populating degenerate p orbitals in a triangular optical lattice, exhibiting remarkably long coherence times. Using time-of-flight spectroscopy, we observe that this state spontaneously breaks the rotational symmetry and its momentum spectrum agrees with the theoretically predicted coexistence of exotic stripe and loop-current orders. Like certain strongly correlated electronic systems with intertwined orders, such as high-T_{c} cuprate superconductors, twisted bilayer graphene, and the recently discovered chiral density-wave state in kagome superconductors AV_{3}Sb_{5} (A=K, Rb, Cs), the newly demonstrated quantum state, in spite of its markedly different energy scale and the bosonic quantum statistics, exhibits multiple symmetry breakings at ultralow temperatures. These findings hold the potential to enhance our comprehension of the fundamental physics governing these intricate quantum materials.

Clinical efficacy of transforaminal endoscopic lumbar discectomy for lumbar degenerative diseases: A minimum 6-year follow-up.

Background: Transforaminal Endoscopic Lumbar Discectomy (TELD) is widely applied for lumbar degenerative disease (LDDs) and satisfactory short-term outcomes have been achieved. However, the mid-term and long-term follow-up of this technique is still lacking. Objective: To retrospectively analyze the mid-term clinical efficacy of TELD for single-level LDD and its effect on intervertebral disc degeneration with a minimum of 6-year follow-up. Methods: 64 patients with single-level LDDs (lumbar disc herniation, lumbar spinal stenosis) who underwent TELD under local anesthesia in our department from December 2014 to December 2015 were observed. Visual analog scale (VAS), Japanese Orthopaedic Association evaluation treatment (JOA) score and Oswestry Disability Index (ODI) were calculated and compared before operation, 3 months after operation, 6 months after operation, 1 year after operation and at the last follow-up. Disc Height (DH), disc range of motion (ROM) and disc degeneration on standard lumbar lateral radiographs before operation and at the last follow-up were determined. Recurrence rate and operation-related complications during follow-up were recorded. Results: 64 cases were followed up for 6.4 ± 0.1 years. There were no complications such as infection, epidural hematoma and nerve root injury. 1 patient (1.67%) was found to have dural rupture and cauda equina hernia during the operation. There were significant differences in VAS, JOA, ODI between preoperative and postoperative 3 months, 6 months, 1 year and last follow-up (P < 0 01), VAS, JOA, ODI at 3 months after operation were different from 6 months after operation (P < 0 05), and there were significant differences compared with preoperative, 1 year after operation and last follow up (P < 0 01). VAS, JOA and ODI at 6 months after operation were significantly different from those before operation (P < 0.01), but not significantly different from those at 1 year after operation and the last follow-up (P > 0.05). There was no significant difference in DH, ROM and the Pfirrmann grade of intervertebral disc preoperative and the last follow-up. During the follow-up period, 3 patients (4.69%) were recurrent, 13 patients (20.31%) had various degrees of postoperative dysesthesia (POD), and 3 patients (4.69%) had various degrees of muscle weakness. Conclusion: TELD has a satisfactory mid-term efficacy, and has no significant effect on the DH, the stability of the intervertebral disc space, or on intervertebral disc degeneration. However, as expected, TELD was associated with some complications including recurrent disc herniation and POD.

[Research on the clinical application of drainage tube after the operation of percutaneous endoscopic lumbar discectomy].

OBJECTIVE: To investigate the clinical significance and related factors of drainage tube after percutaneous endoscopic lumbar discectomy(PELD). METHODS: The clinical data of 151 patients with lumbar disc herniation who underwent PELD from January 2019 to September 2019 was retrospectively analyzed. According to whether the drainage tube was used after operation, the patients were divided into drainage tube group and non drainage tube group. The placement time and total drainage volume were recorded. The characteristics of patients, such as age, gender, body mass index, lumbar disc herniation segment, smoking history, basic diseases and whether taking anticoagulants, were analyzed by single factor and multiple factor. RESULTS: Drainage tubes were used in 32 patients after PELD. There were statistical differences in visual analogue scale(VAS) and Japanese Orthopaedic Assiciation(JOA) scores between postoperative and preoperative of that in two groups(P<0.05). There were statistical differences in VAS and JOA scores at discharge between two groups(P<0.05), while there were no statistical differences at other time points(P>0.05). Univariate analysis showed that age, basic diseases and whether taking anticoagulants were related to the use of drainage tube, but gender, body mass index, lumbar disc herniation segment and smoking history were not significantly related to the use of drainage tube. Multivariate analysis showed that elderly patients, complicated with hypertension and diabetes, taking anticoagulants were related to the use of drainage tube. CONCLUSION: The use of drainage tube after percutaneous endoscopic lumbar discectomy can improve the symptoms of lumbar and leg pain in early stage. For elderly patients with hypertension, diabetes and taking anticoagulants drugs, drainage tube can be considered after transforaminal endoscopy.

