Jaynes-Cummings-Hubbard Model Research Articles

Quench dynamics in the Jaynes-Cummings-Hubbard and Dicke models

Both the Jaynes-Cummings-Hubbard (JCH) and Dicke models can be thought of as idealised models of a quantum battery. In this paper we numerically investigate the charging properties of both of these models. The two models differ in how the two-level systems are contained in cavities. In the Dicke model, the N two-level systems are contained in a single cavity, while in the JCH model the two-level systems each have their own cavity and are able to pass photons between them. In each of these models we consider a scenario where the two-level systems start in the ground state and the coupling parameter between the photon and the two-level systems is quenched. Each of these models display a maximum charging power that scales with the size of the battery N and no super charging was found. Charging power also scales with the square root of the average number of photons per two-level system m for both models. Finally, in the JCH model, the power was found to charge inversely with the photon-cavity coupling κ.

Site-dependent control of polaritons in the Jaynes–Cummings–Hubbard model with trapped ions

We demonstrate the site-dependent control of polaritons in the Jaynes–Cummings–Hubbard (JCH) model with trapped ions. When a linear ion crystal is illuminated with optical beams which are nearly resonant to the red-sideband (RSB) transition for the radial vibrational direction, quasiparticles called polaritonic excitations or polaritons can exist as conserved particles. Here, each polariton is a superposition of one internal excitation and one vibrational quantum (phonon). Polaritons can freely hop between ion sites in a homogeneous configuration, while their motion can be externally controlled by modifying the parameters for the optical beams site-dependently. We demonstrate the blockade of polariton hopping in a system of two ions by the individual control of the frequency of the optical beams illuminating each ion. A JCH system consisting of polaritons in a large number of ion sites can be considered an artificial many-body system of interacting particles and the technique introduced here can be used to exert fine local control over such a system, enabling detailed studies of both its quasi-static and dynamic properties.

Particle-Hole Ansatz in the Jaynes-Cummings-Hubbard Model

A recurrence relation ansatz between annihilation operators applied to the hopping interaction term of the Jaynes-Cummings-Hubbard model (JCHM) reduces the JCHM to that of the ordinary Jaynes-Cummings model (JCM), albeit, with a boson energy depending on the hopping strength. This allows us to calculate the phase diagram for the Mott-to-superfluid phase transition and the critical hopping strength as a function of the detuning.

Normal and abnormal thermalization indicators in a one-dimensional low-density Jaynes-Cummings Hubbard model with and without dipole-dipole interaction.

In the one-dimensional low-density Jaynes-Cummings Hubbard (JCH) model, we find that when the hopping strength is much smaller than the coupling strength, the average restricted energy gap ratio exhibits an abnormal statistical behavior that is neither a Poisson nor a Gaussian orthogonal ensemble. But the average half-chain entanglement entropy exhibits ergodicity, and the eigenstate thermalization hypothesis (ETH) is valid for the observable. These results are quite different from those of the standard JCH model. In addition, when the hopping and the coupling strengths are of the same order, quantum chaos still appears in the low-density JCH model, which is in contrast to the integrability of the one-dimensional hard-core bosons. Finally, the dipole-dipole interaction breaks the particle-hole symmetry and leads the abnormal statistical properties to be closer to those of the integrable system at the weak hopping strength limit, but the quantum chaos properties cannot be affected when the hopping strength is of the same order as the coupling strength. Our results demonstrate the counterintuitive behavior in the low-density JCH model and explain the physics behind them from the perspective of the energy spectrum.

Observation of Non-Markovian Spin Dynamics in a Jaynes-Cummings-Hubbard Model Using a Trapped-Ion Quantum Simulator.

The Jaynes-Cummings-Hubbard (JCH) model is a fundamental many-body model for light-matter interaction. As a leading platform for quantum simulation, the trapped ion system has realized the JCH model for two to three ions. Here, we report the quantum simulation of the JCH model using up to 32 ions. We verify the simulation results even for large ion numbers by engineering low excitations and thus low effective dimensions; then we extend to 32 excitations for an effective dimension of 2^{77}, which is difficult for classical computers. By regarding the phonon modes as baths, we explore Markovian or non-Markovian spin dynamics in different parameter regimes of the JCH model, similar to quantum emitters in a structured photonic environment. We further examine the dependence of the non-Markovian dynamics on the effective Hilbert space dimension. Our Letter demonstrates the trapped ion system as a powerful quantum simulator for many-body physics and open quantum systems.

Steady-state quantum phase transition in a Jaynes–Cummings–Hubbard model with quantized center-of-mass motions

Steady-state quantum phase transition in a Jaynes–Cummings–Hubbard model with quantized center-of-mass motions

Polariton blockade in the Jaynes–Cummings–Hubbard model with trapped ions

We have experimentally observed the dynamics of a single polariton and two polaritons in a two-ion chain. By driving two trapped ions at a motional blue-sideband (BSB) transition, we realize the anti-Jaynes–Cummings–Hubbard (JCH) model. When a single polariton exists in a trapped-ion chain, the polariton hops between the ion sites. On the other hand, when there are single polaritons at each ion site, the hopping of the polaritons is suppressed because of the polariton–polariton interaction induced by the nonlinearity of the anti-Jaynes–Cummings (JC) interaction, thereby realizing the blockade of polariton hopping in the anti-JCH model with trapped ions. Our work is a step towards the development of a trapped-ion based quantum simulator for strongly interacting polaritonic systems.

