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Topology, geometry, and gauge fields play key roles in quantum physics as exemplified by fundamental phenomena such as the Aharonov–Bohm effect, the integer quantum Hall effect, the spin Hall, and topological insulators. The concept of topological protection has also become a salient ingredient in many schemes for quantum information processing and fault-tolerant quantum computation. The physical properties of such systems crucially depend on the symmetry group of the underlying holonomy. Here, we study a laser-cooled gas of strontium atoms coupled to laser fields through a four-level resonant tripod scheme. By cycling the relative phases of the tripod beams, we realize non-Abelian SU(2) geometrical transformations acting on the dark states of the system and demonstrate their non-Abelian character. We also reveal how the gauge field imprinted on the atoms impact their internal state dynamics. It leads to a thermometry method based on the interferometric displacement of atoms in the tripod beams. The symmetry group and geometric phase of a system are responsible for many quantum properties related to non-trivial topology. Here the authors show non-Abelian geometric phase in laser-coupled ultracold strontium atoms by using a tripod scheme.

By analyzing the parameters of electronic transitions, we show how bosonic Sr atoms in planar optical lattices can be engineered to exhibit optical magnetism and other higher-order electromagnetic multipoles that can be harnessed for wavefront control of incident light. Resonant \\(\\lambda\\simeq 2.6\\mu\\)m light for the \\(^3D_1\\rightarrow {^3}P_0\\) transition mediates cooperative interactions between the atoms while the atoms are trapped in a deeply subwavelength optical lattice. The atoms then exhibit collective excitation eigenmodes, e.g., with a strong cooperative magnetic response at optical frequencies, despite individual atoms having negligible coupling to the magnetic component of light. We provide a detailed scheme to utilize excitations of such cooperative modes consisting of arrays of electromagnetic multipoles to form an atomic Huygens' surface, with complete \\(2\\pi\\) phase control of transmitted light and almost no reflection, allowing nearly arbitrary wavefront shaping. In the numerical examples, this is achieved by controlling the atomic level shifts of Sr with off-resonant \\({^3P}_J\\rightarrow {^3D}_1\\) transitions, which results in a simultaneous excitation of arrays of electric dipoles and electric quadrupoles or magnetic dipoles. We demonstrate the wavefront engineering for a Sr array by realizing the steering of an incident beam and generation of a baby-Skyrmion texture in the transmitted light via a topologically nontrivial transition of a Gaussian beam to a Poincar\\'{e} beam, which contains all possible polarizations in a single cross-section.

The objective of this study was to assess the efficacy and safety of liposomal heparin spray—a new formula of topical heparin delivery. This was a randomized, multicenter, controlled open clinical trial with 2 parallel groups. Forty-six outpatients with clinical signs of superficial venous thrombosis (SVT) were treated with either topical liposomal heparin spraygel (LHSG) (Lipohep Forte Spraygel, 4 puffs of 458 IU tid (n=22) or with low-molecular-weight heparin (LMWH) (Clexane 40 mg once a day (n=24), administered subcutaneously (sc). Main outcome measures were efficacy parameters (improvement of local symptoms—pain control and planimetric evaluation of erythema size, duplex Doppler assessment of thrombus regression) and safety parameters (documentation of adverse events, with particular reference to deep vein thrombosis [DVT] by duplex sonography, and patients’ and investigators’ assessment of drug tolerance). Patients’ and investigators’ subjective assessment of efficacy of treatment and change in basic biochemical parameters were defined as secondary outcome measures. Statistical analysis was performed with use of Wilcoxon test, Mann-Whitney U-test and Chi-square test. Regression of SVT-related symptoms, including pain, erythema, and thrombus presence, was shown as comparable in LHSG and LMWH groups. These results were corroborated by efficacy assessment by investigators and patients. Three cases of deep venous thrombosis in heparin spraygel and 1 in heparin sc group were reported. No significant adverse reactions were observed in the spraygel group, but 1 serious allergic reaction was observed in the LMWH group. Tolerance of new formula heparin was assessed as good. Heparin spraygel—a new topical mode of heparin application, seems a promising method of heparin delivery. This initial study has demonstrated comparable efficacy and safety of LHSG and LMWH in local treatment of SVT. These findings should be confirmed by further extensive study that will reach appropriate statistical power to support such conclusion, for despite heparin treatment, significant risk of DVT was demonstrated in both groups.

We present a novel cold strontium atom source designed for quantum sensors. We optimized the deceleration process to capture a large velocity class of atoms emitted from an oven and achieved a compact and low-power setup capable of generating a high atomic flux. Our approach involves velocity-dependent transverse capture of atoms using a two-dimensional magneto-optical trap. To enhance the atomic flux, we employ tailored magnetic fields that minimize radial beam expansion and incorporate a cascaded Zeeman-slowing configuration utilizing two optical frequencies. The performance is comparable to that of conventional Zeeman slower sources, and the scheme is applicable to other atomic species. Our results represent a significant advancement towards the deployment of portable and, possibly, space-based cold atom sensors.

In 1949, Ramsey's method of separated oscillating fields was elaborated boosting over many decades metrological performances of atomic clocks and becoming the standard technique for very high precision spectroscopic measurements. A generalization of this interferometric method is presented replacing the two single coherent excitations by arbitrary composite laser pulses. The rotation of the state vector of a two-level system under the effect of a single pulse is described using the Pauli matrices basis of the SU(2) group. It is then generalized to multiple excitation pulses by a recursive Euler-Rodrigues-Gibbs algorithm describing a composition of rotations with different rotation axes. A general analytical formula for the phase-shift associated with the clock's interferometric signal is derived. As illustrations, hyper-clocks based on three-pulse and five-pulse interrogation protocols are studied and shown to exhibit nonlinear cubic and quintic sensitivities to residual probe-induced light-shifts. The presented formalism is well suited to optimize composite phase-shifts produced by tailored quantum algorithms in order to design a new generation of optical frequency standards and robust engineering control of atomic interferences in AMO physics with cold matter and anti-matter.

