We have directly loaded a cryogenic beam of molybdenum atoms into a magneto-optical trap. By chirping the detuning of the trapping lasers, we were able to enhance the number of atoms loaded into the trap by more than a factor of 2. We optimize the trapped samples for atom number, temperature, and lifetime by varying the laser-cooling parameters. The laser-cooled molybdenum atoms are subsequently transferred to a magnetic trap where we achieve vacuum-limited lifetimes of 100 ms. Comparison of magneto-optical trap and magnetic trap lifetimes allow us to extract partial decay rates of the $z{}^7{P}_4^{\text{o}}\to a{}^5{D}_4$ and $z{}^7{P}_4^{\text{o}}\to a{}^5{D}_3$ transitions. We also provide measurements of the isotope shifts for the $a{}^7{S}_3\to z{}^7{P}_4^{\text{o}}$ transition with up to four times better precision than previously reported. Finally, we discuss the prospect of applying the chriped magneto-optical trap to produce laser-cooled samples of MgF.

Progress toward room-temperature operation of terahertz quantum cascade lasers is limited by the lack of active regions that sustain efficient transport at elevated temperature. Designing such active regions requires predictive models that quantitatively connect microscopic transport and nonequilibrium energy evolution to device-level temperature characteristics. We propose a unified quadruple-coupled model that incorporates energy evolution via a time-dependent electron-temperature equation and self-consistently couples electron, phonon, and photon populations on a common timescale. The model captures the overheating-relaxation dynamics of the average electron temperature, stabilizing within a few picoseconds but delayed relative to the carrier population. The framework extends to above-threshold transport with radiative processes explicitly included and simulations show that their effect on electron temperature is smaller than that of electron-phonon coupling, thereby providing quantitative evidence that thermal relaxation is dominated by electron-phonon interactions. Across ten representative active regions, the predicted maximum operating temperatures show significant linear correlation with experiment ($r=0.909$), demonstrating the model's predictive capability for active-region temperature performance. These results identify electron energy dynamics as the key controlling factor at elevated temperature and provide a physics-based tool for designing high-temperature active regions toward near-room-temperature operation, with applicability to broader nonequilibrium semiconductor laser systems.

We present methodological advances in dynamic light scattering analysis through a multi-$\tau$ algorithm for the computation of both the intensity correlation function and the intensity structure function, combined with a semiempirical correction that systematically removes shot noise via conditional variance analysis. This unified framework enables consistent interpretation and direct comparison between correlation- and structure-function-based analyses. We validate the method across three experimental platforms: three-dimensional dynamic light scattering in polymer matrices, heterodyne dynamic light scattering in dense silica suspensions, and diffusing wave spectroscopy in turbid latex colloids. In all cases, the intensity structure function outperforms the correlation function. In three-dimensional dynamic light scattering, it yields mean-squared errors in model fits 5–$10\%$ lower; in heterodyne light scattering, it reduces the standard error at short and intermediate lag times when averaging over multiple datasets; and in diffusing wave spectroscopy, it exhibits greater robustness to variations in instrumental parameters such as the coherence factor. These results establish the intensity structure function, enhanced by precise noise correction and efficient computation, as a stable, reliable tool for analyzing heterogeneous, nonergodic, and complex fluids. The approach sets a benchmark for extracting dynamic properties from photon time series and expands the possibilities for accurate, consistent analysis in advanced light scattering studies.

Response functions are a key quantity to describe the near-equilibrium dynamics of strongly interacting many-body systems. Recent techniques that attempt to overcome the challenges of calculating these ab initio have employed expansions in terms of orthogonal polynomials. We employ a neural network prediction algorithm to reconstruct a response function $S\left(\omega \right)$ defined over a range in frequencies $\omega$. We represent the calculated response function as a truncated Chebyshev series whose coefficients can be optimized to reduce the representation error. We compare the quality of response functions obtained using coefficients calculated using a neural network (NN) algorithm with those computed using the Gaussian integral transform (GIT) method. In the regime where only a small number of terms in the Chebyshev series are retained, we find that the NN scheme outperforms the GIT method.

