A method is proposed to cool down atoms in a harmonic trap without phase-space compression as perfectly slow adiabatic expansion, i.e., keeping the populations of instantaneous initial and final levels invariant, but much shorter time. This may require that becomes an expulsive parabolic potential some time interval. The cooling times achieved are also than previous minimal using optimal-control bang-bang methods real frequencies.

We report on the engineering of a nondispersive (flat) energy band in geometrically frustrated lattice micropillar optical cavities. By taking advantage non-Hermitian nature our system, we achieve bosonic condensation exciton polaritons into flat band. Because infinite effective mass such band, condensate is highly sensitive to disorder and fragments localized modes reflecting elementary eigenstates produced by geometric frustration. This realization offers novel approach studying coherent...

Mediated photon-photon interactions are realized in a superconducting coplanar waveguide cavity coupled to charge qubit. These non-resonant blockade the transmission of photons through cavity. This so-called dispersive photon is characterized by measuring total transmitted power while varying energy spectrum incident on A staircase with four distinct steps observed and can be understood an analogy electron transport Coulomb quantum dots. work differs from previous efforts that cavity-qubit...

Abstract The Jaynes‐Cummings model describes the coupling between photons and a single two‐level atom in simplified representation of light‐matter interactions. In circuit QED, this is implemented by combining microwave resonators superconducting qubits on microchip with unprecedented experimental control. Arranging form lattice realizes new kind Hubbard model, Jaynes‐Cummings‐Hubbard which elementary excitations are polariton quasi‐particles. Due to genuine openness photonic systems, QED...

We demonstrate a coupled cavity realization of Bose Hubbard dimer to achieve quantum limited amplification and generate frequency entangled microwave fields with squeezing parameters well below -12 dB. In contrast previous implementations parametric amplifiers our can be operated both as degenerate nondegenerate amplifier. The large measured gain-bandwidth product more than 250 MHz for operation the saturation at input photon numbers high 2000 per us are expected improvable even further,...

We study the coherence and fluorescence properties of coherently pumped dissipative Jaynes-Cummings-Hubbard model describing polaritons in a coupled-cavity array. At weak hopping we find strong signatures photon blockade similar to single-cavity systems. state photons array depends on its size. While persists dimer consisting two coupled cavities, coherent forms an extended lattice, which can be described terms semi-classical model.

Here, we report the experimental observation of a dynamical quantum phase transition in strongly interacting open photonic system. The system studied, comprising Jaynes-Cummings dimer realized on superconducting circuit platform, exhibits dissipation-driven localization transition. Signatures homodyne signal and photon number reveal this to be from regime classical oscillations into macroscopically self-trapped state manifesting revivals, fundamentally phenomenon. This experiment also...

We present an analytic strong-coupling approach to the phase diagram and elementary excitations of Jaynes-Cummings-Hubbard model describing a superfluid-insulator transition polaritons in array coupled QED cavities. In Mott phase, we find four modes corresponding particle or hole with lower upper polaritons, respectively. Simple formulas are derived for dispersion spectral weights within random-phase approximation (RPA). The boundary is calculated beyond RPA by including leading correction...

We show that photons in two tunnel-coupled microwave resonators each containing a single superconducting qubit undergo sharp nonequilibrium delocalization-localization (self-trapping) transition due to strong photon-qubit coupling. find self-trapping of one the (spatial localization) forces opposite resonator remain its initial state (energetic localization). This allows for an easy experimental observation by local readout state. Dissipation and decoherence favor self-trapped regime.

We propose an inverse method to accelerate without final excitation the adiabatic transport of a Bose–Einstein condensate. The is based on partial extension Lewis–Riesenfeld invariants and provides protocols that satisfy exactly no-excitation conditions approximations. This complemented by optimizing trap trajectory with respect different physical criteria studying effect perturbations such as anharmonicities noise.

A current bottleneck for quantum computation is the realization of high-fidelity two-qubit operations between two or more bits in arrays coupled qubits. Gates based on parametrically driven tunable couplers offer a convenient method to entangle multiple qubits by selectively activating different interaction terms effective Hamiltonian. Here, we theoretically and experimentally study superconducting qubit setup with transmon connected via capacitively bus. We develop time-dependent...

We study the nonequilibrium steady state of driven-dissipative Bose-Hubbard model with Kerr nonlinearity. Employing a mean-field decoupling for intercavity hopping $J$, we find that steep crossover between low and high photon-density states inherited from single cavity transforms into gas--liquid bistability at large cavity-coupling $J$. formulate van der Waals--like phenomenology this setting determine relevant phase diagrams, including new type diagram where lobe-shaped boundary separates...

