Two-atom system as a nanoantenna for mode switching and light routing

Lembessis, V. E.; Rsheed, Anwar Al; Aldossary, Omar M.; Ficek, Zbigniew

doi:10.1103/physreva.88.053814

Cited by 12 publications

(10 citation statements)

References 42 publications

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“…In contrast, driving from the opposite direction does not couple to the dark state at all. Based on these observations, we argue that the device should be understood as a saturable Yagi-Uda antenna (a directional dipole array) [11,14], and we speculate that non-reciprocity may be enhanced in an n > 2 atom device. This paper is organised as follows: We introduce the master equation describing the two atoms and the coherent drive via the waveguides in Section I and then start the analysis in Section II by calculating the steady-state of the two atoms under driving in the parameter regime relevant for rectification.…”

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confidence: 83%

“…They are typically used to route or isolate signals propagating in different directions. Recently, a unidirectional, two-atom device has been identified as potentially useful in quantum electronics [1][2][3][4][5][6][7], building on earlier analyses of distributed atomic systems [8][9][10][11][12]. Transmission through this device depends asymmetrically on the direction of the input field, hence it has been dubbed a quantum diode.…”

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confidence: 99%

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Nonreciprocal atomic scattering: A saturable, quantum Yagi-Uda antenna

et al. 2017

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Recent theoretical studies of a pair of atoms in a 1D waveguide find that the system responds asymmetrically to incident fields from opposing directions at low powers. Since there is no explicit time-reversal symmetry breaking elements in the device, this has caused some debate. Here we show that the asymmetry arises from the formation of a quasi-dark-state of the two atoms, which saturates at extremely low power. In this case the nonlinear saturability explicitly breaks the assumptions of the Lorentz reciprocity theorem. Moreover, we show that the statistics of the output field from the driven system can be explained by a very simple stochastic mirror model and that at steady state, the two atoms and the local field are driven to an entangled, tripartite |W state. Because of this, we argue that the device is better understood as a saturable Yagi-Uda antenna, a distributed system of differentially-tuned dipoles that couples asymmetrically to external fields.Nonreciprocal devices, such as isolators, circulators, and gyrators, are important components for optical and microwave technologies. They are typically used to route or isolate signals propagating in different directions. Recently, a unidirectional, two-atom device has been identified as potentially useful in quantum electronics [1][2][3][4][5][6][7], building on earlier analyses of distributed atomic systems [8][9][10][11][12]. Transmission through this device depends asymmetrically on the direction of the input field, hence it has been dubbed a quantum diode.The quantum diode consists of a pair of spatiallyseparated, nondegenerate atoms in a 1D waveguide, shown in Fig. 1a, tuned to discriminate between a coherent field α incident from the left, and a coherent field β incident from the right. Prima facie, this appears to violate reciprocity: the transmission coefficients of a passive, linear, time-reversal-symmetric scatterer should satisfy T ← = T → , so there is an interesting question as to the origin of the transmission asymmetry.Here, we derive a master equation for the driven twoatom system shown in Fig. 1a. We show that the twoatom dark state [7] responsible for the asymmetry arises from entanglement between the matter and the field [10]. This leads to non-reciprocal [13] and incoherent [7] scattering matrices, and we establish the maximum possible 'diode efficiency' [2] of 2/3, for which the steady state is inverted. Finally, we show that a toy-model of a randomly fluctuating mirror replicates the statistics of the scattered field and corresponds exactly to the rate equation model when adiabatically eliminating all coherences.The picture that emerges is that in the steady-state, under cw-driving from one direction, the two atoms become entangled with the local electromagnetic field in a tripartite |W state. In the atomic Hilbert space, this corresponds to a long-lived, probabilistic mixture of the ground and dark states. Since scattering arises from coherence between the ground and bright states, the dark * c.muller2@uq.edu.au † stace@physics.uq.edu...

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confidence: 83%

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confidence: 99%

Nonreciprocal atomic scattering: A saturable, quantum Yagi-Uda antenna

et al. 2017

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“…As we have shown in Ref. [21], for very short distances between the atoms their mutual interaction is very crucial for mode switching and routing. These can occur when the distance between the atoms is of the order of the wavelength of the laser radiation since in this case the interatomic dipole-dipole interaction is significant.…”

Section: Fig 1 (Color Online)mentioning

confidence: 73%

“…in which the block S is an 8 × 8 matrix of the coefficients of the eight equations involving the density matrix elements (20), block A is a 7 × 7 matrix of the coefficients of the seven equations involving the density matrix elements (21). The off-diagonal blocks B and D are 9 × 6 and 6 × 9 matrices whose nonzero elements are…”

Section: Equations Of Motion For the Density Matrix Elementsmentioning

confidence: 99%

“…Recently, we have developed a theory of directional emission for the somewhat related problem of directional light * vlempesis@ksu.edu.sa scattering by a system composed of two two-level atoms [21]. We have shown that the system can operate as a directional nanonantenna provided that the atoms are not identical with unequal transition dipole moments or different transition frequencies.…”

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confidence: 99%

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Radiation pattern of two identical emitters driven by a Laguerre-Gaussian beam: An atom nanoantenna

et al. 2015

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We study the directional properties of a radiation field emitted by a geometrically small system composed of two identical two-level emitters located at short distances and driven by an optical vortex beam, a LaguerreGaussian beam which possesses a structured phase and amplitude. We find that the system may operate as a nanoantenna for controlled and tunable directional emission. Polar diagrams of the radiation intensity are presented showing that a constant phase or amplitude difference at the positions of the emitters plays an essential role in the directivity of the emission. We find that the radiation patterns may differ dramatically for different phase and amplitude differences at the positions of the emitters. As a reults the system may operate as a two-or one-sided nanoantenna. In particular, a two-sided highly focused directional emission can be achieved when the emitters experience the same amplitude and a constant phase difference of the driving field. We find a general directional property of the emitted field that when the phase differences at the positions of the emitters equal an even multiple of π/4, the system behaves as a two-sided antenna. When the phase difference equals an odd multiple of π/4, the system behaves as an one-sided antenna. The case when the emitters experience the same phase but different amplitudes of the driving field is also considered and it is found that the effect of different amplitudes is to cause the system to behave as a uni-directional antenna radiating along the interatomic axis.

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Asymmetric coupling between two quantum emitters

et al. 2020

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We study a prototypical model of two coupled two-level systems, where the competition between coherent and dissipative coupling gives rise to a rich phenomenology. In particular, we analyze the case of asymmetric coupling, as well as the limiting case of chiral (or one-way) coupling. We investigate various quantum optical properties of the system, including its steady-state populations, power spectrum, and second-order correlation functions, and outline the characteristic features which emerge in each quantity as one sweeps through the nontrivial landscape of effective complex couplings. Most importantly, we reveal instances of population trapping, unexpected spectral features, and strong emission correlations.

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Two-atom system as a nanoantenna for mode switching and light routing

Cited by 12 publications

References 42 publications

Nonreciprocal atomic scattering: A saturable, quantum Yagi-Uda antenna

Nonreciprocal atomic scattering: A saturable, quantum Yagi-Uda antenna

Radiation pattern of two identical emitters driven by a Laguerre-Gaussian beam: An atom nanoantenna

Asymmetric coupling between two quantum emitters

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