Risk factors and management strategies for cerebrospinal fluid leakage following lumbar posterior surgery.

OBJECTIVE: To analyze the risk factors of cerebrospinal fluid leakage (CSFL) following lumbar posterior surgery and summarize the related management strategies. METHODS: A retrospective analysis was performed on 3179 patients with CSFL strategies lumbar posterior surgery in our hospital from January 2019 to December 2020. There were 807 cases of lumbar disc hemiation (LDH), 1143 cases of lumbar spinal stenosi (LSS), 1122 cases of lumbar spondylolisthesis(LS), 93 cases of lumbar degenerative scoliosis(LDS),14 cases of lumbar spinal benign tumor (LST). Data of gender, age, body mass index(BMI), duration of disease, diabete, smoking history, preoperative epidural steroid injection, number of surgical levels, surgical methods (total laminar decompression, fenestration decompression), revision surgery, drainage tube removal time, suture removal time, and complications were recorded. RESULTS: The incidence of 115 cases with cerebrospinal fluid leakage, was 3.6% (115/3179).One-way ANOVA showed that gender, body mass index (BMI), smoking history, combined with type 2 diabetes and surgical method had no significant effect on CSFL (P > 0.05). Age, type of disease, duration of disease, preoperative epidural steroid injection, number of surgical levels and revision surgery had effects on CSFL (P < 0.05). Multivariate Logistic regression analysis showed that type of disease, preoperative epidural steroid injection, number of surgical levels and revision surgery were significantly affected CSFL (P < 0.05).Drainage tube removal time of CSFL patients ranged from 7 to 11 days, with an average of 7.1 ± 0.5 days, drainage tube removal time of patients without CSFL was 1-3 days, with an average of 2.0 ± 0.1 days, and there was a statistical difference between the two groups (P < 0.05).The removal time of CSFL patients was 12-14 days, with an average of 13.1 ± 2.7 days, and the removal time of patients without CSFL was 10-14 days, with an average of 12.9 ± 2.2 days, there was no statistically significant difference between the two groups (P > 0.05). CONCLUSION: Type of disease, preoperative epidural steroid injection, number of surgical levels and revision surgery were the risk factors for CSFL. Effective prevention were the key to CSFL in lumbar surgery. Once appear, CSFL can also be effectively dealt without obvious adverse reactions after intraoperative effectively repair dural, head down, adequate drainage after operation, the high position, rehydration treatment, and other treatments.

Strong Correlation Between Superconductivity and Ferromagnetism in an Fe-Chalcogenide Superconductor.

The interplay among topology, superconductivity, and magnetism promises to bring a plethora of exotic and unintuitive behaviors in emergent quantum materials. The family of Fe-chalcogenide superconductors FeTexSe1-x are directly relevant in this context due to their intrinsic topological band structure, high-temperature superconductivity, and unconventional pairing symmetry. Despite enormous promise and expectation, the local magnetic properties of FeTexSe1-x remain largely unexplored, which prevents a comprehensive understanding of their underlying material properties. Exploiting nitrogen vacancy (NV) centers in diamond, here we report nanoscale quantum sensing and imaging of magnetic flux generated by exfoliated FeTexSe1-x flakes, demonstrating strong correlation between superconductivity and ferromagnetism in FeTexSe1-x. The coexistence of superconductivity and ferromagnetism in an established topological superconductor opens up new opportunities for exploring exotic spin and charge transport phenomena in quantum materials. The demonstrated coupling between NV centers and FeTexSe1-x may also find applications in developing hybrid architectures for next-generation, solid-state-based quantum information technologies.

Symptomatic postoperative discal pseudocyst following percutaneous endoscopic lumbar discectomy: A case report and review of the literature.

