We examine the adiabatic preparation of spatially ordered Rydberg excitations of atoms in finite one-dimensional lattices by frequency-chirped laser pulses, as realized in a number of recent experiments simulating quantum Ising model. Our aims are to unravel the microscopic mechanism of the phase transition from the unexcited state of atoms to the antiferromagneticlike state of Rydberg excitations by traversing an extended gapless phase and to estimate the preparation fidelity of the target state in a moderately sized system amenable to detailed numerical analysis. We show that, despite its complexity, the interacting many-body system can be described as an effective two-level system involving a pair of lowest-energy instantaneous collective eigenstates of the time-dependent Hamiltonian. The final preparation fidelity of the target state can then be well approximated by the Landau-Zener formula, while the nonadiabatic population leakage during the passage can be estimated using a perturbative approach applied to the instantaneous collective eigenstates.
We examine the adiabatic preparation of spatially ordered Rydberg excitations of atoms in finite one-dimensional lattices by frequency-chirped laser pulses, as realized in a number of recent experiments simulating quantum Ising model. Our aims are to unravel the microscopic mechanism of the phase transition from the unexcited state of atoms to the antiferromagneticlike state of Rydberg excitations by traversing an extended gapless phase and to estimate the preparation fidelity of the target state in a moderately sized system amenable to detailed numerical analysis. We show that, despite its complexity, the interacting many-body system can be described as an effective two-level system involving a pair of lowest-energy instantaneous collective eigenstates of the time-dependent Hamiltonian. The final preparation fidelity of the target state can then be well approximated by the Landau-Zener formula, while the nonadiabatic population leakage during the passage can be estimated using a perturbative approach applied to the instantaneous collective eigenstates.
We examine the adiabatic preparation of spatially-ordered Rydberg excitations of atoms in finite one-dimensional lattices by frequency-chirped laser pulses, as realized in a number of recent experiments simulating quantum Ising model. Our aims are to unravel the microscopic mechanism of the phase transition from the unexcited state of atoms to the antiferromagnetic-like state of Rydberg excitations by traversing an extended gapless phase, and to estimate the preparation fidelity of the target state in a moderately sized system amenable to detailed numerical analysis. We find that, in the basis of the bare atomic states, the system climbs the ladder of Rydberg excitations predominantly along the strongest-amplitude paths towards the final ordered state. We show that, despite its complexity, the interacting many-body system can be described as an effective two-level system involving a pair of lowest-energy instantaneous collective eigenstates of the time-dependent Hamiltonian. The final preparation fidelity of the target state can then be well approximated by the Landau-Zener formula, while the nonadiabatic population leakage during the passage can be estimated using a perturbative approach applied to the instantaneous collective eigenstates.
Abstract We examine the adiabatic preparation of crystalline phases of Rydberg excitations in a one-dimensional lattice gas by frequency sweep of the excitation laser, as proposed by Pohl et al (2010 Phys. Rev. Lett. 104 043002 ) and recently realized experimentally by Schauß et al (2015 Science 347 1455 ). We find that the preparation of crystals of a few Rydberg excitations in a unitary system of several tens of atoms requires exceedingly long times for the adiabatic following of the ground state of the system Hamiltonian. Using quantum stochastic (Monte Carlo) wavefunction simulations, we show that realistic decay and dephasing processes affecting the atoms during the preparation lead to a final state of the system that has only a small overlap with the target crystalline state. Yet, the final number and highly sub-Poissonian statistics of Rydberg excitations and their spatial order are little affected by the relaxations.
We study the Landau-Zener (LZ) dynamics in a setup of two Rydberg atoms with time-dependent detuning, both linear and periodic, using both the exact numerical calculations as well as the method of adiabatic impulse approximation (AIA). By varying the Rydberg-Rydberg interaction strengths, the system can emulate different three-level LZ models, for instance, bow-tie and triangular LZ models. The LZ dynamics exhibits nontrivial dependence on the initial state, the quench rate, and the interaction strengths. For large interaction strengths, the dynamics is well captured by AIA. In the end, we analyze the periodically driven case, and AIA reveals a rich phase structure involved in the dynamics. The latter may find applications in quantum state preparation, quantum phase gates, and atom interferometry.
