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Lattice Gauge Tensor Networks

Thu, 2014-11-27 12:23 - Mattia Giardini
Date: 
2014-11-27
Author(s): 

P. Silvi, E. Rico, T. Calarco, S. Montangero

Reference: 

Journal reference: New J. Phys. 16 103015 (2014)
DOI: 10.1088/1367-2630/16/10/103015

URL: 

http://arxiv.org/abs/1404.7439

We present a unified framework to describe lattice gauge theories by means of tensor networks: this framework is efficient as it exploits the high amount of local symmetry content native of these systems describing only the gauge invariant subspace.

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

Thu, 2014-11-27 12:15 - Mattia Giardini
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]

URL: 

http://arxiv.org/abs/1402.0377

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.

Kronig-Penney model for ultracold atomic quantum systems

Thu, 2014-11-27 12:11 - Mattia Giardini
Date: 
2014-11-27
Author(s): 

A. Negretti, R. Gerritsma, Z. Idziaszek, F. Schmidt-Kaler, T. Calarco

Reference: 

Journal reference: Phys. Rev. B 90, 155426 (2014)
DOI: 10.1103/PhysRevB.90.155426
Cite as: arXiv:1406.6969 [quant-ph]

URL: 

http://arxiv.org/abs/1406.6969

We study the properties of a quantum particle interacting with a one dimensional structure of equidistant scattering centres. We derive an analytical expression for the dispersion relation and for the Bloch functions in the presence of both even and odd scattering waves within the pseudopotential approximation.

Optimal preparation of quantum states on an atom chip device

Thu, 2014-11-27 12:09 - Mattia Giardini
Date: 
2014-05-27 - 2014-11-27
Author(s): 

C. Lovecchio, F Schäfer, S Cherukattil, A K Murtaza, I Herrera, F S Cataliotti, T Calarco, S Montangero, F Caruso

Reference: 

arXiv:1405.6918

URL: 

http://arxiv.org/abs/1405.6918

Atom chips provide compact and robust platforms towards practical quantum technologies. A quick and faithful preparation of arbitrary input states for these systems is crucial but represents a very challenging experimental task. This is especially difficult when the dynamical evolution is noisy and unavoidable setup imperfections have to be considered.

Staying adiabatic with unknown energy gap

Thu, 2014-11-27 11:46 - Mattia Giardini
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.

Noise-resistant optimal spin squeezing via quantum control

Thu, 2014-11-27 11:12 - Mattia Giardini
Date: 
2014-04-26 - 2014-11-27
Author(s): 

T. Caneva, S. Montangero, M. D. Lukin, T. Calarco

Reference: 

arXiv:1304.7195v2

URL: 

http://arxiv.org/pdf/1304.7195v2.pdf

Entangled atomic states, such as spin squeezed states, represent a promising resource for a new generation of quantum sensors and atomic clocks. We demonstrate that optimal control techniques can be used to substantially enhance the degree of spin squeezing in strongly interacting many-body systems, even in the presence of noise and imperfections.

Towards experimental quantum field tomography with ultracold atoms

Thu, 2014-10-23 15:49 - Martin Kliesch
Date: 
2014-06-13 - 2014-10-23
Author(s): 

A. Steffens, M. Friesdorf, T. Langen, B. Rauer, T. Schweigler, R. Hübener, J. Schmiedmayer, C. A. Riofrío, J. Eisert

Reference: 

arXiv:1406.3632

URL: 

http://arxiv.org/abs/1406.3632

Matrix-Product Operators and States: NP-Hardness and Undecidability

Thu, 2014-10-23 15:23 - Martin Kliesch
Date: 
2014-10-16
Author(s): 

M. Kliesch, D. Gross, and J. Eisert

Reference: 

Phys. Rev. Lett. 113 (2014); DOI: http://dx.doi.org/10.1103/PhysRevLett.113.160503

URL: 

http://arxiv.org/abs/arXiv:1404.4466

Tensor network states constitute an important variational set of quantum states for numerical studies of strongly correlated systems in condensed-matter physics, as well as in mathematical physics. This is specifically true for finitely correlated states or matrix-product operators, designed to capture mixed states of one-dimensional quantum systems.

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