05.80.+m Quantum information & complex systems

Exotic attractors of the non-equilibrium Rabi-Hubbard model

Date: 
2016-04-08
Author(s): 

M. Schiró, C. Joshi, M. Bordyuh, R. Fazio, J. Keeling, and H. E. Türeci

Reference: 

Phys. Rev. Lett. 116, 143603 (2016)

We explore the phase diagram of the dissipative Rabi-Hubbard model, as could be realized by a Raman-pumping scheme applied to a coupled cavity array. There exist various exotic attractors, including ferroelectric, antiferroelectric, and incommensurate fixed points, as well as regions of persistent oscillations. Many of these features can be understood analytically by truncating to the two lowest lying states of the Rabi model on each site. We also show that these features survive beyond mean field, using matrix product operator simulations.

Superfluid density and quasi-long-range order in the one-dimensional disordered Bose-Hubbard model

Date: 
2016-01-18
Author(s): 

M. Gerster, M. Rizzi, F. Tschirsich, P. Silvi, R. Fazio, S. Montangero

Reference: 

New J. Phys. 18, 015015 (2016)
http://dx.doi.org/10.1088/1367-2630/18/1/015015

We study the equilibrium properties of the one-dimensional disordered Bose–Hubbard model by means of a gauge-adaptive tree tensor network variational method suitable for systems with periodic boundary conditions. We compute the superfluid stiffness and superfluid correlations close to the superfluid to glass transition line, obtaining accurate locations of the critical points.

Full characterization of the quantum linear-zigzag transition

Date: 
2013-07-31
Author(s): 

P. Silvi, G. De Chiara, T. Calarco, G. Morigi, S. Montangero

Reference: 

Journal reference: Ann. Phys. 525, No. 10-11, 827-832 (2013)
DOI: 10.1002/andp.201300090

A string of repulsively interacting particles exhibits a phase transition to a zigzag structure, by reducing the transverse trap potential or the interparticle distance. The transition is driven by transverse, short wavelength vibrational modes.

Precise ultra fast single qubit control using optimal control pulses

Date: 
2014-09-01
Author(s): 

J. Scheuer, Xi Kong, R. S. Said, J. Chen, A. Kurz, L. Marseglia, J. Du, P. R. Hemmer, S. Montangero, T. Calarco, B. Naydenov, F. Jelezko

Reference: 

Journal reference: New J. Phys. 16, 093022 (2014)
DOI: 10.1088/1367-2630/16/9/093022

Ultra fast and accurate quantum operations are required in many modern scientific areas - for instance quantum information, quantum metrology and magnetometry. However the accuracy is limited if the Rabi frequency is comparable with the transition frequency due to the breakdown of the rotating wave approximation (RWA). Here we report the experimental implementation of a method based on optimal control theory, which does not suffer these restrictions.

Complexity of controlling quantum many-body dynamics

Date: 
2014-04-23
Author(s): 

T. Caneva, A. Silva, R. Fazio, S. Lloyd, T. Calarco, and S. Montangero

Reference: 

Journal reference: Phys. Rev. A 89, 042322 (2014)
DOI: http://dx.doi.org/10.1103/PhysRevA.89.042322

We demonstrate that arbitrary time evolutions of many-body quantum systems can be reversed even in cases when only part of the Hamiltonian can be controlled. The reversed dynamics obtained via optimal control --contrary to standard time-reversal procedures-- is extremely robust to external sources of noise.

Ab initio characterization of the quantum linear-zigzag transition using density matrix renormalization group calculations

Date: 
2014-03-10 - 2014-11-27
Author(s): 

P. Silvi, G. Morigi, T. Calarco, S. Montangero

Reference: 

Journal reference: Phys. Rev. B 89, 094103 (2014)
DOI: 10.1103/PhysRevB.89.094103

Ions of the same charge inside confining potentials can form crystalline structures which can be controlled by means of the ions density and of the external trap parameters. In particular, a linear chain of trapped ions exhibits a transition to a zigzag equilibrium configuration, which is controlled by the strength of the transverse confinement.

Interferometry with non-classical motional states of a Bose–Einstein condensate

Date: 
2014-05-30 - 2014-11-27
Author(s): 

S. van Frank, A. Negretti, T. Berrada, R. Bücker, S. Montangero, J.-F.
Schaff, T. Schumm, T. Calarco, J. Schmiedmayer

Reference: 

Journal reference: Nature Communications 5, 4009 (2014)
DOI: 10.1038/ncomms5009
Cite as: arXiv:1402.0377 [quant-ph]

We demonstrate a two-pulse Ramsey-type interferometer for non-classical motional states of a Bose-Einstein condensate in an anharmonic trap. The control pulses used to manipulate the condensate wavefunction are obtained from Optimal Control Theory and directly optimised to maximise the interferometric contrast.

Staying adiabatic with unknown energy gap

Date: 
2014-11-27
Author(s): 

J. Nehrkorn, S. Montangero, A. Ekert, A. Smerzi, R. Fazio, T. Calarco

Reference: 

arXiv:1105.1707v1

We introduce an algorithm to perform an optimal adiabatic evolution that operates without an apriori knowledge of the system spectrum. By probing the system gap locally, the algorithm maximizes the evolution speed, thus minimizing the total evolution time.

Realistic and verifiable coherent control of excitonic states in a light harvesting complex

Date: 
2013-07-18 - 2014-01-20
Author(s): 

Stephan Hoyer, Filippo Caruso, Simone Montangero, Mohan Sarovar, Tommaso Calarco, Martin B. Plenio and K. Birgitta Whaley

Reference: 

New Journal of Physics 16, 045007 (2014)

We explore the feasibility of coherent control of excitonic dynamics in light harvesting complexes, analyzing the limits imposed by the open nature of these quantum systems. We establish feasible targets for phase and phase/amplitude control of the electronically excited state populations in the Fenna-Mathews-Olson (FMO) complex and analyze the robustness of this control with respect to orientational and energetic disorder, as well as decoherence arising from coupling to the protein environment.

Syndicate content