We demonstrate deterministic preparation of arbitrary two-component product states of fermionic ^{6}Li atoms in an 8×8 optical tweezer array, achieving motional ground-state fidelities above 98.5%. Leveraging the large differential magnetic moments for spin-resolution, with parallelized site- and number-resolved control, our approach addresses key challenges for low-entropy quantum state engineering. Combined with high-fidelity spin-, site-, and density-resolved readout within a single 20 μs exposure, and 3s experimental cycles, these advances establish a fast, scalable, and programmable architecture for fermionic quantum simulation.

Non-Hermitian quantum systems, governed by nonunitary evolution, offer powerful tools for manipulating quantum states through engineered loss. A prime example is coherent absorption, where quantum states undergo phase-dependent partial or complete absorption in a lossy medium. Here, we demonstrate a fully programmable implementation of nonunitary transformations that emulate coherent absorption of quantum light using a programmable integrated linear photonic circuit, with loss introduced via coupling to an ancilla mode. Probing the circuit with a single-photon dual-rail state reveals phase-controlled coherent tunability between perfect transmission and perfect absorption. A two-photon NOON-state input, by contrast, exhibits switching between deterministic single-photon absorption and probabilistic two-photon absorption. Across a broad range of input phases and circuit configurations, we observe nonclassical effects including anti-coalescence and bunching, together with continuous and coherent tuning of output Fock-state probability amplitudes. Classical Fisher information analysis reveals phase sensitivity peaks of 1 for single-photon states and 3.4 for NOON states, exceeding the shot-noise limit of 2 and approaching the Heisenberg limit of 4 for two-photon states. The experiment integrates quantum state generation, programmable photonic circuitry, and photon-number-resolving detection, establishing ancilla-assisted circuits as powerful platforms for programmable quantum state engineering, filtering, multiplexed sensing, and nonunitary quantum simulation.

We address that a single-band tight-binding Hamiltonian defined on a self-similar corral substrate can give rise to a set of non-diffusive localized modes that follow the same hierarchical distribution as the lattice. The spatial extent of quantum prison containing a cluster of atomic sites is dependent on the generation of fractal structure. Apart from the quantum imprisonment of the excitation, a magnetic flux threading each elementary plaquette is shown to destroy the boundedness and generate an absolutely continuous sub-band populated by resonant eigenfunctions. Flux induced engineering of quantum states is corroborated through the evaluation of inverse participation ratio and quantum transport. The robustness of the extended states has been checked in presence of diagonal disorder and off-diagonal anisotropy. The conducting region is found to be insensitive against minimal parametric modulation. Flux modulated single-particle mobility edge is characterized through multifractal analysis. Quantum interference is the essential issue, reported here, that manipulates the kinematics of the excitation and this is manifested by the calculation of persistent current.

Photon condensation in semiconductor microcavities is a transformative technique for engineering quantum states of light at room temperature by tailoring strong but incoherent light-matter interactions. While continuous-wave and electrical pumping offer exceptional prospects for miniaturized quantum photonic technologies, harnessing these requires conceptual advances in understanding non-equilibrium light-matter dynamics in semiconductors. We resolve this challenge through anab initioquantum kinetic theory capturing how Coulomb interactions of optically excited carriers and phonon scattering mediate photon thermalization and condensation in semiconductors. Our microscopic model shows that at high carrier densities, thermalization is dominated by carrier-carrier Coulomb scattering, in clear contrast to the rovibrational relaxation that governs dye-based photon condensates. The theory predicts a rich nonequilibrium phase diagram with thermal, Bose-condensed, multimode, and lasing phases, quantitatively in agreement with recent experiments. Crucially, we identify how cavity detuning controls transitions between equilibrium and gain-dominated regimes, enabling tailored design of coherent light sources. This work thus provides the foundation for semiconductor-based quantum photonic devices operating beyond conventional laser paradigms.

Abstract The discrimination of quantum states is a central problem in quantum information science and technology. Meanwhile, partial post-selection has emerged as a valuable tool for quantum state engineering. In this work, we bring these two areas together and ask whether partial measurements can enhance the discrimination performance between two unknown and non-orthogonal pure states. Our framework is general: the two unknown states interact with the same environment—set in a pure state—via an arbitrary unitary transformation. A measurement is then performed on one of the output modes (i.e. a partial measurement), modeled by an arbitrary positive operator-valued measure (POVM). We then allow classical communication to inform the unmeasured mode of the outcome of the partial measurement, which is subsequently measured by a POVM that is optimal in the sense that the discrimination probability of error is minimized. The two POVMs act locally and classical information is exchanged between the two modes, representing a single-round (feed-forward) form of local operations with classical communication. Under these considerations, we first show that, as expected, the minimum error probability, averaged over all possible conditional states, cannot be reduced below the minimum error probability of discriminating the original input states. Then, we devise a generic setup produces specific examples where the conditional discrimination can achieve strictly lower error probabilities than the original optimal measurement, illustrating that while post-selection does not improve the average performance, it can enable better discrimination in certain post-selected ensembles.

