Result

Nonlinear quantum optics mediated by Rydberg interactions

Date: 
2016-06-30
Author(s): 

D. S. Ding, C. S. Adams, B. S. Shi, G. C. Guo

Reference: 

J. Phys. B: At. Mol. Opt. Phys. 49 (2016) 152003

URL: 

10.1088/0953-4075/49/15/152003

By mapping the strong interaction between Rydberg excitations in ultra-cold atomic ensembles onto single photons via electromagnetically induced transparency, it is now possible to realize a medium which exhibits a strong optical nonlinearity at the level of individual photons. We review the theoretical concepts and the experimental state-of-the-art of this exciting new field, and discuss first applications in the field of all-optical quantum information processing.

Tunable cw UV laser with <35 kHz absolute frequency instability for precision spectroscopy of Sr Rydberg states

Date: 
2016-01-28
Author(s): 

Elizabeth M. Bridge, Niamh C. Keegan, Alistair D. Bounds, Danielle Boddy, Daniel P. Sadler, and Matthew P. A. Jones

Reference: 

Opt. Express 24, 2281-2292 (2016)

URL: 

10.1364/OE.24.002281

We present a solid-state laser system that generates over 200 mW of continuous-wave, narrowband light, tunable from 316.3 nm – 317.7 nm and 318.0 nm – 319.3 nm.

Difference-frequency combs in cold atom physics

Date: 
2016-05-04
Author(s): 

Russell Kliese, Nazanin Hoghooghi, Thomas Puppe, Felix Rohde, Alexander Sell, Armin Zach, Patrick Leisching, Wilhelm Kaenders, Niamh C. Keegan, Alistair D. Bounds, Elizabeth M. Bridge, Jack Leonard, Charles S. Adams, Simon L. Cornish, Matthew P. A. Jones

Reference: 

Eur. Phys. J. Special Topics 225, 2775–2784 (2016)

URL: 

10.1140/epjst/e2016-60092-0

Optical frequency combs provide the clockwork to relate optical frequencies
to radio frequencies. Hence, combs allow to measure optical frequencies
with respect to a radio frequency where the accuracy is limited
only by the reference signal. In order to provide a stable link between the
radio and optical frequencies, the two parameters of the frequency comb
must be fixed: the carrier envelope offset frequency fceo and the pulse

Rydberg dressing of a one-dimensional Bose-Einstein condensate

Date: 
2016-05-14
Author(s): 

Marcin Płodzień, Graham Lochead, N. J. van Druten, and Servaas Kokkelmans

Reference: 

arXiv:1605.04440 [cond-mat.quant-gas]

We study the influence of Rydberg dressed interactions in a one-dimensional (1D) Bose-Einstein Condensate (BEC). We show that 1D is advantageous over 3D for observing BEC Rydberg dressing. The effects of dressing are studied by investigating collective BEC dynamics after a rapid switch-off of the Rydberg dressing interaction. The results can be interpreted as an effective modification of the $s$-wave scattering length.

Raman transitions between hyperfine clock states in a magnetic trap

Date: 
2016-07-27
Author(s): 

J. B. Naber, L. Torralbo-Campo, T. Hubert, and R. J. C. Spreeuw

Reference: 

Phys. Rev. A 94, 013427 (2016)

We present our experimental investigation of an optical Raman transition between the magnetic clock states of $^87$Rb in an atom chip magnetic trap. The transfer of atomic population is induced by a pair of diode lasers which couple the two clock states off-resonantly to an intermediate state manifold.

Electromagnetically induced transparency with Rydberg atoms across the Breit-Rabi regime

Date: 
2017-04-25
Author(s): 

J. B. Naber, A. Tauschinsky, van Linden van den Heuvell, and R. J. C. Spreeuw

Reference: 

SciPost Phys. 2, 015 (2017)

We present experimental results on the influence of magnetic fields and laser polarization on electromagnetically induced transparency (EIT) using Rydberg levels of $^87$Rb atoms. The measurements are performed in a room temperature vapor cell with two counter-propagating laser beams at 480nm and 780nm in a ladder-type energy level scheme.

Fermionic orbital optimisation in tensor network states

Date: 
2015-04-01 - 2016-06-20
Author(s): 

C. Krumnow, L. Veis, Ö. Legeza, J. Eisert

Reference: 

arXiv:1504.00042

Tensor network states and specifically matrix-product states have proven to be a powerful tool for simulating ground states of strongly correlated spin models. Recently, they have also been applied to interacting fermionic problems, specifically in the context of quantum chemistry.

Uncertainty Quantification for Matrix Compressed Sensing and Quantum Tomography Problems

Date: 
2015-04-01 - 2016-06-20
Author(s): 

Alexandra Carpentier, Jens Eisert, David Gross, Richard Nickl

Reference: 

arXiv:1504.03234

We construct minimax optimal non-asymptotic confidence sets for low rank matrix recovery algorithms such as the Matrix Lasso or Dantzig selector.

Improving compressed sensing with the diamond norm

Date: 
2015-11-01 - 2016-06-20
Author(s): 

Martin Kliesch, Richard Kueng, Jens Eisert, David Gross

Reference: 

arXiv:1511.01513

In low-rank matrix recovery, one aims to reconstruct a low-rank matrix from a minimal number of linear measurements. Within the paradigm of compressed sensing, this is made computationally efficient by minimizing the nuclear norm as a convex surrogate for rank. In this work, we identify an improved regularizer based on the so-called diamond norm, a concept imported from quantum information theory.

Fault tolerant dynamical decoders for topological quantum memories

Date: 
2015-11-01 - 2016-06-20
Author(s): 

M. Herold, M. J. Kastoryano, E. T. Campbell, J. Eisert

Reference: 

arXiv:1511.05579

Active error correction of topological quantum codes - in particular the toric code - remains one of the most viable routes to large scale quantum information processing. In this work, we introduce the concept of a dynamical decoder as a promising route for achieving fault-tolerant quantum memories.

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