Quantum error correction is essential for fault-tolerant quantum computing. However, standard methods relying on active measurements may introduce additional errors. Autonomous quantum error correction (AQEC) circumvents this by utilizing engineered dissipation and drives in bosonic systems, but identifying practical encoding remains challenging due to stringent Knill-Laflamme conditions. In this work, we utilize curriculum learning enabled deep reinforcement learning to discover bosonic codes under an approximate AQEC framework to resist both single-photon and double-photon losses. We present an analytical solution of the master equation under approximation conditions, which can significantly accelerate the training process of reinforcement learning. The agent first identifies an encoded subspace surpassing the breakeven point through rapid exploration within a constrained evolutionary time frame, then strategically fine-tunes its policy to sustain this performance advantage over extended temporal horizons. We find that the two-phase trained agent can discover the optimal set of codewords, i.e., the Fock states $|4\rangle$ and $|7\rangle$, considering the effect of both single-photon and double-photon loss. We identify that the discovered code surpasses the breakeven threshold over a longer evolution time and achieves state-of-the-art performance. We also analyze the robustness of the code against phase damping and amplitude damping noise. Our work highlights the potential of curriculum learning enabled deep reinforcement learning in discovering the optimal quantum error correction code especially in early fault-tolerant quantum systems.

Two-dimensional planar ion crystals in a Penning trap are a platform for quantum information science experiments. However, the low-frequency planar modes of these crystals are not efficiently cooled by laser cooling, which can limit the utility of the drumhead modes for quantum information processing. Recently, it has been shown that nonlinear mode coupling can enhance the cooling of the low-frequency planar modes. Here, we demonstrate in numerical simulations that this coupling can be dynamically tuned by adiabatically changing the rotation frequency of the ion crystal during experiments. Furthermore, we show that this technique can, in addition, produce lower temperatures for the low-frequency planar modes via an adiabatic cooling process. This result allows cooling of the planar modes to sub-millikelvin temperatures, resulting in improved spectral resolution of the drumhead modes at experimentally relevant rotation frequencies, which is crucial for quantum information processing applications.

Nonrelativistic anyons in one dimension possess generalized exchange statistics in which the exchange of two identical anyons generates a phase that is governed by the spatial ordering of the particles and the statistical parameter $\alpha$. Working in the continuum, we demonstrate the existence of two distinct types of one-dimensional (1D) anyons, namely, bosonic anyons and fermionic anyons. We identify a many-body Hamiltonian with additive two-body zero-range interactions that supports bosonic and fermionic anyon eigenstates, which are, for arbitrary interaction strength, related through a generalized bosonic-anyon–fermionic-anyon mapping, an extension of the celebrated Bose-Fermi mapping for zero-range interacting 1D systems. The momentum distributions of bosonic and fermionic anyons are distinct: while both feature $k^{-2}$ and $k^{-3}$ tails, the associated prefactors differ. Our work reveals intricate connections between the generalized exchange statistics, the universal two- and three-body Tan contacts of systems consisting of $N$ identical particles, and the emergence of statistics-induced chiral symmetry breaking.

While elementary particles obey either bosonic or fermionic exchange statistics, generalized exchange statistics that interpolate between bosons and fermions—applicable to quasiparticles—constitute an intriguing topic from both the fundamental and practical points of view. This work develops a scattering framework for two identical one-dimensional (1D) bosonic anyons and two identical 1D fermionic anyons with zero-range contact interactions. The two-body system with zero-range interactions, in both free space and under external confinement, is used to illustrate the recently proposed bosonic-anyon—fermionic-anyon mapping (R. Hidalgo-Sacoto et al., Phys. Rev. A 112, 063309 (2025)), which connects the eigenstates of bosonic anyons to those of fermionic anyons and vice versa. Performing explicit calculations for two-particle systems, the momentum distributions and the off-diagonal correlations of the single-particle density matrix for bosonic anyons and fermionic anyons are confirmed to be distinct. We also confirm the previously derived asymptotic coefficients of the momentum distribution tail at orders $k^{-2}$ and $k^{-3}$ for two harmonically confined anyons. Nonuniversal contributions at order $k^{-4}$ are discussed.

We investigate the threshold behavior of lasers under various modeling approaches, considering different numbers of nonlasing cavity modes and analyzing the effects of radiation-matter coupling strength, cavity lifetime, and quantum-dot properties. Thermal and electron-electron decoherence are incorporated as phenomenological relaxation processes, in line with established practices. Both spectrally uniform and polydisperse quantum dots are examined. For the former, we observe strong agreement across modeling approaches: the qualitative behavior remains consistent, with threshold pump values showing quantitative shifts depending on the specific model. In the case of polydisperse quantum dots, leading to inhomogeneous broadening, this picture is reaffirmed—each model type exhibits similar qualitative trends, while threshold variations arise due to the stochastic distribution of emitter transition frequencies. Our results confirm that models that assume homogeneous quantum dots are suitable for comparison with experimental data and that inhomogeneous effects can be directly captured using our framework when required.

