We theoretically demonstrate the feasibility of creating Bell states in multicomponent ultracold atomic gases by solely using the ability to control the interparticle interactions via Feshbach resonances. For this we consider two distinguishable impurities immersed in an atomic background cloud of a few bosons, with the entire system being confined in a one-dimensional harmonic trap. By analyzing the numerically obtained ground states we demonstrate that the two impurities can form spatially entangled bipolaron states due to mediated interactions from the bosonic bath. Our analysis is based on calculating the correlations between the two impurities in a two-mode basis, which is experimentally accessible by measuring the particle positions in the left or right sides of the trap. While interspecies interactions are crucial in order to create the strongly entangled impurity states, they can also inhibit correlations depending on the ordering of the impurities and three-body impurity-bath correlations. We show how these drawbacks can be mitigated by manipulating the properties of the bath, namely its size, mass, and intraspecies interactions, allowing one to create impurity Bell states over a wide range of impurity-impurity interactions.

Quantum generative models hold the promise of accelerating or improving machine learning tasks by leveraging the probabilistic nature of quantum states, but the successful optimization of these models remains a difficult challenge. To tackle this challenge, we present a new architecture for quantum generative modeling that combines insights from classical machine learning and quantum phases of matter. In particular, our model utilizes both many-body localized (MBL) dynamics and hidden units to improve the optimization of the model. We demonstrate the applicability of our model on a diverse set of classical and quantum tasks, including a toy version of MNIST handwritten digits, quantum data obtained from quantum many-body states, and nonlocal parity data. Our architecture and algorithm provide novel strategies of utilizing quantum many-body systems as learning resources and reveal a powerful connection between disorder, interaction, and learning in quantum many-body systems.

We study a supersolid in the context of a Gross-Pitaevskii theory with a nonlocal effective potential. We employ a homogenization technique which allows us to calculate the elastic moduli, supersolid fraction, and other state variables of the system. Our methodology is verified against numerical simulations of elastic deformations. We can also verify that the long-wavelength Goldstone modes that emerge from this technique agree with Bogoliubov theory. We find a thermodynamic anomaly that the supersolid does not obey the thermodynamic relation ${\partial P/\partial V|}_N=-n(\partial P/\partial N{|}_V)$, which we claim is a feature unique to supersolids.

We describe a general procedure for mapping arbitrary $n$-qubit states to two-dimensional (2D) vector fields. The mappings use complex rational function representations of individual qubits, producing classical vector field configurations that can be interpreted in terms of 2D inviscid fluid flows or electric fields. Elementary qubits are identified with localized defects in 2D harmonic vector fields, and multiqubit states find natural field representations via complex superpositions of vector field products. In particular, separable states appear as highly symmetric flow configurations, making them both dynamically and visually distinct from entangled states. The resulting real-space representations of entangled qubit states enable an intuitive visualization of their transformations under quantum logic operations. We demonstrate this for the quantum Fourier transform and the period finding process underlying Shor's algorithm, along with other quantum algorithms. Due to its generic construction, the mapping procedure suggests the possibility of extending concepts such as entanglement or entanglement entropy to classical continuum systems, and thus may help guide new experimental approaches to information storage and nonstandard computation.

Cavity optomechanics implements a unique platform where moving objects can be probed by quantum fields, either laser light or microwave signals. With a pump tone driving at a frequency above the cavity resonance, self-sustained oscillations can be triggered at large injected powers. These limit-cycle dynamics are particularly rich, presenting hysteretic behaviors, broad comb signals, and especially large motion amplitudes. All of these features can be exploited for both fundamental quantum research and engineering. Here we present low-temperature microwave experiments performed on a high-$Q$ cavity resonance capacitively coupled to the flexure of a beam resonator. We study the limit-cycle dynamics parameter space as a function of pump parameters (detuning, power). Unexpectedly, we find that in a region of this parameter space the microwave resonance is irremediably destroyed: Only a dramatic power reset can restore the dynamics to its original state. The phenomenon can be understood as an optical instability linked to the Kerr nonlinearity of the cavity. A theory supporting this claim is presented, reproducing almost quantitatively the measurement. This remarkable feature might be further optimized and represents a new resource for quantum microwave circuits.

Nowadays, materials science is moving towards the understanding and control of materials in nonequilibrium states by making use of perturbative techniques to investigate their dynamical responses. From this perspective, the use of ultrashort light pulses seems to be a relevant approach as it can selectively address different degrees of freedom in solid-state systems and more particularly electrons. Such a method can help to decipher the physical phenomena arising from electronic correlations and complements a more conventional methodology where the phase diagrams of materials are investigated at thermodynamical equilibrium. Here, we combine femtosecond optical spectroscopy and a high-pressure setup to monitor the ultrafast out-of-equilibrium photo response of a ${\mathrm{V}}_2{\mathrm{O}}_3$ thin film across the pressure driven insulator-to-metal transition. The experimental results demonstrate the possibility to use the spectroscopy of coherent phonons as a thermodynamical phase marker in ${\mathrm{V}}_2{\mathrm{O}}_3$ thin films. In addition, the frequency behavior of the ultrafast coherent phonon mode (${\mathrm{A}}_{1g}$ character) seems to reflect the manifestation of a strong coupling between the lattice and electronic degrees of freedom near first-order transition lines with a pronounced drop in frequency around the critical pressure.

