References of "Braun, Daniel"
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See detailCooperative spontaneous emission from indistinguishable atoms in arbitrary motional quantum states
Damanet, François ULg; Braun, Daniel; Martin, John ULg

in Physical Review A (2016), 94

We investigate superradiance and subradiance of indistinguishable atoms with quantized motional states, starting with an initial total state that factorizes over the internal and external degrees of ... [more ▼]

We investigate superradiance and subradiance of indistinguishable atoms with quantized motional states, starting with an initial total state that factorizes over the internal and external degrees of freedom of the atoms. Due to the permutational symmetry of the motional state, the cooperative spontaneous emission, governed by a recently derived master equation [F. Damanet et al., Phys. Rev. A 93, 022124 (2016)], depends only on two decay rates γ and γ0 and a single parameter dd describing the dipole-dipole shifts. We solve the dynamics exactly for N = 2 atoms, numerically for up to 30 atoms, and obtain the large-N limit by a mean-field approach. We find that there is a critical difference γ0 − γ that depends on N beyond which superradiance is lost. We show that exact nontrivial dark states (i.e., states other than the ground state with vanishing spontaneous emission) only exist for γ = γ0 and that those states (dark when γ = γ0) are subradiant when γ < γ0. [less ▲]

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See detailMaster equation with quantized atomic motion including dipole-dipole interactions
Damanet, François ULg; Braun, Daniel; Martin, John ULg

Scientific conference (2016, May 26)

We derive a markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion [1]. Our equation provides a unifying ... [more ▼]

We derive a markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion [1]. Our equation provides a unifying picture of the consequences of recoil and in- distinguishability of atoms beyond the Lamb-Dicke regime on both their dissipative and conservative dynamics, and is relevant for experiments with ultracold trapped atoms. We give general expressions for the decay rates and the dipole-dipole shifts for any motional states, and we find analytical formulas for a number of relevant states (Gaussian states, Fock states and thermal states). In particular, we show that the dipole-dipole interactions and cooperative photon emission can be modulated through the external state of motion. The effects predicted should be experimen- tally observable with Rydberg atoms [2]. [1] F. Damanet, D. Braun, and J. Martin, arXiv:1512.06676v2. [2] K. Afrousheh, P. Bohlouli-Zanjani, D. Vagale, A. Mugford, M. Fedorov, and J. D. D. Martin, Phys. Rev. Lett. 93, 233001 (2004) [less ▲]

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See detailSuper- and subradiance from indistinguishable atoms with quantized motion
Damanet, François ULg; Braun, Daniel; Martin, John ULg

Poster (2016, May 18)

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See detailCollective spontaneous emission with quantized atomic motion
Damanet, François ULg; Braun, Daniel; Martin, John ULg

Scientific conference (2016, May 09)

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See detailMaster equation for collective spontaneous emission with quantized atomic motion
Damanet, François ULg; Braun, Daniel; Martin, John ULg

Scientific conference (2016, March 02)

We derive a markovian master equation for the internal dynamics of an ensemble of two-level atoms including the quantization of their motion. Our equation provides a unifying picture of the effects of ... [more ▼]

We derive a markovian master equation for the internal dynamics of an ensemble of two-level atoms including the quantization of their motion. Our equation provides a unifying picture of the effects of recoil and indistinguishability of atoms beyond the Lamb-Dicke regime on both their dissipative and conservative dynamics. We give general expressions for the decay rates and the dipole-dipole shifts for any motional states, generalizing those in Ref. [1]. We find closed-form formulas for a number of relevant states (gaussian states, Fock states and thermal states). In particular, we show that dipole-dipole interactions and cooperative photon emission [2] can be modulated through the external state of motion. As an application of our general formalism, we study the spatial Pauli blocking of two fermionic atoms beyond the Lamb-Dicke regime [3]. [1] G. S. Agarwal, Springer Tracts In Modern Physics 70, 1 (1974). [2] R. H. Dicke, Phys. Rev. 93, 99 (1954). [3] R. M. Sandner, M. Müller, A. J. Daley & P. Zoller, Phys. Rev. A 84, 043825 (2011). [less ▲]

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See detailMaster equation for collective spontaneous emission with quantized atomic motion
Damanet, François ULg; Braun, Daniel; Martin, John ULg

in Physical Review A (2016), 93

We derive a Markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion. Our equation provides a unifying ... [more ▼]

We derive a Markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion. Our equation provides a unifying picture of the consequences of recoil and indistinguishability of atoms beyond the Lamb-Dicke regime on both their dissipative and conservative dynamics, and applies equally well to distinguishable and indistinguishable atoms. We give general expressions for the decay rates and the dipole-dipole shifts for any motional states, and we find closed-form formulas for a number of relevant states (Gaussian states, Fock states, and thermal states). In particular, we show that dipole-dipole interactions and cooperative photon emission can be modulated through the external state of motion. [less ▲]

