Hybrid systems of laser-cooled trapped ions and ultracold atoms combined in a single experimental setup have recently emerged as new platform for fundamental research quantum physics. This paper reviews the theoretical progress on cold hybrid ion-atom which aim to combine best features two well-established fields. We provide broad overview description mixtures their applications, report advances experiments with Paul or dipole traps overlapped cloud atoms, directly produced Bose-Einstein...

Abstract Quantum technologies will ultimately require manipulating many-body quantum systems with high precision. Cold atom experiments represent a stepping stone in that direction: degree of control has been achieved on increasing complexity. However, this is still sub-optimal. In many scenarios, achieving fast transformation crucial to fight against decoherence and imperfection effects. Optimal theory believed be the ideal candidate bridge gap between early stage proof-of-principle...

We investigate the optimal control of open quantum systems, in particular, mutual influence driving and dissipation. A stochastic approach to open-system is developed, using a generalized version Krotov's iterative algorithm, with no need for Markovian or rotating-wave approximations. The application harmonic degree freedom reveals cooperative effects dissipation that standard treatment cannot capture. Remarkably, can modify dynamics point where entropy change turns negative, thus achieving...

We propose and theoretically investigate a hybrid system composed of crystal trapped ions coupled to cloud ultracold fermions. The form periodic lattice induce band structure in the atoms. This combines advantages scalability tunability atomic systems with high fidelity operations detection offered by ion systems. It also features close analogies natural solid-state systems, as degrees freedom couple phonons lattice, thereby emulating system. Starting from microscopic many-body Hamiltonian,...

Abstract The presence of strong interactions in a many-body quantum system can lead to variety exotic effects. Here we show that even comparatively simple setup consisting charged impurity weakly interacting bosonic medium the competition length scales gives rise highly correlated mesoscopic state. Using Monte Carlo simulations, unravel its vastly different polaronic properties compared neutral impurities. Moreover, identify transition between regime amenable conventional perturbative...

Abstract Induced interactions and bound states of charge carriers immersed in a quantum medium are crucial for the investigation transport. Ultracold atom-ion systems can provide convenient platform studying this problem. Here, we investigate static properties one two ionic impurities bosonic bath using Monte Carlo methods. We identify three bipolaronic regimes depending on strength potential number its two-body states: perturbative regime resembling situation pair neutral impurities,...

We propose a two-qubit collisional phase gate that can be implemented with available atom chip technology and present detailed theoretical analysis of its performance. The is based on earlier schemes, but uses qubit state pair an experimentally demonstrated, very long coherence lifetime. Microwave near fields play key role in our implementation as means to realize the state-dependent potentials required for conditional dynamics. Quantum control algorithms are used optimize employ circuit...

Abstract The Ramsey interferometer is a prime example of precise control at the quantum level. It usually implemented using internal states atoms, molecules or ions, for which powerful manipulation procedures are now available. Whether it possible to external degrees freedom more complex, interacting many-body systems this level remained an open question. Here we demonstrate two-pulse Ramsey-type non-classical motional Bose–Einstein condensate in anharmonic trap. sequences used manipulate...

We propose to use a single mesoscopic ensemble of trapped polar molecules for quantum computing. A ``holographic register'' with hundreds qubits is encoded in collective excitations definite spatial phase variations. Each pattern uniquely addressed by optical Raman processes classical fields, while one- and two-qubit gates qubit readout are accomplished transferring the states stripline microwave cavity field Cooper pair box where controllable two-level unitary dynamics detection governed fields.

We present an in-depth many-body investigation of the so-called mesoscopic molecular ions that can buildup when ion is immersed into atomic Bose-Einstein condensate in one dimension. To this end, we employ multilayer multiconfiguration time-dependent Hartree method for mixtures ultracold bosonic species solving underlying Schr\"odinger equation. This enables us to unravel actual structure such massive charged molecules from a microscopic perspective. Laying out their phase diagram with...

We theoretically investigate trapped ions interacting with atoms that are coupled to Rydberg states. The strong polarizabilities of the levels increases interaction strength between and by many orders magnitude, as compared case ground state atoms, may be mediated over micrometers. calculate such interactions can used generate entanglement an atom motion or internal ion. Furthermore, ion could a bus for mediating spin-spin atomic spins in analogy much employed techniques trap quantum...

We analyze the equilibrium properties of a weakly interacting, trapped quasi-one-dimensional Bose gas at finite temperatures and compare different theoretical approaches. focus in particular on two stochastic theories: number-conserving Bogoliubov (NCB) approach Gross-Pitaevskii equation (SGPE) that have been extensively used numerical simulations. Equilibrium like density profiles, correlation functions, condensate statistics are compared to predictions based upon number alternative...