RATIONALE: Percutaneous endoscopic lumbar discectomy (PELD) is an effective treatment for lumbar disc herniation and postoperative discal pseudocyst (PDP) can rarely develop after PELD. PATIENT CONCERNS: A 30-year-old man experienced low back pain and pain in the right lower extremity for 1 month, which aggravated for 3 days. DIAGNOSES: Preoperative CT and MRI showed lumbar disc herniation at the L4/5 level. Then the patient underwent PELD under local anesthesia and his symptoms disappeared immediately after surgery. After 37 days of PELD, the patient complained of recurrent low back pain on the right side, and pain on the outer side of his lower leg. MR imaging revealed cystic mass with low signal on T1-weighted images (T1WI), and high signal on T2-weighted images (T2WI). The patient was diagnosed with a symptomatic PDP after PELD. INTERVENTIONS: Initially, the patient was treated with conservative treatment, including administration of aescin and mannitol by intravenous infusion, physical therapy, sacral canal injection. Then he underwent discography at L4/5 and ozone ablation under local anesthesia. OUTCOMES: The patient's condition improved significantly after 1 week of surgery and was discharged. One-year and 3-month follow-up revealed no recurrence of low back pain and leg pain. LESSONS: PDP is one of the rare complications of PELD, usually occurs in young patients. Patients with PDP have a low signal intensity on T1WI and high signal intensity on T2WI, which can be treated by conservative treatment, interventional therapy, and surgical treatment.

Moiré pattern of interference dislocations in condensate of indirect excitons.

Interference patterns provide direct measurement of coherent propagation of matter waves in quantum systems. Superfluidity in Bose-Einstein condensates of excitons can enable long-range ballistic exciton propagation and can lead to emerging long-scale interference patterns. Indirect excitons (IXs) are formed by electrons and holes in separated layers. The theory predicts that the reduced IX recombination enables IX superfluid propagation over macroscopic distances. Here, we present dislocation-like phase singularities in interference patterns produced by condensate of IXs. We analyze how exciton vortices and skyrmions should appear in the interference experiments and show that the observed interference dislocations are not associated with these phase defects. We show that the observed interference dislocations originate from the moiré effect in combined interference patterns of propagating condensate matter waves. The interference dislocations are formed by the IX matter waves ballistically propagating over macroscopic distances. The long-range ballistic IX propagation is the evidence for IX condensate superfluidity.

Time-reversal symmetry breaking in the Fe-chalcogenide superconductors.

Topological superconductivity has been sought in a variety of heterostructure systems, the interest being that a material displaying such a phenomenon could prove to be the ideal platform to support Majorana fermions, which in turn could be the basis for advanced qubit technologies. Recently, the high-Tc family of superconductors, FeTe1-xSex, have been shown to exhibit the property of topological superconductivity and further, evidence has been found for the presence of Majorana fermions. We have studied the interplay of topology, magnetism, and superconductivity in the FeTe1-x Se x family using high-resolution laser-based photoemission. At the bulk superconducting transition, a gap opens at the chemical potential as expected. However, a second gap is observed to open at the Dirac point in the topological surface state. The associated mass acquisition in the topological state points to time-reversal symmetry breaking, probably associated with the formation of ferromagnetism in the surface layer. The presence of intrinsic ferromagnetism combined with strong spin-orbit coupling provides an ideal platform for a range of exotic topological phenomena.

Report of four cases of crowned dens syndrome: Clinical presentation, CT findings and treatment.

The clinical manifestations of crowned dens syndrome (CDS) include acute neck pain and neck stiffness accompanied by restricted cervical range of motion. CDS is frequently misdiagnosed as meningitis, epidural abscess, rheumatoid arthritis, rheumatoid polymyalgia, giant cell arteritis, cervical spondylosis or metastatic bone tumor, and the incidence of CDS appears to be underestimated. The present study reported on four cases of CDS diagnosed by CT. They included one male and three females, aged from 67 to 78 years, and their major symptoms were acute neck pain and restricted cervical range of motion. Serum C-reactive protein levels and erythrocyte sedimentation rate were significantly increased in all cases. Cervical CT scan revealed calcified deposits surrounding the odontoid process in all cases. Non-steroidal anti-inflammatory drugs (NSAIDs) markedly reduced the levels of inflammatory indicators and rapidly relieved the symptoms. CT scan is considered the gold standard for CDS diagnosis, which may demonstrate calcification around the odontoid process. The patients' symptoms may be improved by treatment with NSAIDs.

Interaction Effects with Varying N in SU(N) Symmetric Fermion Lattice Systems.

