15.20.Ca Cavity QED

Feedback control of a single atom in an optical cavity

Date: 
2011-02-12
Author(s): 

A. Kubanek, M. Koch, C. Sames, A. Ourjoumtsev, T. Wilk, P.W.H. Pinkse, G. Rempe

Reference: 

Applied Physics B 102, 433 (2011)
doi: 10.1007/s00340-011-4410-x

We discuss feedback control of the motion of a single neutral atom trapped inside a high-finesse optical cavity. Based on the detection of single photons from a probe beam transmitted through the cavity, the position of the atom in the trap is estimated. Following this information, the trapping potential is switched between a high and a low value in order to counteract the atomic motion. This allowed us to increase the storage time by about one order of magnitude.

Three-Photon Correlations in a Strongly Driven Atom-Cavity System

Date: 
2011-07-06
Author(s): 

M. Koch, C. Sames, M. Balbach, H. Chibani, A. Kubanek, K. Murr, T. Wilk, G. Rempe

Reference: 

Physical Review Letters 107, 023601 (2011)

The quantum dynamics of a strongly driven, strongly coupled single-atom-cavity system is studied by evaluating time-dependent second- and third-order correlations of the emitted photons. The coherent energy exchange, first, between the atom and the cavity mode, and second, between the atom-cavity system and the driving laser, is observed. Three-photon detections show an asymmetry in time, a consequence of the breakdown of detailed balance. The results are in good agreement with theory and are a first step towards the control of a quantum trajectory at larger driving strength.

Phase transitions and Heisenberg limited metrology in an Ising chain interacting with a single-mode cavity field

Date: 
2011-05-19
Author(s): 

S Gammelmark and K. Mølmer

Reference: 

New J. Phys. 13 053035 (2011)

We investigate the thermodynamics of a combined Dicke and Ising model that exhibits a rich phenomenology arising from the second-order and quantum phase transitions from the respective models. The partition function is calculated using mean-field theory, and the free energy is analyzed in detail to determine the complete phase diagram of the system.

Single-atom cavity QED and optomicromechanics

Date: 
2010-02-18
Author(s): 

M. Wallquist, K. Hammerer, p. Zoller, C. Genes, M. Ludwig, F. Marquardt, P. Treutlein, J. Ye, H.J. Kimble

Reference: 

Phys. Rev. A 81 023816 (2010)

In a recent publication [K. Hammerer, M. Wallquist, C. Genes, M. Ludwig, F. Marquardt, P. Treutlein, P. Zoller, J. Ye, and H. J. Kimble, Phys. Rev. Lett. 103, 063005 (2009)] we have shown the possibility to achieve strong coupling of the quantized motion of a micron-sized mechanical system to the motion of a single trapped atom. In the proposed setup the coherent coupling between a SiN membrane and a single atom is mediated by the field of a high finesse cavity and can be much larger than the relevant decoherence rates.

Analyzing quantum jumps of one and two atoms strongly coupled to an optical cavity

Date: 
2010-05-07
Author(s): 

S. Reick, K. Mølmer, W. Alt, M. Eckstein, T. Kampschulte, L. Kong, R. Reimann, A. Thobe, A. Widera, D. Meschede

Reference: 

Journal Opt. Soc. Am. B 27, A152 (2010)

We induce quantum jumps between the hyperfine ground states of one and two cesium atoms, strongly coupled to the mode of a high-finesse optical resonator, and analyze the resulting random telegraph signals. We identify experimental parameters to deduce the atomic spin state non destructively from the stream of photons transmitted through the cavity, achieving a compromise between a good signal-to-noise ratio and minimal measurement-induced perturbations.

Optically Levitating Dielectrics in the Quantum Regime: Theory and Protocols

Date: 
2010-10-15
Author(s): 

O. Romero-Isart, A. C. Pflanzer, M. L. Juan, R. Quidant, N. Kiesel, M. Aspelmeyer, J. I. Cirac

Reference: 

Phys. Rev. A 83, 013803 (2011)

We provide a general quantum theory to describe the coupling of light with the motion of a dielectric object inside a high finesse optical cavity. In particular, we derive the total Hamiltonian of the system as well as a master equation describing the state of the center of mass mode of the dielectric and the cavity field mode. In addition, a quantum theory of elasticity is used in order to study the coupling of the center of mass motion with internal vibrational excitations of the dielectric.

Entanglement of two individual atoms using the Rydberg blockade

Date: 
2010-06-07 - 2010-06-12
Author(s): 

A. Browaeys, A. Gaetan, T. Wilk, C. Evellin, J. Wolters, Y. Miroshnychenko, P. Grangier, P. Pillet, D. Comparat, A. Chotia, and M. Viteau

Reference: 

19th International Conference on Laser Spectroscopy, Kussharo, JAPAN, JUN 07-12, 2009, in:Laser Spectroscopy, 63-73 (2010)

We report on our recent progress on the manipulation of single rubidium atoms trapped in optical tweezers and the generation of entanglement between two atoms, each individually trapped in neighboring tweezers. To create an entangled state of two atoms in their ground states, we make use of the Rydberg blockade mechanism. The degree of entanglement is measured using global rotations of the internal states of both atoms. Such internal state rotations on a single atom are demonstrated with a high fidelity.

Analysis of the entanglement between two individual atoms using global Raman rotations

Date: 
2010-06-28
Author(s): 

A. Gaetan, C. Evellin, J. Wolters, P. Grangier, T. Wilk, and A. Browaeys

Reference: 

New Journal of Physics, 12, 12 (2010)

Making use of the Rydberg blockade, we generate entanglement between two atoms individually trapped in two optical tweezers. In this paper we detail the analysis of the data and show that we can determine the amount of entanglement between the atoms in the presence of atom losses during the entangling sequence. Our model takes into account states outside the qubit basis and allows us to perform a partial reconstruction of the density matrix describing the two atom state.

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