6.2 Superradiance

Benedict, M. G.; Trifonov, E. D.

doi:10.1007/978-3-540-47008-3_4

Cited by 4 publications

(3 citation statements)

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“…Subradiant states of a system of two-level atoms [1][2][3][4][5] has recently gained wide attention because of their exceptionally slow decoherence [6][7][8]. This stability of quantum superpositions inside the subradiant subspaces originates from the low probability of photon emission, which means very weak interaction between the atoms and their environment.…”

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confidence: 99%

Preparation of decoherence-free, subradiant states in a cavity

2002

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The cause of decoherence in a quantum system can be traced back to the interaction with the environment. As it has been pointed out first by Dicke, in a system of N two-level atoms where each of the atoms is individually dipole coupled to the environment, there are collective, subradiant states, that have no dipole coupling to photon modes, and therefore they are expected to decay slower. This property also implies that these type of states, which form an N − 1 dimensional subspace of the atomic subsytem, also decohere slower. We propose a scheme which will create such states. First the two-level atoms are placed in a strongly detuned cavity and one of the atoms, called the control atom is excited. The time evolution of the coupled atom-cavity system leads to an appropriately entangled state of the atoms. By applying subsequent laser pulses at a well defined time instant, it is possible to drive the atomic state into the subradiant, i. e., decoherence free subspace. Up to a certain average number of the photons, the result is independent of the state of the cavity. The analysis of the conditions shows that this scheme is feasible with present day techniques achieved in atom cavity interaction experiments.PACS: 42.50.Fx, 03.67.LxSubradiant states of a system of two-level atoms [1][2][3][4][5] has recently gained wide attention because of their exceptionally slow decoherence [6][7][8]. This stability of quantum superpositions inside the subradiant subspaces originates from the low probability of photon emission, which means very weak interaction between the atoms and their environment. Hence the subradiant states span a decoherence-free subspace (DFS) [9][10][11] of the atomic Hilbert-space and consequently can become important from the viewpoint of quantum computation (QC) [10,12]. The scheme we propose can be used to prepare subradiant states in a cavity. Our method is based on second order perturbation theory but the exact results verify the validity of the perturbative approach. We also investigate to what extent our scheme is independent of the state of the cavity field. Finally the requirements needed to prepare subradiant states in the proposed way will be compared with available experimental techniques [13][14][15][16].We investigate a system of N identical two-level atoms in a single mode cavity. Each individual atom is equivalent to a spin-1/2 system, and the whole atomic ensemble can be described by the aid of collective atomic operators J + , J − and J z obeying the same algebra as the usual angular momentum operators [1]. We consider the following model Hamiltonian:where a and a † are the annihilation and creation operators of the cavity mode, ω a is the transition frequency between the two atomic energy levels, ω c denotes the frequency of the cavity mode, different from ω a , and g is the coupling constant. We note that the Hamiltonian (1) is written in the framework of Dicke's theory, i.e., with the assumption that all the atoms are subjected to the same field, which is a good approximation when th...

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Preparation of decoherence-free, subradiant states in a cavity

2002

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“…The spontaneous emission of atoms can be enhanced or inhibited in several ways. One way to modify the spontaneous emission rate is through dipoledipole interactions between different atoms, namely sub-and superradiance-type effects [8][9][10][11]. This has been extensively studied in neutral atom systems and used for diverse applications (see for example Refs.…”

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confidence: 99%

The Panopticon device: an integrated Paul-trap-hemispherical mirror system for quantum optics

Araneda,

Cerchiari,

Higginbottom

et al. 2020

Preprint

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We present the design and construction of a new experimental apparatus for the trapping of a single Ba + ion in the center of curvature of an optical-quality hemispherical mirror. We describe the layout, fabrication and integration of the full setup, consisting of a high-optical access monolithic '3D-printed' Paul trap, the hemispherical mirror, a diffraction-limited in-vacuum lens (NA = 0.7) for collection of atomic fluorescence and a state-of-the art UHV vessel. This new apparatus enables the study of quantum electrodynamics effects such as strong inhibition and enhancement of spontaneous emission, and achieves a collection efficiency of the emitted light in a single optical mode of 38 %.

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“…time of a photon travelling through the plasmonic waveguidetg T l v  ,and the characteristic decay time of collective processes (superradiance) given by[56] is the group velocity of a photon inside the waveguide, n N Al  is the concentration of emitters per unit volume and μ is the electric dipole moment. In our work, we assumed that N = 100 emitters are embedded in the plasmonic waveguide channel with length l and slit area A ( lA  ).…”

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Controlling collective spontaneous emission with plasmonic waveguides

Liu¹,

Argyropoulos²

2016

Opt. Express

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Abstract:We demonstrate a plasmonic route to control the collective spontaneous emission of two-level quantum emitters. Superradiance and subradiance effects are observed over distances comparable to the operating wavelength inside plasmonic nanochannels. These plasmonic waveguides can provide an effective epsilon-near-zero operation in their cut-off frequency and Fabry-Pérot resonances at higher frequencies. The related plasmonic resonant modes are found to efficiently enhance the constructive (superradiance) or destructive (subradiance) interference between different quantum emitters located inside the waveguides. By increasing the number of emitters located in the elongated plasmonic channel, the superradiance effect is enhanced at the epsilon-near-zero operation, leading to a strong coherent increase in the collective spontaneous emission rate. In addition, the separation distance between neighboring emitters and their emission wavelengths can be changed to dynamically control the collective emission properties of the plasmonic system. It is envisioned that the dynamic modification between quantum superradiant and subradiant modes will find applications in quantum entanglement of qubits, low-threshold nanolasers and efficient sensors. References and links 1.E. M. Purcell, "Spontaneous emission probabilities at radio frequencies.," Phys.

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6.2 Superradiance

Cited by 4 publications

References 50 publications

Preparation of decoherence-free, subradiant states in a cavity

Preparation of decoherence-free, subradiant states in a cavity

The Panopticon device: an integrated Paul-trap-hemispherical mirror system for quantum optics

Controlling collective spontaneous emission with plasmonic waveguides

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