Abstract The practical value of non-Gaussian states for quantum computation, metrology, and networking is currently limited by the intrinsically low success rates of conventional generation methods like photon addition and subtraction. We introduce a scalable protocol that overcomes this bottleneck using postselected von Neumann measurements beyond the weak-coupling regime. Applied to standard Gaussian inputs, our method efficiently generates a suite of critical resources—including large-amplitude Schrödinger cat states, Gottesman–Kitaev–Preskill-like states, and two-mode entangled states—with considerably higher success probabilities. Quantitative analysis of Wigner negativity and entanglement confirms their high quality. This work establishes postselected von Neumann measurement as a general and scalable principle for quantum resource generation, moving beyond a fundamental limitation in quantum state engineering.

In this work, we explore a tunable scheme for achieving precise two-dimensional (2D) atomic localization in a four-level tripod atomic system. The system is driven by two control fields with orbital angular momentum and a weak probe field. By varying the azimuthal quantum numbers, spatial phase shifts, and atomic decay rates, we demonstrate controlled manipulation of atomic localization with high spatial precision. The interaction of structured light fields with the atomic system generates interference patterns that result in sharp localization peaks in the 2D plane. The study investigates the effects of varying the control parameters, such as phase shifts and decay rates, on the number, spacing, and sharpness of these localization peaks. Notably, optimized parameters lead to the formation of a single, highly localized transmission peak, enabling subwavelength spatial resolution. Our results have significant implications for applications in atom lithography, precision spectroscopy, and quantum state engineering, offering a flexible method for precise control of atomic positions in quantum systems.

We introduce a protocol for generating non-Gaussian (nG) states via postselected weak measurement. The scheme involves injecting an arbitrary quantum state and a single photon into the signal and idler ports of an interferometer with a third-order nonlinear medium. An nG state is conditionally produced at the signal output, heralded by single-photon detection in an idler output channel. The protocol exploits a weak cross-Kerr interaction, with effective single-photon nonlinearity enhanced by weak-value amplification. By tuning the weak value of the idler photon number operator within experimentally feasible parameters, diverse nG states can be generated with high fidelity. Specific examples include photon-added coherent states, displaced and squeezed number states, and intermediate nG states from coherent and squeezed vacuum inputs. Furthermore, the protocol enables enhancement of non-Gaussianity and enlargement of Schrödinger cat (SC) states when ideal SC states are used as input. Our results provide an alternative route for conditional generation of tunable nG states, with potential applications in quantum information processing and state engineering.

The interfacial electronic properties of complex oxides are governed by a delicate balance between charge transfer, lattice distortions, and electronic correlations, posing a key challenge for controlled tunability in materials research. Here, we demonstrate that proton implantation serves as a precise tool for modulating interfacial transport in SrTiO3-based heterostructures. By introducing protons into the SrTiO3 substrate beneath an amorphous (La,Sr)(Al,Ta)O3 capping layer, we uncover competition between disorder and charge doping induced by implantation. At low implantation fluences below 1 × 1015 protons per cm2 (1E15), the charge doping dominates, leading to an increase in carrier density and mobility, analogous to electrostatic gating effects. This enables the emergence of quantum transport oscillations at low temperature. Conversely, at higher fluences (above 1E15), disorder scattering prevails, suppressing carrier mobility and inducing an insulating state. The nonmonotonic evolution of transport with implantation fluence underscores the critical interplay between electronic correlations and disorder, offering a new paradigm for the controlled engineering of interfacial quantum states in SrTiO3-based oxide heterostructures.

