Here we present the quantum storage of three-dimensional orbital-angular-momentum photonic entanglement in a rare-earth-ion-doped crystal. The properties and process are confirmed by violation Bell-type inequality generalized to three dimensions after (S=2.152±0.033). fidelity memory is 0.993±0.002, as determined through complete tomography dimensions. An assessment visibility stored weak coherent pulses higher-dimensional spaces demonstrates that highly reliable for 51 spatial modes. These...

Variational quantum algorithms (VQAs) are widely applied in the noisy intermediate-scale era and expected to demonstrate advantage. However, training VQAs faces difficulties, one of which is so-called barren plateaus (BP) phenomenon, where gradients cost functions vanish exponentially with number qubits. In this paper, inspired by transfer learning, knowledge pre-solved tasks could be further used a different but related work efficiency improved, we report parameter initialization method...

Abstract Quantum processes of inherent dynamical nature, such as quantum walks, defy a description in terms an equilibrium statistical physics ensemble. Until now, identifying the general principles behind underlying unitary dynamics has remained key challenge. Here, we show and experimentally observe that split-step walks admit characterization topological order parameter (DTOP). This integer-quantized DTOP measures, at given time, winding geometric phase accumulated by wavefunction during...

The spin-1/2 $J_1$-$J_2$ Heisenberg model on square lattices are investigated via the finite projected entangled pair states (PEPS) method. Using recently developed gradient optimization method combining with Monte Carlo sampling techniques, we able to obtain ground energies that competitive best results. calculations show there is no N\'eel order, dimer order and plaquette in region of 0.42 $\lesssim J_2/J_1\lesssim$ 0.6, suggesting a single spin liquid phase intermediate region....

$\mathcal{P}\mathcal{T}$-symmetric theory is developed to extend quantum mechanics a complex region, but it wins its great success first in classical systems, for example, optical waveguides and electric circuits, etc., because there are so many counterintuitive phenomena striking applications, including unidirectional light transport, $\mathcal{P}\mathcal{T}$-enhanced sensors (one kind of exceptional-point-based sensor), wireless power transfer. However, these applications mostly based on...

Exceptional points (EPs), at which more than one eigenvalue and eigenvector coalesce, are unique spectral features of non-Hermiticity (NH) systems. They exist widely in open systems with complex energy spectra. We experimentally demonstrate the appearance paired EPs a periodical-driven degenerate optical cavity along synthetic orbital angular momentum dimension tunable parameter. The complex-energy band structures key EPs, i.e., their bulk Fermi arcs, parity-time symmetry breaking...

We propose a scheme to demonstrate fractional statistics of anyons in an exactly solvable lattice model proposed by Kitaev that involves four-body interactions. The required many-body ground state, as well the anyon excitations and their braiding operations, can be conveniently realized through dynamic laser manipulation cold atoms optical lattice. Because perfect localization this model, we show quantum circuit with only six qubits is enough for demonstration basic anyons. This opens up...

The physical impact and the testability of Kochen-Specker (KS) theorem is debated because fact that perfect compatibility in a single quantum system cannot be achieved practical experiments with finite precision. Here, we follow proposal A. Cabello M. T. Cunha [Phys. Rev. Lett. 106, 190401 (2011)], present compatibility-loophole-free experimental violation an inequality noncontextual theories by two spatially separated entangled qutrits. A maximally qutrit-qutrit state fidelity as high...

Entanglement and the wave function description are two of core concepts that make quantum mechanics such a unique theory. A method to directly measure function, using weak values, was demonstrated by Lundeen et al. [Nature 474, 188 (2011)]. However, it is not applicable scenario disjoint systems, where nonlocal entanglement can be crucial element, since requires obtaining values observables. Here, for first time, we propose bipartite system, modular values. The experimentally implemented...

Projected entangled pair states (PEPS) methods have been proven to be powerful tools solve strongly correlated quantum many-body problems in two dimensions. However, due the high computational scaling with virtual bond dimension $D$, a practical application, PEPS are often limited rather small dimensions, which may not large enough for some highly systems, instance, frustrated systems. Optimization of ground state using imaginary time evolution method simple update scheme go larger...

We report the experimental measurement of winding number in an unitary chiral quantum walk. Fundamentally, spin-orbit coupling discrete time walks is implemented via birefringent crystal collinearly cut based on time-multiplexing scheme. Our protocol compact and avoids extra loss, making it suitable for realizing genuine single-photon at a large-scale. By adopting heralded as walker with high resolution technology detection, we carry out 50-step Hadamard discrete-time walk fidelity up to...

How to properly certify the quantum function of a process (device) is one key problems in information science, particularly, for beyond its classical counterpart. To verify teleportation critical task because fundamental roles communication and computation. Here, we experimentally certified nonclassical with setting by random robustness introduced [Phys. Rev. Lett. 119, 110501 (2017)]. Our results show that convenient powerful verifying entanglement.