Odd-diffusive systems are characterized by transverse responses and exhibit unconventional behaviors in interacting systems. To address the dynamical interparticle rearrangements in a minimal system, we here exactly solve the problem of two hard disklike interacting odd-diffusing particles. We calculate the probability density function (PDF) of the interacting particles in the Fourier-Laplace domain and find that oddness rotates all modes except the zeroth, resembling a mutual rolling of interacting odd particles. We show that only the first Fourier mode of the PDF, the polarization, enters the calculation of the force autocorrelation function (FACF) for generic systems with central-force interactions. An analysis of the polarization as a function of time reveals that the relative rotation angle between interacting particles overshoots before relaxation, thereby rationalizing the recently observed oscillating FACF in odd-diffusive systems [Kalz et al., Phys. Rev. Lett. 132, 057102 (2024)].

We find a set of exact solutions to Maxwell's equations in spacetime-varying materials, where the refractive index is constant, while the impedance exhibits effective motion, i.e., it is a function of $x-vt$. We find that waves copropagating with the modulation are not reflected within the material, while counterpropagating waves are continually reflected by the changing impedance. For a finite section of such a material, we find analogs of transmission resonances, where specially shaped eigenpulses enter without reflection. We also find that there is a strong asymmetry in reflection from the medium when the impedance modulation is small but rapid, the material reflecting strongly from one side and negligibly from the other. Unlike stationary media, the spectrum of the reflected wave can be significantly different from the incident one.

Implementing quantum error correction (QEC) protocols is a challenging task in today's era of noisy intermediate-scale quantum devices. We present quantum circuits for a universal, noise-adapted recovery map, often referred to as the Petz map, which is known to achieve close-to-optimal fidelity for arbitrary codes and noise channels. While two of our circuit constructions draw upon algebraic techniques such as isometric extension and block encoding, the third approach breaks down the recovery map into a sequence of two-outcome POVMs. In each of the three cases we improve upon the resource requirements that currently exist in the literature. Apart from Petz recovery circuits, we also present circuits that can directly estimate the fidelity between the encoded state and the recovered state. As a concrete example of our circuit constructions, we implement Petz recovery circuits corresponding to a four-qubit code that is tailor-made to correct for amplitude-damping noise. The efficacy of our noise-adapted recovery circuits is then demonstrated through ideal and noisy simulations on the IBM QasmSimulator.

Free electron beams and their quantum coupling with photons are attracting a rising interest due to the basic questions they address and the innovative technology these particles are involved in, such as microscopy, spectroscopy, and quantum computation. This work proposes spatially encoded coupling, where a dual-rail-like electron $\left(e^{-}\right)$ state is entangled to a dual-rail photonic qubit. Thus, it complements the leading current concept of the coupling, which links photonic Fock states with the $e^{-}$ energy. Importantly, we show that a spatial electron-photon pair can reach maximal entanglement and propose mutually unbiased bases for verifying the entanglement in a realistic experimental apparatus. Although the energy-level coupling of an $e^{-}$ beam with photonic excitations is well understood, we show that a naïve approach for extending such interaction from a single to a double path results in a retrocausal paradox. In the future, the atomic scale precision of electron microscopes can harness such position-encoded free-$e^{-}$ entangled qubits for novel quantum sensing and quantum transduction.

In present work, we present a couple-channel formalism for the description of tunneling time of a quantum particle through a composite compound with multiple energy levels or a complex structure that can be reduced to a quasi-one-dimensional multiple-channel system.

We present a quantum algorithm that analyzes time series data simulated by a quantum differential equation solver. The proposed algorithm is a quantum version of a dynamic mode decomposition algorithm used in diverse fields such as fluid dynamics, molecular dynamics, and epidemiology. Our quantum algorithm can also compute matrix eigenvalues and eigenvectors by analyzing the corresponding linear dynamical system. Our algorithm handles a broad range of matrices, particularly those with complex eigenvalues. The complexity of our quantum algorithm is $O(polylogN)$ for an $N$-dimensional system. This is an exponential speedup over known classical algorithms with at least $O\left(N\right)$ complexity. Thus, our quantum algorithm is expected to enable high-dimensional dynamical systems analysis and large matrix eigenvalue decomposition, intractable for classical computers.

The ability of eukaryotic cells to squeeze through constrictions is limited by the stiffness of their large and rigid nucleus. However, migrating cells are often able to overcome this limitation and pass through constrictions much smaller than their nucleus, a mechanism that is not yet understood. Here, we propose a methodological framework to observe, quantify, and model this nuclear translocation phenomenon through a data-driven approach using microfluidic devices where cells migrate through controlled narrow spaces of sizes comparable to the ones encountered in physiological situations. Stochastic force inference is applied to experimental nuclear trajectories and nuclear shape descriptors, resulting in equations that effectively describe the kinematics of this nuclear translocation phenomenon. By employing a model where the channel geometry is an explicit parameter and by training it over experimental data with different sizes of constrictions, we ensure that the resulting equations are predictive. Altogether, the approach developed here paves the way for a mechanistic and quantitative description of dynamical cell complexity during its motility.

Recent developments in the field of quantum machine learning have promoted the idea of incorporating physical symmetries in the structure of quantum circuits. A crucial milestone in this area is the realization of $S_n$-permutation equivariant quantum neural networks (QNNs) that are equivariant under permutations of input objects. In this paper, we focus on encoding the rotational symmetry of point cloud datasets into the QNN. The key insight of the approach is that all rotationally invariant functions with vector inputs are equivalent to a function with inputs of vector inner products. We provide a structure of the QNN that is exactly invariant to both rotations and permutations, with its efficacy demonstrated numerically in the problems of two-dimensional image classifications and identifying high-energy particle decays, produced by proton-proton collisions, with the $\mathrm{SO}(1,3)$ Lorentz symmetry.