Exceptional points in oligomer chains

Abstract

Symmetry underpins our understanding of physical law. Open systems, those in contact with their environment, can provide a platform to explore parity-time symmetry. While classical parity-time symmetric systems have received a lot of attention, especially because of the associated advances in the generation and control of light, there is much more to be discovered about their quantum counterparts. Here we provide a quantum theory which describes the non-Hermitian physics of chains of coupled modes, which has applications across optics and photonics. We elucidate the origin of the exceptional points which govern the parity-time symmetry, survey their signatures in quantum transport, study their influence for correlations, and account for long-range interactions. We also find how the locations of the exceptional points evolve as a function of the chain length and chain parity, capturing how an arbitrary oligomer chain transitions from its unbroken to broken symmetric phase. Our general results provide perspectives for the experimental detection of parity-time symmetric phases in one-dimensional arrays of quantum objects, with consequences for light transport and its degree of coherence.

Feedback and PT Symmetry in a class of Active LCR Circuits

“…The four exceptional points are easily obtained from ∂G(s) ∂s = 0 resulting in ±ω 0 and ±i ω 0 . These results agree with those presented in the literature [25]. As n → ∞, the oscillator chain tends to behave like a transmission line.…”

Analysis of Active LCR Circuits with PT Symmetry using Automatic Control Tools

“…7 (a), while (b) shows the corresponding plot of imaginary and real parts of the eigenvalues versus γ. This results agree with those presented in the literature [14]. The presented proposal allows a systematic approach to the analysis of quantum and classical systems where non-Hermiticity is present.…”

Resonance fluorescence of two asymmetrically pumped and coupled two-level systems

“…Our basic theory, spanning both coherent and incoherent coupling, may be realized in a plethora of artificial atom systems [86], including with ultracold atoms [87], superconducting qubits [88], and plasmonic nanoparticles [89,90]. The presented theory opens up the opportunity for the detection of cooperative Mollow physics and chiral physics within an elemental dimer system, with natural extensions.…”