The initialization of a quantum system into certain state is crucial aspect information science. While variety measurement strategies have been developed to characterize how well the initialized, for given one, there in general trade-off between its efficiency and accessible state. Conventional tomography can unknown states while requiring exponentially expensive time-consuming postprocessing. Alternatively, recent theoretical breakthroughs show that verification provides technique quantify...

Quantum memories for light are essential building blocks quantum repeaters and networks. Integrated operations of could enable scalable application with low-power consumption. However, the photonic storage lifetime in integrated devices has so far been limited to tens microseconds, falling short requirements practical applications. Here, we demonstrate qubits 1.021 milliseconds based on a laser-written optical waveguide fabricated 151 Eu 3+ :Y 2 SiO 5 crystal. Spin dephasing is mitigated...

We experimentally show that nonlocality can be produced from single-particle contextuality by using two-particle correlations which do not violate any Bell inequality themselves. This demonstrates come an a priori different simpler phenomenon, and connects nonlocality, the two critical resources for, respectively, quantum computation secure communication. From perspective of information, our experiment constitutes proof principle systems used simultaneously for both

Entanglement generation in discrete time quantum walks is deemed to be another key property beyond the transport behaviors.The latter has been widely used investigating localization or topology walks.However, there are few experiments involving former for challenges full reconstruction of final wave function.Here, we report an experiment demonstrating enhancement entanglement using dynamic disorder.Through reconstructing local spinor state each site, von Neumann entropy can obtained and...

Abstract The Kibble-Zurek mechanism is the paradigm to account for nonadiabatic dynamics of a system across continuous phase transition. Its study in quantum regime hindered by requisite ground state cooling. We report experimental simulation critical transverse-field Ising model set Landau-Zener crossings pseudo-momentum space, that can be probed with high accuracy using single trapped ion. test momentum space and find measured scaling excitations accordance theoretical prediction.

It is hard to stabilize the p-wave superfluid state of cold atomic gas in free space due inelastic collisional losses. We consider Feshbach resonance an optical lattice, and show that it possible have a stable where multi-atom loss suppressed through quantum Zeno effect. derive effective Hamiltonian for this system, calculate its phase diagram one-dimensional lattice. The results rich transitions between different types insulator states induced either by interaction or dissipation.

Synthetic dimensions based on particles' internal degrees of freedom, such as frequency, spatial modes and arrival time, have attracted significant attention. They offer ideal large-scale lattices to simulate nontrivial topological phenomena. Exploring more synthetic is one the paths toward higher dimensional physics. In this work, we design experimentally control coupling among consisting intrinsic photonic orbital angular momentum spin freedom in a degenerate optical resonant cavity, which...

Noise-enhanced applications in open quantum walk (QW) have recently seen a surge due to their ability improve performance. However, verifying the success of QW is challenging, as mixed-state tomography resource-intensive process, and implementing all required measurements almost impossible various physical constraints. To address this challenge, we present neural-network-based method for reconstructing mixed states with high fidelity (~97.5%) while costing only 50% number typically...

Standard weak measurement (SWM) has been proved to be a useful ingredient for measuring small longitudinal phase change (LPC) [X. Y. Xu, Kedem, K. Sun, L. Vaidman, C. F. Li, and Guang-Can Guo, Phys. Rev. Lett. 111, 033604 (2013)]. In these SWM proposals, the working regime is selected where relative between orthogonal components zero, LPC can detected by shift of meter state, i.e., time frequency domain, which are conjugated observables. Here, we show that an extra bias significantly improve...

Spin-1/2 two-legged ladders respecting inter-leg exchange symmetry and D2 spin rotation have new protected topological (SPT) phases which are different from the Haldane phase. Three of SPT tx,ty,tz, all two-fold degenerate edge states on each end open boundaries. However, in response to magnetic field. For example, tz phase will be split by field along z-direction, but not fields x- y-directions. We give Hamiltonian that realizes demonstrate a proof-of-principle quantum simulation scheme for...

Identifying the general mechanics behind equilibration of a complex isolated quantum system towards state described by only few parameters has been focus attention in non-equilibrium thermodynamics. And several experimentally unproven conjectures are proposed for statistical description (non-)integrable models. The plausible eigenstate thermalization hypothesis (ETH), which suggests that each energy itself is thermal, plays crucial role understanding non-integrable systems; it commonly...

Abstract Quantum entanglement is the key resource for quantum information processing. Device-independent certification of entangled states a long standing open question, which arouses concept self-testing. The central aim self-testing to certify state and measurements systems without any knowledge their inner workings, even when used devices cannot be trusted. Specifically, utilizing Bell’s theorem, one can infer appearance certain maximum violation observed, e.g., self-test singlet using...