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See detailTensor Representation of Spin States
Giraud, Olivier; Braun, Daniel; Baguette, Dorian ULg et al

in Physical Review Letters (2015), 114

We propose a generalization of the Bloch sphere representation for arbitrary spin states. It provides a compact and elegant representation of spin density matrices in terms of tensors that share the most ... [more ▼]

We propose a generalization of the Bloch sphere representation for arbitrary spin states. It provides a compact and elegant representation of spin density matrices in terms of tensors that share the most important properties of Bloch vectors. Our representation, based on covariant matrices introduced by Weinberg in the context of quantum field theory, allows for a simple parametrization of coherent spin states, and a straightforward transformation of density matrices under local unitary and partial tracing operations. It enables us to provide a criterion for anticoherence, relevant in a broader context such as quantum polarization of light. [less ▲]

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See detailHeisenberg-limited metrology without entanglement
Braun, Daniel; Martin, John ULg

Conference (2012, March)

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See detailHeisenberg-limited Metrology without Entanglement
Braun, Daniel; Martin, John ULg

in Research in Optical Sciences, OSA Technical Digest (2012)

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See detailHeisenberg-limited metrology without entanglement
Braun, Daniel; Martin, John ULg

Conference (2012, January)

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See detailMultiqubit symmetric states with a high geometric entanglement
Martin, John ULg; Giraud, Olivier; Braun, Peter et al

Poster (2011, May 25)

We propose a detailed study of the geometric entanglement properties of pure symmetric N-qubit states, focusing more particularly on the identification of symmetric states with a high geometric ... [more ▼]

We propose a detailed study of the geometric entanglement properties of pure symmetric N-qubit states, focusing more particularly on the identification of symmetric states with a high geometric entanglement and how their entanglement behaves asymptotically for large N. We show that much higher geometric entanglement with improved asymptotical behavior can be obtained in comparison with the highly entangled balanced Dicke states studied previously. We also derive an upper bound for the geometric measure of entanglement of symmetric states. The connection with the quantumness of a state is discussed. [less ▲]

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See detailDecoherence-enhanced measurements
Braun, Daniel; Martin, John ULg

Conference (2009, May)

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See detailInterference in the light emitted by a single tunneling atom
Martin, John ULg; Braun, Daniel

Poster (2008, July)

Detailed reference viewed: 7 (1 ULg)
See detailSpontaneous emission from a tunneling atom
Braun, Daniel; Martin, John ULg

Conference (2008, March)

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See detailSpontaneous emission from a two-level atom tunneling in a double-well potential
Braun, Daniel; Martin, John ULg

in Physical Review. A (2008), 77

We study a two-level atom in a double-well potential coupled to a continuum of electromagnetic modes (black-body radiation in three dimensions at zero absolute temperature). Internal and external degrees ... [more ▼]

We study a two-level atom in a double-well potential coupled to a continuum of electromagnetic modes (black-body radiation in three dimensions at zero absolute temperature). Internal and external degrees of freedom of the atom couple due to recoil during emission of a photon. We provide a full analysis of the problem in the long wavelengths limit up to the border of the Lamb-Dicke regime, including a study of the internal dynamics of the atom (spontaneous emission), the tunneling motion, and the electric field of the emitted photon. The tunneling process itself may or may not decohere depending on the wavelength corresponding to the internal transition compared to the distance between the two wells of the external potential, as well as on the spontaneous emission rate compared to the tunneling frequency. Interference fringes appear in the emitted light from a tunneling atom, or an atom in a stationary coherent superposition of its center-of-mass motion, if the wavelength is comparable to the well separation, but only if the external state of the atom is post selected. [less ▲]

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See detailCoherent control of atomic tunnelling
Martin, John ULg; Braun, Daniel

in Journal of Physics B Atomic Molecular Physics (2008), 41

We study the tunnelling of a two-level atom in a double well potential while the atom is coupled to a single electromagnetic field mode of a cavity. The coupling between internal and external degrees of ... [more ▼]

We study the tunnelling of a two-level atom in a double well potential while the atom is coupled to a single electromagnetic field mode of a cavity. The coupling between internal and external degrees of freedom, due to the mechanical effect on the atom from photon emission into the cavity mode, can dramatically change the tunnelling behaviour. We predict that in general the tunnelling process becomes quasiperiodic. In a certain regime of parameters a collapse and revival of the tunnelling occurs. Accessing the internal degrees of freedom of the atom with a laser allows us to coherently manipulate the atom position, and in particular to prepare the atom in one of the two wells. [less ▲]

Detailed reference viewed: 27 (7 ULg)