Two-photon Rabi-Hubbard and Jaynes-Cummings-Hubbard models: Photon-pair superradiance, Mott insulator, and normal phases

We study the ground state phase diagrams of two-photon Dicke, the one-dimensional Jaynes-Cummings-Hubbard (JCH), and Rabi-Hubbard (RH) models using mean field, perturbation, quantum Monte Carlo (QMC), and density matrix renormalization group (DMRG) methods. We first compare mean field predictions for the phase diagram of the Dicke model with exact QMC results and find excellent agreement. The phase diagram of the JCH model is then shown to exhibit a single Mott insulator lobe with two excitons per site, a superfluid (SF, superradiant) phase and a large region of instability where the Hamiltonian becomes unbounded. Unlike the one-photon model, there are no higher Mott lobes. Also unlike the one-photon case, the SF phases above and below the Mott are surprisingly different: Below the Mott, the SF is that of photon {\it pairs} as opposed to above the Mott where it is SF of simple photons. The mean field phase diagram of the RH model predicts a transition from a normal to a superradiant phase but none is found with QMC.

Pfaffian states in coupled atom-cavity systems

Coupled atom-cavity arrays, such as those described by the Jaynes-Cummings Hubbard model, have the potential to emulate a wide range of condensed matter phenomena. In particular, the strongly correlated states of the fractional quantum Hall effect can be realised. At some filling fractions, the fraction quantum Hall effect has been shown to possess ground states with non-abelian excitations. The most well studied of these states is the Pfaffian state of Moore and Read, which is the groundstate of a Hall Liquid with a 3-body interaction. In this paper we show how an effective 3-body interaction can be generated within the Cavity QED framework, and that a Pfaffian-like groundstate of these systems exists.

Fermionized photons in the ground state of one-dimensional coupled cavities

The density matrix renormalization group algorithm is used to characterize the ground states of one-dimensional coupled cavities in the regime of low photon densities. Numerical results for photon and spin excitation densities, one- and two-body correlation functions, superfluid and condensate fractions, as well as the entanglement entropy and localizable entanglement are obtained for the Jaynes-Cummings-Hubbard (JCH) model and are compared with those for the Bose-Hubbard (BH) model where applicable. The results indicate that a Tonks-Girardeau phase, in which the photons are strongly fermionized, appears between the Mott-insulating and superfluid phases as a function of the intercavity coupling. In fact, the superfluid density is found to be zero in a wide region outside the Mott-insulator phase boundary. The presence of two different species of excitation (spin and photon) in the JCH model gives rise to properties with no analog in the BH model, such as the (quasi)condensation of spin excitations and the spontaneous generation of entanglement between the atoms confined to each cavity.

Disorder-correlation-frequency-controlled diffusion in the Jaynes-Cummings–Hubbard model

We investigate time-dependent stochastic disorder in the one-dimensional Jaynes-Cummings-Hubbard model and show that it gives rise to diffusive behaviour. We find that disorder correlation frequency is effective in controlling the level of diffusivity. In the defectless system the mean squared displacement (MSD), which is a measure of the diffusivity, increases with increasing disorder frequency. Contrastingly, when static defects are present the MSD increases with disorder frequency only at lower frequencies; at higher frequencies, increasing disorder frequency actually reduces the MSD.

Topological photonic bands in two-dimensional networks of metamaterial elements

We show that topological frequency band structures emerge in two-dimensional electromagnetic lattices of metamaterial components without the application of an external magnetic field. The topological nature of the band structure manifests itself by the occurrence of exceptional points in the band structure or by the emergence of one-way guided modes. Based on an electromagnetic network with nearly flat frequency bands of nontrivial topology, we propose a coupled-cavity lattice made of superconducting transmission lines and cavity QED components, which is described by the Jaynes–Cummings–Hubbard model and can serve as a simulator of the fractional quantum Hall effect.

Excitations of Strongly Correlated Lattice Polaritons

We present an analytic slave-boson approach to calculate the elementary excitations of the Jaynes-Cummings-Hubbard model (JCHM) describing strongly correlated polaritons on a lattice in various quantum optical systems. In the superfluid phase near the Mott transition we find a gapless, linear Goldstone mode and a gapped amplitude mode corresponding to phase and density fluctuations, respectively. The sound velocity of the Goldstone mode develops a peculiar anomaly as a function of detuning at low densities, which persists into the weakly interacting regime of a polariton BEC.

Analytic approximations to the phase diagram of the Jaynes-Cummings-Hubbard model

We discuss analytic approximations to the ground-state phase diagram of the homogeneous Jaynes-Cummings-Hubbard (JCH) Hamiltonian with general short-range hopping. The JCH model describes, e.g., radial phonon excitations of a linear chain of ions coupled to an external laser field tuned to the red motional sideband with Coulomb-mediated hopping or an array of high-$Q$ coupled cavities containing a two-level atom and photons. Specifically, we consider the cases of a linear array of coupled cavities and a linear ion chain. We derive approximate analytic expressions for the boundaries between Mott-insulating and superfluid phases and give explicit expressions for the critical value of the hopping amplitude within the different approximation schemes. In the case of an array of cavities, which is represented by the standard JCH model, we compare both approximations to numerical data from density-matrix renormalization-group calculations.