We investigate the improvement of anti-Stokes laser cooling of a ${\mathrm{Yb}}^{3+}$:YLF nanocrystal in a Fabry-Pérot microcavity via the Purcell effect. Our analysis accounts for both the enhancement of emission lines resonant with the cavity transmission and the suppression of off-resonance emissions. Using a quantum-mechanical framework, we modeled the ${\mathrm{Yb}}^{3+}$ ions in a ${\mathrm{YLiF}}_4$ matrix and the laser system to calculate the minimum achievable temperature and cooling efficiency, incorporating cavity-induced modifications to experimental data on the emission cross section. Our results indicate that for temperatures below 100 K, the cooling efficiency $\eta$ is consistently enhanced, and the minimum achievable temperature is reduced comfortably below the current limits. We also show how the inclusion of Purcell inhibition effects can lead to improvements in the cooling efficiency ranging from 25% to 65% with respect to the case when only Purcell enhancement is considered.

The ability to harness the ubiquitous dissipation in realistic quantum systems holds great promise for developing advanced quantum technologies. In particular, the presence of dissipation violates the fundamental premise of Hermiticity and results in the non-Hermitian singularities associated with coalesced eigenstates in parameter space known as exceptional points (EPs), providing a new strategy to manipulate quantum states in both dynamical evolution and stationary limit. In this work, we show that for a microcavity supporting chiral EPs, light-matter interaction between the cavity photons and a quantum emitter can be flexibly switched from coherent to fully dissipative by tuning the phase factor of a complex coupling rate, an additional degree of freedom offered by the chiral EPs of a microcavity. The tunable coherent and dissipative light-matter interactions are evidenced by the distinguishing quantum dynamics and optical spectra, where the dispersion of a coupled quantum system changes from level repulsion to level attraction. While dissipation is generally considered fatal for quantum effects and should be suppressed, here we find that the EP-enabled dissipative light-matter interaction shows a unique advantage in achieving high-efficiency single-photon emission in a weak-coupling regime through the non-Hermitian photon blockade, which originates from the anharmonicity in the losses instead of in the eigenenergy levels for the conventional photon blockade (CPB). A giant enhancement of more than 5 orders of magnitude is found for both photon correlations and intensity compared to that of CPB in coherent light-matter interaction. We expect our work to enrich the understanding of light-matter interaction in open photonic resonators and provide insight into the manipulation of quantum states and quantum correlations in a wide variety of quantum systems by utilizing the non-Hermicity of electromagnetic environments.

We revisit the Jaynes-Cummings model as an autonomous thermodynamic machine, where a qubit is driven by a cavity containing initially a large coherent field. Our analysis reveals a transition between the expected behavior of ideal-work source of the cavity at short times, and a long-time dynamics where the cavity autonomously measures the qubit and exerts a result-dependent drive. This autonomous feedback then purifies the qubit irrespective of its initial state. We show that the cavity functions thermodynamically as an autonomous Maxwell demon, trading mutual information for cooling power.

Interpretable machine learning is rapidly becoming a crucial tool for scientific discovery. Among existing approaches, variational autoencoders (VAEs) have shown promise in extracting the hidden physical features of some input data, with no supervision nor prior knowledge of the system at study. Yet the ability of VAEs to create meaningful, interpretable representations relies on their accurate approximation of the underlying probability distribution of their input. When dealing with quantum data, VAEs must hence account for its intrinsic randomness and complex correlations. While VAEs have been previously applied to quantum data, they have often neglected its probabilistic nature, hindering the extraction of meaningful physical descriptors. Here we demonstrate that two key modifications enable VAEs to learn physically meaningful latent representations: a decoder capable of faithfully reproducing the probability distributions of quantum states and a probabilistic loss tailored to this task. Using benchmark quantum spin models, we identify regimes where standard methods fail while the representations learned by our approach remain meaningful and interpretable. Applied to experimental data from Rydberg atom arrays, the model autonomously uncovers the phase structure without access to prior labels, Hamiltonian details, or knowledge of relevant order parameters, highlighting its potential as an unsupervised and interpretable tool for the study of quantum systems.

We propose experimentally feasible separability criteria for bipartite systems based on local symmetric measurements. Through detailed examples, we demonstrate that our criteria can detect entanglement more effectively compared to existing counterparts. Furthermore, we demonstrate the potential for our results to be generalized to general multipartite systems.