Dynamical Crossover in Landau−Zener Tunneling in Dissipative Rydberg Lattices
In this work, we investigate the excitation dynamics of a Rabi-coupled dissipative Rydberg lattice with a time-dependent detuning. The system is analyzed using (i) a Lindblad master equation within a mean-field approximation and (ii) an effective non-Hermitian Hamiltonian framework. While the mean-field approach captures the emergence of an antiferromagnetic order in the Rydberg excitation profile, the non-Hermitian description provides direct insight into the complex energy spectrum and its avoided crossings, which govern the Landau−Zener dynamics. We identify a regime in which the sublattice population imbalance vanishes near the avoided crossing, resulting in identical Landau−Zener probabilities on the two sublattices. Beyond a critical effective blockade strength there is a dynamical crossover to another regime in which the sublattice population imbalance persists through the avoided crossing, giving rise to sublattice-dependent Landau−Zener probabilities. Furthermore, Rydberg interactions prolong the lifetime of Landau−Zener-induced excitations in the presence of weak dissipation and strong Rabi coupling. In contrast, for weak Rabi coupling, the Rydberg blockade inhibits excitation and suppresses the Landau−Zener transition probability.
We present numerical calculations, and simulations performed on a Rydberg atom quantum simulator, of the adiabatic evolution of many-body quantum systems around a quantum phase transition. We demonstrate that the end-to-end transfer error, for a given process duration and dissipative losses, can be suppressed by adopting smooth initial and final scheduling functions for the Hamiltonian. We consider a one-dimensional mixed-field Ising model, as well as a chain of Rydberg atoms, and compare numerical calculations and experimental results for the end-to-end transfer error with different schedule functions. We show, in particular, that if the time dependent Hamiltonian is n times differentiable with vanishing 1st to nth order derivatives in the beginning and in the end, the infidelity with respect to the final adiabatic eigenstate scales as 1/Tn+1 when evolving for time T.
The W state, as a robust multipartite entangled state, plays an important role in quantum information processing, quantum network construction and quantum computing. In this paper, a three-level ladder-type Rydberg atomic system is placed into a Rydberg blocking sphere to form a superatom. Each superatom has many collective states including just one Rydberg excitation constrained by the Rydberg blockade effect. In the weak cavity field limit, at most one atom can be pumped into excited state, then we can describe the superatom by using a three-level ladder-type system. Afterwards we encode quantum information about the effective energy levels of Rydberg superatoms and propose a fast scheme for preparing the Rydberg superatom W state based on the superadiabatic iterative technique and quantum Zeno dynamics.This scheme can be achieved in only one step by controlling the laser pulses. In this scheme, the superatoms are trapped in spatially separated cavities connected by optical fibers, thereby greatly improving the feasibility of experimental manipulation. A remarkable feature is that it does not need to accurately control experimental parameters and interaction time. Meanwhile, the form of counterdiabatic Hamiltonian is the same as that of the effective Hamiltonian. Through numerical simulations, the fidelity of this scheme can reach 99.94%. Even considering decoherence effects, including atomic spontaneous emission and photon leakage, the fidelity can still exceed 97.5%, thereby further demonstrating the strong robustness of the solution. In addition, the Rabi frequency can be characterized as a linear superposition of Gaussian functions, and this representation significantly alleviates the complexity encountered in practical experiments. Futhermore, we also analyze the influence of parameter fluctuations on the fidelity, and the results show that this scheme is robust against parameter fluctuations. Finally, the present scheme is extended to the case of N Rydberg superatoms, which shows the scalability of our scheme.