Topology has emerged as a fundamental property of many systems yet mostly limited to low dimensions. Here, we reveal the hidden topology in entangled states carrying orbital angular momentum (OAM), in arbitrary dimensions. For two-dimensional systems, we demonstrate multiple skyrmion topologies and their equivalence to ’t Hooft-Polyakov magnetic monopoles, experimentally connecting them to the Higgs field. In higher dimensions, we use non-Abelian gauge fields of SU(d) Yang-Mills theory to predict a rich tapestry of topological maps and their invariants, which we confirm experimentally for dimensionality up to seven, showing an underlying topology of 48 dimensions and a topological spectrum spanning over 17000 invariants. In addition to inducing robustness to perturbation, the topological spectrum enables probing them, by observing their emergent signatures in its non-topological spaces. The only degree of freedom we use to construct the topology is OAM, breaking away from the optical paradigm of polarisation-based spin-textured fields and forgoing the need for quantum state engineering. Our theoretical framework can be extrapolated to any dimension and degree of freedom, opening a distinct path for finding topologies in light.

We demonstrate a self-excitation protocol to generate truncated motional squeezed states in a quasi-two-dimensional Bose–Einstein condensate using intrinsic atom–atom interactions. By abruptly relaxing the transverse trapping potential, interaction energy transforms into kinetic energy, exciting a coherent superposition of motional states. The induced dynamic is beyond conventional collective mode approximation. Limited kinetic energy produces a truncated motional squeezed state with a non-Gaussian density distribution suitable for quantum state engineering. Using single-shot in situ absorption imaging, we develop a variance-based quantum tomography method to reconstruct the quantum state. Our experiment realized a self-excited squeezed state with a squeezing parameter χ=0.66±0.05, which is expected to give −5.73±0.4 dB squeezing for full-state. However, truncation reduces the squeezing to −5.03±0.2 dB due to limited Fock states. Interaction-driven self-excitation combined with single shot variance-based tomography provides a versatile mechanism for generating and characterizing non-Gaussian squeezed states in precision quantum metrology.

Non-Gaussian quantum states of bosons are a key resource in quantum information science with applications ranging from quantum metrology to fault-tolerant quantum computation. Generation of photonic non-Gaussian resource states, such as Schrödinger's cat and Gottesman-Kitaev-Preskill states, is challenging. In this work, we go beyond existing passive architectures and explore a broad set of adaptive schemes. Our numerical results demonstrate a consistent improvement in the probability of success and fidelity of generating these non-Gaussian quantum states with equivalent resources. We also explore the effect of loss as the primary limiting factor and observe that adaptive schemes lead to more desirable outcomes in terms of overall probability of success and loss tolerance. Our work offers a versatile framework for non-Gaussian resource state generation with the potential to guide future experimental implementations.

Preparation of nontrivial quantum states without introducing unwanted excitations or decoherence remains a central challenge in utilizing ultracold atomic systems for quantum simulation. We employ optimal control methods to realize fast, coherent splitting of a one-dimensional Bose-Einstein condensate, achieving negligible classical excitations while preserving quantum correlations. Furthermore, we explore two-step protocols in which controlled classical motion is first induced and subsequently suppressed via tailored control sequences. Our experiments highlight the potential of optimal control for quantum state engineering and dynamical control in many-body quantum systems.

Abstract Vector vortex beams, featuring spatially structured polarization states and helical phase fronts, emerge as a critical solution for enhancing optical information capacity beyond the constraints of traditional communication paradigms. In this paper, a coherent modulation strategy is established for creating two dimension (2D) vector vortex far‐field diffraction arrays through light‐atom interactions under electromagnetically induced transparency (EIT). A dynamically reconfigurable optical lattice is engineered via interference between a Gaussian‐coupled field and a vortex‐coupled field with adjustable topological charge. The atomic medium, when subjected to this lattice modulation, facilitates the diffraction of probe vector light fields into high‐order vector vortex diffracted spots. This system enables multi‐parameter tuning to significantly enhance diffraction efficiency. Results demonstrate that Comprehensive optimization of coupling field intensity, interference beam power distribution, and frequency detuning significantly enhances the relative diffraction efficiency. Moreover, the polarization state distribution of diffraction fields can be reconfigured by controlling optical lattice topological charges. This atomic medium‐based optical lattice modulation framework offers flexibility in tailoring structured light arrays, bridging fundamental studies of structured light‐matter interactions with advanced applications in high‐dimensional optical encoding, quantum state engineering, and multifunctional optical manipulation systems.

