Non-Hermiticity-Governed Active Photonic Resonances

Rivero, Jose D. H.; Pan, Mingsen; Makris, Konstantinos G.; Feng, Liang; Li, Ge

doi:10.1103/physrevlett.126.163901

Cited by 18 publications

(4 citation statements)

References 47 publications

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“…Secondly, it may fail in systems where the addition of gain alter the nature of the modes (see for example Ref. [51]). In the present work, we have bridged this gap by systematically demonstrating how EPs can be accessed and tracked above the las- For reference, the EP from Ptot = 6.56µW is also indicated in all panels as a red diamond; the shift of the EP towards higher positive values of ∆P as Ptot is increased can be clearly observed.…”

Section: Discussionmentioning

confidence: 99%

Tracking exceptional points above laser threshold

El‐Ganainy

Yacomotti

et al. 2023

Preprint

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Recent studies on non-Hermitian optical systems having exceptional points (EPs) have revealed a host of unique characteristics associated with these singularities, including unidirectional invisibility, chiral mode switching and laser self-termination, to mention just a few examples. The vast majority of these works focused either on passive systems or active structures where the EPs were accessed below the lasing threshold, i.e. when the system description is inherently linear. In this work, we experimentally demonstrate that EP singularities in coupled semiconductor nanolasers can be accessed and tracked above the lasing threshold, where they become branch points of a nonlinear dynamical system. Contrary to the common belief that unavoidable cavity detuning will impede the formation of an EP, here we demonstrate that this same detuning is necessary for compensating the carrier-induced frequency shift, hence restoring the nonlinear EP in the lasing regime. Furthermore, unlike linear non-Hermitian systems, we find that the spectral location of EPs above laser threshold varies as a function of total pump power and can therefore be continuously tracked. Our work is a first step towards the realization of lasing EPs in more complex laser geometries, and enabling the enhancement of photonic local density of states through non-Hermitian symmetries combined with nonlinear interactions in coupled laser arrays.

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Section: Discussionmentioning

confidence: 99%

Tracking exceptional points above laser threshold

El‐Ganainy

Yacomotti

et al. 2023

Preprint

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“…Following the discoveries of non-Hermitian Hamiltonians in physical systems [27][28][29][30], a wealth of intriguing physical phenomena and applications have been explored [31][32][33][34][35][36][37][38][39][40][41][42][43][44]. In the non-Hermitian lattice system with nonreciprocity, the non-Hermitian skin effect (NHSE) describes the phenomenon of localization of eigenstates under the open boundary condition (OBC) [45].…”

Section: Introductionmentioning

confidence: 99%

Demonstration of reversed non-Hermitian skin effect via quantum walks on a ladder

Wang,

Xiao,

Lin

et al. 2023

New J. Phys.

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Quantum walks hold enormous potential applications in various areas such as quantum computing and quantum simulation. Discrete-time quantum walks on a ladder oﬀer greater prospects compared to traditional quantum walks, especially in addressing physical problems in higher-dimension coupled systems. Here we give an experimental proposal of quantum walks on a two-leg ladder using linear optics, and further apply it to non-Hermitian systems by introducing loss-based non-unitary evolutions. Non-Hermitian systems under nonreciprocity-induced evolution present an exotic phenomenon, known as the non-Hermitian skin eﬀect (NHSE). In a two-leg non-Hermitian system with the same preferred direction of NHSE, the direction has recently been found to reverse when interchain couplings are introduced. Based on quantum walks on a ladder, we also propose an experimentally feasible scheme to demonstrate the direction reversal of NHSE. Through the simulated results we show that particles on each chain accumulate to the preferred boundary driven by nonreciprocal hopping, while particles are transported in the opposite direction when interchain hopping is allowed, clearly demonstrating the existence of reversed NHSE. Our work further expands the application of the quantum walk platform and opens a door for the experimental investigation of reversed NHSE.

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“…In recent years, the interest in non-Hermitian optical structures has acquired a new dimension following a number of theoretical studies of parity-time (PT) symmetry in optics 5 – 7 and its first experimental demonstrations 8 , 9 . This in turn has initiated intense theoretical 10 – 39 , and experimental 40 – 58 investigations of non-Hermitian effects in photonic platforms. In contrast to earlier studies, the notion of EPs is at the heart of these recent works.…”

Section: Introductionmentioning

confidence: 99%

Linear response theory of open systems with exceptional points

et al. 2022

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Understanding the linear response of any system is the first step towards analyzing its linear and nonlinear dynamics, stability properties, as well as its behavior in the presence of noise. In non-Hermitian Hamiltonian systems, calculating the linear response is complicated due to the non-orthogonality of their eigenmodes, and the presence of exceptional points (EPs). Here, we derive a closed form series expansion of the resolvent associated with an arbitrary non-Hermitian system in terms of the ordinary and generalized eigenfunctions of the underlying Hamiltonian. This in turn reveals an interesting and previously overlooked feature of non-Hermitian systems, namely that their lineshape scaling is dictated by how the input (excitation) and output (collection) profiles are chosen. In particular, we demonstrate that a configuration with an EP of order M can exhibit a Lorentzian response or a super-Lorentzian response of order Ms with Ms = 2, 3, …, M, depending on the choice of input and output channels.

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Non-Hermiticity-Governed Active Photonic Resonances

Cited by 18 publications

References 47 publications

Tracking exceptional points above laser threshold

Tracking exceptional points above laser threshold

Demonstration of reversed non-Hermitian skin effect via quantum walks on a ladder

Linear response theory of open systems with exceptional points

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