A new class of atomic interferences using ultra-narrow optical transitions are pushing quantum engineering control to a very high level of precision for a next generation of sensors and quantum gate operations. In such context, we propose a new quantum engineering approach to Ramsey-Bordé interferometry introducing multiple composite laser pulses with tailored pulse duration, Rabi field amplitude, frequency detuning and laser phase-step. We explore quantum metrology with hyper-Ramsey and hyper-Hahn-Ramsey clocks below the \\(10^-18\\) level of fractional accuracy by a fine tuning control of light excitation parameters leading to spinor interferences protected against light-shift coupled to laser-probe field variation. We review cooperative composite pulse protocols to generate robust Ramsey-Bordé, Mach-Zehnder and double-loop atomic sensors shielded against measurement distortion related to Doppler-shifts and light-shifts coupled to pulse area errors. Fault-tolerant auto-balanced hyper-interferometers are introduced eliminating several technical laser pulse defects that can occur during the entire probing interrogation protocol. Quantum sensors with composite pulses and ultra-cold atomic sources should offer a new level of high accuracy in detection of acceleration and rotation inducing phase-shifts, a strong improvement in tests of fundamental physics with hyper-clocks while paving the way to a new conception of atomic interferometers tracking space-time gravitational waves with a very high sensitivity.

We measure the resonant forward scattering of light by a highly saturated atomic medium through the flashes emitted immediately after an abrupt extinction of the probe beam. The experiment is done in a dilute regime where the phenomena are well captured using the independent scattering approximation. Comparing our measurements to a model based on Maxwell-Bloch equations, our experimental results are consistent with contributions from only the elastic component, whereas the attenuation of the coherent transmission power is linked to the elastic and inelastic scatterings. In the large saturation regime and at the vicinity of the atomic resonance, we derive an asymptotic expression relating the elastic scattering power to the forward-scattered power.

A novel form of quantum control is proposed by applying twisted-light also known as optical vortex beams to drive ultra-narrow atomic transitions in neutral Ca, Mg, Yb, Sr, Hg and Cd bosonic isotopes. This innovative all-optical spectroscopic method introduces spatially tailored electric and magnetic fields to fully rewrite atomic selection rules reducing simultaneously probe-induced frequency-shifts and additional action of external ac and dc field distortions. A twisted-light focused probe beam produces strong longitudinal electric and magnetic fields along the laser propagation axis which opens the 1S0-3P0 doubly forbidden clock transition with a high E1M1 two-photon excitation rate. This long-lived clock transition is thus immune to nonscalar electromagnetic perturbations. Zeeman components of the M2 magnetic quadrupole 1S0-3P2 transition considered for quantum computation and simulation are now selectively driven by transverse or longitudinal field gradients with vanishing electric fields. These field gradients are manipulated by the mutual action of orbital and spin angular momentum of the light beam and are used in presence of tunable vector and tensor polarizabilities. A combination of these two different twisted-light induced clock transitions within a single quantum system, at the same magic wavelength and in presence of a common thermal environment significantly reduces systematic uncertainties. Furthermore, it generates an optical synthetic frequency which efficiently limits the blackbody radiation shift and its variations at room temperature. Engineering light-matter interaction by optical vortices will benefit to experimental atomic and molecular platforms targeting an optimal coherent control of quantum states, reliant quantum simulation, novel approach to atomic interferometry and precision tests of fundamental theories in physics and high-accuracy optical metrology.

A new generation of atomic sensors using ultra-narrow optical clock transitions and composite pulses are pushing quantum engineering control to a very high level of precision for applied and fundamental physics. Here, we propose a new version of Ramsey-Bordé interferometry introducing arbitrary composite laser pulses with tailored pulse duration, Rabi field, detuning and phase-steps. We explore quantum metrology below the \\(10^{-18}\\) level of fractional accuracy by a fine tuning control of light excitation parameters protecting ultra-narrow optical clock transitions against residual light-shift coupled to laser-probe field fluctuation. We present, for the first time, new developments for robust hyper Ramsey-Bordé and Mach-Zehnder interferometers, where we protect wavepacket interferences against distortion on frequency or phase measurement related to residual Doppler effects and light-shifts coupled to a pulse area error. Quantum matter-wave sensors with composite pulses and ultra-cold sources will offer detection of inertial effects inducing phase-shifts with better accuracy, to generate hyper-robust optical clocks and improving tests of fundamental physics, to realize a new class of atomic interferometers tracking space-time gravitational waves with a very high sensitivity.

We propose a quantum memory protocol where a input light field can be stored onto and released from a single ground state atomic ensemble by controlling dynamically the strength of an external static and homogeneous field. The technique relies on the adiabatic following of a polaritonic excitation onto a state for which the forward collective radiative emission is forbidden. The resemblance with the archetypal Electromagnetically-Induced-Transparency (EIT) is only formal because no ground state coherence based slow-light propagation is considered here. As compared to the other grand category of protocols derived from the photon-echo technique, our approach only involves a homogeneous static field. We discuss two physical situations where the effect can be observed, and show that in the limit where the excited state lifetime is longer than the storage time, the protocols are perfectly efficient and noise-free. We compare the technique to other quantum memories, and propose atomic systems where the experiment can be realized.