Spin-dependent optical superlattice

Abstract

We propose and implement a lattice scheme for coherently manipulating atomic spins. Using the vector light shift and a superlattice structure, we demonstrate experimentally the capability on parallel spin addressing in double-wells and square plaquettes with subwavelength resolution. Quantum coherence of spin manipulations is verified through measuring atom tunneling and spin exchange dynamics. Our experiment presents a building block for engineering many-body quantum states in optical lattices for realizing quantum simulation and computation tasks.Ultracold atoms in optical lattices constitute a promising system for creating multipartite entangled states [1,2], which is an essential resource for quantum information processing [3,4]. As the neutral atoms prepared in the Mott insulating state consist of highly ordered quantum registers [5,6], multipartite entanglement can be generated via parallelly addressing single atoms together with two-body interactions [3,[7][8][9]. Following this route, sub-lattice addressing and √ SWAP operations in double-wells (DWs) were demonstrated [10,11], where the atomic spins in decoupled DW arrays were addressed by ultilizing the spin-dependent effect [10,12]. However, extending these entangled pairs to a one-dimensional (1D) chain or a two-dimensional (2D) cluster remains challenging due to the lack of control over inter-well couplings [13]. In this context, a bichromatic lattice referred as "superlattice" provides an alternative degree of freedom to connect the entangled pairs by tuning the relative lattice phase [14,15]. Besides the √ SWAP operation in such superlattices, site-selective single-qubit addressing is further required to create multipartite cluster states for measurement-based quantum computation [4,8].In this Letter, we demonstrate a spin-dependent optical superlattice for coherently addressing and manipulating atomic spins. Such a lattice configuration allows one to first address even/odd rows of spins in parallel and then create entangled pairs, as well as to enable further connection of the pairs to form a multipartite entangled state with high fidelity. This configuration offers an efficient way for spin addressing in higher dimensions [16] and meanwhile becomes a powerful tool in detecting the quantum correlations of entangled states [17].The optical lattice consists of two far-detuned lasers, one generates a local effective magnetic gradient, and the other one isolates the system into DWs and forms imbalanced structures for different spin states. To illustrate the spin-dependent optical potential, we consider an alkali atom placed inside a far-detuned laser field [12,18,19]. The monochromatic light field has a complex notation E(x, t) = E(x) exp(−iωt) + c.c, where E represents the positive-frequency part with the driving frequency ω. The optical potential for the atom in the

Observation of unconventional many-body scarring in a quantum simulator

“…We initialize the experiment by employing a superlattice in the y-direction to prepare a n=2 Mott insulator in the left (odd) sites of the double wells with 99.2% fidelity, while removing all atoms on the right (even) sites via site-dependent addressing [39,40]. This gives us the initial state |ψ 0 = |Z 2 = |2020 .…”

Interaction-induced topological bound states and Thouless pumping in a one-dimensional optical lattice

“…With the theory of describing the many-body topological properties in hand, we would like to explore the existence of interaction-induced topological states. We consider two spin-1/2 particles trapped by a state-dependent optical lattices [25][26][27][28]. The state-dependent lattices considered here consists of two lattices, which have the same periodicity but different phase ∆φ.…”

Observation of information flow in the anti-𝒫𝒯-symmetric system with nuclear spins

“…However, there are limited investigations on another important counterpart anti-PT -symmetry, which means the system Hamiltonian is anti-commutative with the joint PT operator {H, PT } = 0. Some relevant experimental demonstrations have been realized in atoms [29][30][31], optical [32][33][34][35][36][37], electrical circuit resonators [38] and diffusive systems [39]. Quantum processes such as symmetry breaking transition, observation of exceptional point and simulation of anti-PT -symmetric Lorentz dynamics have been presented in these experiments [29,33,37,38], whereas the novel characteristics of entanglement [17][18][19] and information flow [22][23][24] in the anti-PT -symmetric system, which would present various phenomena different from Hermitian quantum mechanics and reveal the relationship between system and environment, have not been fully thorough investigated in the experiment.In this work, we propose an algorithm for the simulation of universal anti-PT -symmetric evolution with quantum circuit model and report the first experimental observation of information flow oscillation in anti-PT -symmetric system on Nuclear Magnetic Resonance quantum computing platform.…”