QIPC

Hexagonal Plaquette Spin-spin Interactions and Quantum Magnetism in a Two-dimensional Ion Crystal

Date: 
2015-04-07
Author(s): 

Rejish Nath, Marcello Dalmonte, Alexander W Glaetzle, Peter Zoller, Ferdinand Schmidt-Kaler, Rene Gerritsma

Reference: 

New J. Phys. 17 (2015) 065018

We propose a trapped ion scheme en route to realize spin Hamiltonians on a Kagome lattice which, at low energies, are described by emergent Z2 gauge fields, and support a topological quantum spin liquid ground state. The enabling element in our scheme is the hexagonal plaquette spin-spin interactions in a 2D ion crystal. For this, the phonon-mode spectrum of the crystal is engineered by standing-wave optical potentials or by using Rydberg excited ions, thus generating localized phonon-modes around a hexagon of ions selected out of the entire two-dimensional crystal.

Observation of chiral edge states with neutral fermions in synthetic Hall ribbons

Date: 
2015-02-09
Author(s): 

M. Mancini, G. Pagano, G. Cappellini, L. Livi, M. Rider, J. Catani, C. Sias, P. Zoller, M. Inguscio, M. Dalmonte, L. Fallani

Reference: 

Science 349, 1510 (2015).

Chiral edge states are a hallmark of quantum Hall physics. In electronic systems, they appear as a macroscopic consequence of the cyclotron orbits induced by a magnetic field, which are naturally truncated at the physical boundary of the sample. Here we report on the experimental realization of chiral edge states in a ribbon geometry with an ultracold gas of neutral fermions subjected to an artificial gauge field.

Cluster Luttinger liquids and emergent supersymmetric conformal critical points in the one-dimensional soft-shoulder Hubbard model

Date: 
2016-06-07
Author(s): 

M. Dalmonte, W. Lechner, Zi Cai, M. Mattioli, A. M. Läuchli, G. Pupillo

Reference: 

Phys. Rev. B 92, 045106 (2015).

We investigate the quantum phases of hard-core bosonic atoms in an extended Hubbard model where particles interact via soft-shoulder potentials in one dimension. Using a combination of field-theoretical methods and strong-coupling perturbation theory, we demonstrate that the low-energy phase can be a conformal cluster Luttinger liquid (CLL) phase with central charge c=1, where the microscopic degrees of freedom correspond to mesoscopic ensembles of particles. Using numerical density-matrix-renormalization-group methods, we demonstrate that the CLL phase, first predicted in [Phys. Rev. Lett.

Dipolar spin models with arrays of superconducting qubits

Date: 
2015-01-13
Author(s): 

M. Dalmonte, S.I. Mirzai, P.R. Muppalla, D. Marcos, P. Zoller, G. Kirchmair

Reference: 

Phys. Rev. B 92, 174507 (2015).

We propose a novel platform for quantum many body simulations of dipolar spin models using current circuit QED technology. Our basic building blocks are 3D Transmon qubits where we use the naturally occurring dipolar interactions to realize interacting spin systems. This opens the way toward the realization of a broad class of tunable spin models in both two- and one-dimensional geometries.

Chains with loops - synthetic magnetic fluxes and topological order in one-dimensional spin systems

Date: 
2014-12-18
Author(s): 

Tobias Grass, Christine Muschik, Alessio Celi, Ravindra Chhajlany, Maciej Lewenstein

Reference: 

Phys. Rev. A 91, 063612 (2015).

Engineering topological quantum order has become a major field of physics. Many advances have been made by synthesizing gauge fields in cold atomic systems. Here, we carry over these developments to other platforms which are extremely well suited for quantum engineering, namely trapped ions and nano-trapped atoms. Since these systems are typically one-dimensional, the action of artificial magnetic fields has so far received little attention. However, exploiting the long-range nature of interactions, loops with non-vanishing magnetic fluxes become possible even in one-dimensional settings.

Many-body localization and quantum ergodicity in disordered long-range Ising models

Date: 
2014-10-06
Author(s): 

Philipp Hauke, Markus Heyl

Reference: 

Phys. Rev. B 92, 134204 (2015).

Ergodicity in quantum many-body systems is - despite its fundamental importance - still an open problem. Many-body localization provides a general framework for quantum ergodicity, and may therefore offer important insights. However, the characterization of many-body localization through simple observables is a difficult task. In this article, we introduce a measure for distances in Hilbert space for spin-1/2 systems that can be interpreted as a generalization of the Anderson localization length to the many-body Hilbert space.

Lattice gauge theories simulations in the quantum information era

Date: 
2016-02-11 - 2016-06-07
Author(s): 

M. Dalmonte, S. Montangero

Reference: 

Cont. Phys. (2016), 1-25

The many-body problem is ubiquitous in the theoretical description of physical phenomena, ranging from the behavior of elementary particles to the physics of electrons in solids. Most of our understanding of many-body systems comes from analyzing the symmetry properties of Hamiltonian and states: the most striking example are gauge theories such as quantum electrodynamics, where a local symmetry strongly constrains the microscopic dynamics.

Quantum simulation of the dynamical casimir effect with trapped ions

Date: 
2015-12-03 - 2016-06-07
Author(s): 

Nils Trautmann, Philipp Hauke

Reference: 

New J Phys. 18, 043029 (2016).

Quantum vacuum fluctuations are a direct manifestation of Heisenberg's uncertainty principle. The dynamical Casimir effect allows for the observation of these vacuum fluctuations by turning them into real, observable photons. However, the observation of this effect in a cavity QED experiment would require the rapid variation of the length of a cavity with relativistic velocities, a daunting challenge. Here, we propose a quantum simulation of the dynamical Casimir effect using an ion chain confined in a segmented ion trap.

Photonic quantum circuits with finite time delays

Date: 
2015-10-15 - 2016-06-07
Author(s): 

Hannes Pichler, Peter Zoller

Reference: 

Phys. Rev. Lett. 116, 093601 (2016).

We study the dynamics of photonic quantum circuits consisting of nodes coupled by quantum channels. We are interested in the regime where time delay in communication between the nodes is significant. This includes the problem of quantum feedback, where a quantum signal is fed back on a system with a time delay. We develop a matrix product state approach to solve the Quantum Stochastic Schrödinger Equation with time delays, which accounts in an efficient way for the entanglement of nodes with the stream of emitted photons in the waveguide, and thus the non-Markovian character of the dynamics.

Measuring multipartite entanglement via dynamic susceptibilities

Date: 
2015-09-05 - 2016-06-07
Author(s): 

Philipp Hauke, Markus Heyl, Luca Tagliacozzo, Peter Zoller

Reference: 

Nature Physics, advance online pubication

Entanglement plays a central role in our understanding of quantum many body physics, and is fundamental in characterising quantum phases and quantum phase transitions. Developing protocols to detect and quantify entanglement of many-particle quantum states is thus a key challenge for present experiments. Here, we show that the quantum Fisher information, representing a witness for genuinely multipartite entanglement, becomes measurable for thermal ensembles via the dynamic susceptibility, i.e., with resources readily available in present cold atomic gas and condensed-matter experiments.

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