The interaction effects in ultracold Fermi gases with SU(N) symmetry are studied nonperturbatively in half filled one-dimensional lattices by employing quantum Monte Carlo simulations. We find that, as N increases, weak and strong interacting systems are driven to a crossover region, but from opposite directions as a convergence of itinerancy and Mottness. In the weak interaction region, particles are nearly itinerant, and interparticle collisions are enhanced by N, resulting in the amplification of interaction effects. In contrast, in the strong coupling region, increasing N softens the Mott-insulating background through the enhanced virtual hopping processes. The crossover region exhibits nearly N-independent physical quantities, including the relative bandwidth, Fermi distribution, and the spin structure factor. The difference between even-N and odd-N systems is most prominent at small N's with strong interactions, since the odd case allows local real hopping with an energy scale much larger than the virtual one. The above effects can be experimentally tested in ultracold atom experiments with alkaline-earth(-like) fermions such as ^{87}Sr (^{173}Yb).

Synthetic Landau Levels and Spinor Vortex Matter on a Haldane Spherical Surface with a Magnetic Monopole.

We present a flexible scheme to realize exact flat Landau levels on curved spherical geometry in a system of spinful cold atoms. This is achieved by applying the Floquet engineering of a magnetic quadrupole field to create a synthetic monopole field in real space. The system can be exactly mapped to the electron-monopole system on a sphere, thus realizing Haldane's spherical geometry for fractional quantum Hall physics. This method works for either bosons or fermions. We investigate the ground-state vortex pattern for an s-wave interacting atomic condensate by mapping this system to the classical Thompson's problem. The distortion and stability of the vortex pattern are further studied in the presence of dipolar interaction. Our scheme is compatible with the current experimental setup, and may serve as a promising route of investigating quantum Hall physics and exotic spinor vortex matter on curved space.

Space-Time Crystal and Space-Time Group.

Crystal structures and the Bloch theorem play a fundamental role in condensed matter physics. We extend the static crystal to the dynamic "space-time" crystal characterized by the general intertwined space-time periodicities in D+1 dimensions, which include both the static crystal and the Floquet crystal as special cases. A new group structure dubbed a "space-time" group is constructed to describe the discrete symmetries of a space-time crystal. Compared to space and magnetic groups, the space-time group is augmented by "time-screw" rotations and "time-glide" reflections involving fractional translations along the time direction. A complete classification of the 13 space-time groups in one-plus-one dimensions (1+1D) is performed. The Kramers-type degeneracy can arise from the glide time-reversal symmetry without the half-integer spinor structure, which constrains the winding number patterns of spectral dispersions. In 2+1D, nonsymmorphic space-time symmetries enforce spectral degeneracies, leading to protected Floquet semimetal states. We provide a general framework for further studying topological properties of the (D+1)-dimensional space-time crystal.

Experimental observation of Bethe strings.

Almost a century ago, string states-complex bound states of magnetic excitations-were predicted to exist in one-dimensional quantum magnets. However, despite many theoretical studies, the experimental realization and identification of string states in a condensed-matter system have yet to be achieved. Here we use high-resolution terahertz spectroscopy to resolve string states in the antiferromagnetic Heisenberg-Ising chain SrCo2V2O8 in strong longitudinal magnetic fields. In the field-induced quantum-critical regime, we identify strings and fractional magnetic excitations that are accurately described by the Bethe ansatz. Close to quantum criticality, the string excitations govern the quantum spin dynamics, whereas the fractional excitations, which are dominant at low energies, reflect the antiferromagnetic quantum fluctuations. Today, Bethe's result is important not only in the field of quantum magnetism but also more broadly, including in the study of cold atoms and in string theory; hence, we anticipate that our work will shed light on the study of complex many-body systems in general.

Modified heterodyne efficiency for coherent laser communication in the presence of polarization aberrations.

Heterodyne efficiency is referred as a measure of the quality for the coherent laser communication. The heterodyne efficiency not only reflects the matching of phase and amplitude between the received signal and the local oscillator, but also reveals the polarization matching between the two beams. Different from the common heterodyne efficiency, a revised heterodyne efficiency is proposed by considering the polarization aberrations of optical system. Based on the Polar and Pauli-Zernike decomposition algorithms, the effects of polarization aberrations on the output polarization states are analyzed and shown graphically. The variations of the heterodyne efficiency are investigated by including the separate component of polarization aberrations in mixing of two perfectly matched Gaussian beams. Depending on the modified heterodyne efficiency, an off-axis optical system with a periscopic scanner is modeled and used to discuss the variations of the heterodyne efficiency. A further investigation for three different coatings is accomplished to verify the effects the varied polarization aberrations have on the heterodyne efficiency. The analysis indicates that the modified heterodyne efficiency not only can provide a comprehensive description of the coherent detection system, but also can be used to evaluate and minimize the polarization aberrations of optical system.