We study the interplay of geometric frustration and interactions in a nonequilibrium photonic lattice system exhibiting polariton flat band as described by variant Jaynes-Cummings-Hubbard model. show how to engineer strong correlations such driven, dissipative quenching kinetic energy through frustration. This produces an incompressible state photons characterized short-ranged crystalline order with period doubling. The latter manifests itself spatial correlations, i.e., on-site...

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

An array of high-Q electromagnetic resonators coupled to qubits gives rise the Jaynes-Cummings-Hubbard model describing a superfluid Mott insulator transition lattice polaritons. From mean-field and strong coupling expansions, critical properties are expected be identical scalar Bose-Hubbard model. A recent Monte Carlo study density on square suggested that this does not hold for fixed-density through lobe tip. Instead, behavior with dynamical exponent z=2 was found. We perform large-scale...

Photon-based strongly-correlated lattice models like the Jaynes-Cummings and Rabi lattices differ from their more conventional relatives Bose-Hubbard model by presence of an additional tunable parameter: frequency detuning between pseudo-spin degree freedom harmonic mode on each site. Whenever this is large compared to relevant coupling strengths, system said be in dispersive regime. The physics regime well-understood at level a single or Here, we extend theoretical description with many...

We calculate the location of quantum phase transitions a Bose gas trapped in an optical lattice as function effective scattering length a(eff) and temperature T. Knowledge recent high-loop results on shift critical at weak couplings is used to locate nose diagram above free Bose-Einstein T((0))(c), thus predicting existence reentrant transition where condensate should form when increasing a(eff). At zero temperature, normal produces experimentally observed Mott insulator.

We consider variants of the Jaynes-Cummings-Hubbard model lattice polaritons, taking into account next-nearest-neighbor, diagonal, and long-range photon hopping in one two dimensions. These models are relevant for potential experimental realizations polariton Mott insulators based on trapped ions or microwave stripline resonators. obtain Mott-superfluid phase boundary calculate excitation spectra using numerical analytical methods. Including additional terms leads to a larger case ions,...

We investigate the single-photon transport properties of a one-dimensional coupled cavity array (CCA) containing single qubit in its central site by coupling CCA to two transmission lines supporting propagating bosonic modes with linear dispersion. find that even nominally weak light-matter regime, through long exhibits ultra-narrow resonances corresponding long-lived, self-protected polaritonic states localized around qubit. The lifetime these is found increase exponentially number sites,...

We investigate the competition between superconductivity and ferromagnetism in chaotic ultrasmall metallic grains a regime where both phases can coexist. use an effective Hamiltonian that combines BCS-like pairing term ferromagnetic Stoner-like spin exchange term. study transport properties of grain Coulomb-blockade identify signatures coexistence correlations mesoscopic fluctuations conductance peak spacings heights.

We study the nonequilibrium steady-state of interacting photons in cavity arrays as described by driven-dissipative Bose–Hubbard and spin-1/2 XY model. For this purpose, we develop a self-consistent expansion inverse coordination number array () to solve Lindblad master equation these systems beyond mean-field approximation. Our formalism is compared benchmarked with exact numerical methods for small based on an diagonalization Liouvillian recently developed corner-space renormalization...

We investigate the two-photon scattering properties of a Jaynes-Cummings (JC) nonlinearity consisting two-level system (qubit) interacting with single-mode cavity, which is coupled to two waveguides, each containing single incident photon wave packet initially. In this setup, we study interplay between Hong-Ou-Mandel (HOM) effect arising due quantum interference and effective photon-photon interactions induced by presence qubit. calculate matrix analytically identify signatures interaction...

We propose a quantum simulator based on driven superconducting qubits where the interactions are generated parametrically by polychromatic magnetic flux modulation of tunable bus element. Using time-dependent Schrieffer-Wolff transformation, we analytically derive multi-qubit Hamiltonian which features independently $XX$ and $YY$-type as well local bias fields over large parameter range. demonstrate adiabatic simulation ground state hydrogen molecule using two one The time required to reach...

We investigate the competition between pairing correlations and ferromagnetism in small metallic grains presence of a Zeeman field. Our analysis is based on universal Hamiltonian, valid limit large Thouless conductance. show that coexistence regime superconducting ferromagnetic can be made experimentally accessible by tuning an external compare exact solution model with mean-field theory find latter cannot describe intermediate regime. also study occurrence spin jumps across phase boundary...

We propose a method to stop pulse of particles with different velocities by making them collide an accelerated wall trajectory $\ensuremath{\sim}\sqrt{t}$. Classical and quantum-mechanical cases are discussed, numerical simulations provided that show the efficiency method.