We theoretically investigate the properties of a double-well bosonic Josephson junction coupled to single trapped ion. find that coupling between wells can be controlled by internal state ion, which used for studying mesoscopic entanglement two systems and measure their interaction with high precision. As particular example we consider $^{87}\mathrm{Rb}$ atom small Bose-Einstein condensate $^{171}\mathrm{Yb}^{+}$ calculate interwell rates reaching hundreds Hz, while dependence amounts tens...

We extend the concept of quantum speed limit -- minimal time needed to perform a driven evolution complex interacting many-body systems. investigate prototypical system, bosonic Josephson junction, at increasing levels complexity: (a) within two-mode approximation {corresponding to} nonlinear two-level (b) mean-field level by solving Gross-Pitaevskii equation in double well potential, and (c) an exact time-dependent Schr\"odinger equation. propose control protocol transfer atoms from ground...

We consider a trapped atomic ensemble of interacting bosons in the presence single ion quasi one dimensional geometry. Our study is carried out by means newly developed multilayer-multiconfiguration time-dependent Hartree method for bosons, numerical exact approach to simulate quantum many-body dynamics. In particular, we are interested scenario which so strongly that its motion can be effectively neglected. This enables us focus on only. With development model potential atom-ion...

We analyze theoretically the dynamics of an atomic double-well system with a single ion trapped in its center. find that tunneling rate between wells depends both on spin via short-range spin-dependent atom-ion scattering length and motional state rates reaching hundreds hertz. A protocol is presented could transport atom from one well to other, depending (Fock) within few milliseconds. This phonon-atom coupling interest for creating entangled states may form building block constructing...

We demonstrate a source for correlated pairs of atoms characterized by two opposite momenta and spatial modes forming Bell state only involving external degrees freedom. characterize the emitted atom beams observing strong number squeezing up to −10 dB in two-particle emission. furthermore genuine interference normalized second-order correlation function g(2) relative atoms.Received 3 October 2020Revised 9 December 2020Accepted 13 January 2021Corrected 10 May...

We study the dynamics of Bose–Einstein condensates in time-dependent microtraps for purpose understanding influence mean field interaction on performance interferometers. identify conditions where nonlinearity due to atom interactions increases sensitivity interferometers a phase shift. This feature is connected with adiabatic generation dark soliton. analyse robustness this phenomenon respect thermal fluctuations, excited near fields an electromagnetic surface trap.

We explore the quantum dynamics of a one-dimensional trapped ultracold ensemble bosonic atoms triggered by sudden creation single ion. The numerical simulations are performed means ab initio multiconfiguration time-dependent Hartree method for bosons which takes into account all correlations. is analyzed via cluster expansion approach, adapted to systems fixed particle number, provides comprehensive understanding occurring many-body processes. After transient during atomic separates...

We investigate the sensitivity of an ion sensor in determining temperature atomic Fermi gas. Our study extends to charged impurities proposal by M. T. Mitchison et al. Phys. Rev. Lett. 125, 080402 (2020), where neutral were used as situ thermometer quantum find that long-range character atom-ion interaction enhances thermometer's for certain system parameters. In addition, we impact motional state on assuming it is confined a harmonic trap. observe noticeably influenced its spatial...

We present a detailed, realistic analysis of the implementation proposal for quantum phase gate based on atomic vibrational states, specializing it to neutral rubidium atoms atom chips. show how create double--well potential with static currents chips, using all relevant parameters values that are achieved technology. The barrier between two wells can be modified by varying in order realize qubit states encoded external degree freedom. performance is analyzed through numerical simulations;...

We develop a quantum simulator architecture that is suitable for the simulation of $\text{U}(1)$ Abelian gauge theories such as electrodynamics. Our approach relies on ability to control hopping particle through barrier by means internal states neutral or charged impurity sitting at barrier. This scheme experimentally feasible, correlated does not require fine-tuning intra- and interspecies interactions. investigate applicability in double-well potential, which basic building block...

The dynamics of a bosonic Josephson junction in the presence trapped ion is studied with different computational techniques, where control many-body physics self-trapped regime and tunneling validated described.

We investigate confinement-induced resonances in a system composed of tightly trapped ion and moving atom waveguide. determine the conditions for appearance such broad region---from ``long-wavelength'' limit to opposite case when typical length scale atom-ion polarization potential essentially exceeds transverse waveguide width. find considerable dependence resonance position on atomic mass which, however, disappears ``long-wavelength zero-energy'' limit, where known result confined...