Optical nuclear electric resonance (ONER) was recently proposed as a fast and robust single-qubit gate mechanism in ${}^{87}\mathrm{Sr}$. Here, we demonstrate through numerical simulations that ONER can be extended to single-qudit control, addressing multiple one-level hyperfine transitions within the ten-dimensional nuclear-spin manifold. We identify suitable operating regimes and show that ONER enables high-fidelity spin manipulations, with simulated π-gate fidelities exceeding 99.9%, while maintaining coherence under realistic parameter fluctuations. These results establish a proof of principle for optical qudit control in ${}^{87}\mathrm{Sr}$ and delineate practical parameter ranges for future experiments, highlighting ONER as a promising pathway toward high-dimensional quantum information processing.

Reliable and robust control lies at the core of implementing quantum information processing with nitrogen-vacancy (NV) centers in diamond. However, control pulses inevitably introduce multiple errors, leading to decoherence and hindering scalable applications. Here, we experimentally report an experiment-friendly multiple-noise-resilient nonadiabatic geometric quantum gate (MNR-NGQG) that can significantly improve the conventional dynamical gate in both robustness and coherence. Notably, even when the detuning fluctuation range is comparable to the maximum Rabi frequency, the single-qubit gate performance of the MNR-NGQG remains almost unchanged. Additionally, the coherence decay time of the electron spin under MNR-NGQG driving is significantly extended to 690 $\pm$ 30 $\mu \mathrm{s}$, 3.5 times longer than that of the naive dynamical counterpart. As a result, the fidelity of single-qubit gates reaches 0.9992(1), as characterized by quantum process tomography. With its experimentally feasible design and relaxed hardware requirements, our work offers a solid paradigm for achieving high-fidelity quantum control in the NV center system, paving the way for practical applications in quantum information science.

Power broadening refers to the widening of the spectral line profile in a two-state quantum transition as the strength of the driving field increases. This phenomenon commonly arises in continuous-wave driving when the radiation field's intensity exceeds the transition's saturation intensity and it has been extensively studied in spectroscopy. For pulsed-field excitation, the spectral response of the quantum system may differ significantly: while a rectangular-shaped pulse leads to a linear power broadening, pulses with smooth shapes show significantly reduced power broadening, for instance, logarithmic for the Gaussian shape and none for the hyperbolic-secant shape. Recently [Phys. Rev. Lett. 132, 020802 (2024)], in a dramatic paradigm shift, we have demonstrated experimentally that for Lorentzian-shaped pulses, the opposite effect—power narrowing—takes place: the width of the spectral profile decreases when the driving pulse amplitude increases, with a narrowing factor of as much as 10 observed. While in high-resolution spectroscopy the push is for eliminating or even inverting the power broadening, there are applications where it is used to an advantage for it facilitates off-resonance excitation. Here, we present a number of shaped pulses that exhibit power broadening much greater than that of the rectangular pulse of the same pulse area. They are grouped in two families of pulse shapes. In particular, in regard to the width of the second Rabi oscillation maximum, the quadratic pulse family shows a spectral increase by a factor of 3.3 whereas the power-law pulse family exhibits an increase by a factor of more than 3.5.

We study high harmonic generation with vortex beams beyond the dipole approximation. To do so, we employ the full minimal coupling approach to account for multipolar coupling without truncation and describe the full spatio-temporal properties of the electromagnetic field. This allows us to investigate the beyond-dipole deviations in electron trajectories and the harmonic spectra, where the influence of the orbital angular momentum contains both magnetic and quadrupolar effects. We show that when the system is driven by plane-wave light, nonlinear dipole oscillations occur along both the polarization and propagation directions, consistent with previous findings. In contrast, vortex beams also generate nonlinear dipole oscillations in the direction perpendicular to both the polarization and propagation of the incoming field. We identify the effects of the resulting symmetry breaking due to beyond-dipole corrections, which are especially visible in even harmonics.

We analytically investigated the dynamical quantum phase transitions in the Bose-Hubbard model using the Loschmidt echo as an observable, revealing that after a quench, the global Loschmidt echo exhibits cusp singularities with a logarithmically divergent rate function near criticality and a critical exponent of zero. Through extensive calculations across various system sizes and initial states, we have demonstrated that in the strongly interacting regime, the critical singularity of dynamical quantum phase transitions exhibits consistency across different model details and initial product states (charge-density wave states). Moreover, we find that modifying the harmonic potential well not only preserves the phase transition but also enables precise control over the transition timing.