Two-photon interference, a quantum phenomenon arising from the principle of indistinguishability, is a powerful tool for quantum state engineering and plays a fundamental role in various quantum technologies. These technologies demand robust and efficient sources of quantum light, as well as scalable, integrable, and multifunctional platforms. In this regard, quantum optical metasurfaces (QOMs) are emerging as promising platforms for the generation and engineering of quantum light, in particular pairs of entangled photons (biphotons) via spontaneous parametric down-conversion (SPDC). Due to the relaxation of the phase-matching condition, SPDC in QOMs allows different channels of biphoton generation, such as those supported by overlapping resonances, to occur simultaneously. In previously reported QOMs, however, SPDC was too weak to observe such effects. Here, we develop QOMs based on [110]-oriented GaAs that provide an order-of-magnitude enhancement in SPDC rate, after accounting for the spectral bandwidth, compared to any other QOMs studied to date. This boosted efficiency allows the QOMs to support the simultaneous generation of SPDC from several spectrally overlapping optical modes. Using a linear polarizer, we intentionally erase the distinguishability between the biphotons from a high-Q quasi-bound-state-in-the-continuum resonance and a low-Q Mie resonance, which results in the first-time observation of two-photon interference, shown in the form of a Fano contour, in the spectrum of biphotons. This quantum interference can enrich the generation of entangled photons in metasurfaces. Their advanced multifunctionality, improved nonlinear response, ease of fabrication, and compact footprint of [110]-GaAs QOMs position them as promising platforms to fulfill the requirements of photonic quantum technologies.

The key concept of mobility edge, which marks the critical transition between extended and localized states in energy domain, has attracted significant interest in the cutting-edge frontiers of modern physics due to its profound implications for understanding localization and transport properties in disordered systems. However, a generic way to construct multiple mobility edges (MME) is still ambiguous and lacking. In this work, we propose a brief scheme to engineer both real and complex exact multiple mobility edges exploiting a few coupled one-dimensional quasiperiodic chains. We study the extended-localized transitions of coupled one-dimensional quasiperiodic chains along the chain direction. The model combines both the well-established quasiperiodicity and a kind of freshly introduced staggered non-reciprocity, which are aligned in two mutually perpendicular directions, within a unified framework. Based on analytical analysis, we predict that when the couplings between quasiperiodic chains are weak, the system will be in a mixed phase in which the localized states and extended states coexist and intertwine, thus lacking explicit energy separations. However, as the inter-chain couplings increase to certain strength, exact multiple mobility edges emerge. This prediction is clearly verified by concrete numerical calculations of the Fractal Dimension and the scaling index $β$. Moreover, we show that the combination of quasiperiodicity and the staggered non-reciprocity can be utilized to design and realize quantum states of various configurations. Our results reveal a brief and general scheme to implement exact multiple mobility edges for synthetic materials engineering.

Decoherence control of the dynamics of cat-like state by quantum state engineering: Thermal channel via non-Gaussian operation

Moiré potential formed in van der Waals heterostructures is predicted to feature multiple local minima functioning as orbital degree of freedom, which is an important ingredient for understanding intriguing strong correlation phenomena. However, an experimental demonstration of this moiré-orbital enabled quantum state engineering is still unexplored. Here, we report clear evidence of moiré-orbital resolved excitonic Mott insulating states in multiannealing H-type WSe_{2}/WS_{2} heterobilayers and demonstrate their application in generating spatially ordered excitonic quantum phases. This moiré orbital is evidenced by interlayer exciton emissions with an energy separation of ∼65 meV and further supported by our multiple field-dependent characterizations. Remarkably, the moiré orbital allows a sequential formation of correlated Mott insulating states, with the extracted onsite Hubbard interaction reaching ∼30 meV. A combined optical and electric doping allows control of strongly correlated quantum phases with various spatially ordered fermionic-bosonic orbital components.

Highly frequency-stable lasers are ubiquitous tools for optical-frequency metrology, precision interferometry, and quantum information science. While making a universally applicable laser is unrealistic, spectral noise can be tailored for specific applications. Here we report a high-power 698-nm clock laser with a maximum output of 4W and minimized frequency noise up to a few kHz Fourier frequency, together with long-term instability of 3.5×10−17 at one to thousands of seconds. The laser-frequency noise is precisely characterized with atom-based spectral analysis that employs a pulse sequence designed to suppress sensitivity to intensity noise. This method provides universally applicable tunability of the spectral response and analysis of quantum sensors over a wide frequency range. With the optimized laser system characterized by this technique, we achieve an average single-qubit Clifford gate fidelity of up to F12=0.99964(3) when simultaneously driving 3000 optical qubits with a homogeneous Rabi frequency ranging from 10 Hz to 1 kHz. This result represents the highest single optical-qubit-gate fidelity for a large number of atoms.

Quantum state engineering of light using intensity measurements and postselection