-symmetric photonic quantum systems with gain and loss do not exist

  title={-symmetric photonic quantum systems with gain and loss do not exist},
  author={S. Scheel and Alexander Szameit},
  journal={Europhysics Letters},
We discuss the impact of gain and loss on the evolution of photonic quantum states and find that -symmetric quantum optics in gain/loss systems is not possible. Within the framework of macroscopic quantum electrodynamics we show that gain and loss are associated with non-compact and compact operator transformations, respectively. This implies a fundamentally different way in which quantum correlations between a quantum system and a reservoir are built up and destroyed. 

Measurement of photon correlations in PT-symmetric systems

We investigate quantum interference in a PT -symmetric system by measuring a Hong-Ou-Mandel-Dip in waveguide couplers. The nontrivial loss distribution giving rise to PT-symmetry systematically

Quantum Behavior of a PT -Symmetric Two-Mode System with Cross-Kerr Nonlinearity

Quantum behavior of two oscillator modes, with mutually balanced gain and loss and coupled via linear coupling (including energy conserving as well as energy non-conserving terms) and nonlinear

Anti-Parity-Time Symmetric Optical Four-Wave Mixing in Cold Atoms.

It is observed that the pair of frequency modes undergo a nontrivial anti-PT phase transition between coherent power oscillation and optical parametric amplification in presence of a large phase mismatch.

Passive PT -symmetric Floquet coupler

Based on a Liouville-space formulation of open systems, we present a solution to the quantum master equation of two coupled optical waveguides with varying loss. The periodic modulation of the

Quantum correlations in PT -symmetric systems

We study the dynamics of correlations in a paradigmatic setup to observe PT -symmetric physics: a pair of coupled oscillators, one subject to a gain one to a loss. Starting from a coherent state,

Observation of PT-symmetric quantum interference

A common wisdom in quantum mechanics is that the Hamiltonian has to be Hermitian in order to ensure a real eigenvalue spectrum. Yet, parity–time (PT)-symmetric Hamiltonians are sufficient for real

Quantum description of a PT-symmetric nonlinear directional coupler

We treat a PT-symmetric directional coupler with Kerr nonlinearity in both the single-mode waveguides. We investigate the quantum propagation of a coherent state through this device and simplify the

Virtual Parity-Time Symmetry.

This work implements PT symmetry in the complex-frequency plane and realizes its landmark effects, such as broken phase transitions, anisotropic transmission resonances, and laser-absorber pairs, in a fully passive system, opening a path to establish PT symmetry and non-Hermitian physics in passive platforms.

Effects of Non-Hermitian Bilayer Medium on the Second-Order Coherence of the Transmitted Coherent and Number States

A BSTRACT — We investigate the propagation of the normal two-photon number state and coherent state of light through a dispersive non-Hermitian bilayer structure composed of gain and loss layers,

Optical Energy-difference Conservation in a Synthetic Anti-PT Symmetric System

This work creates an optical APT-symmetric system in a synthetic frequency domain using a conventional fiber without intrinsic gain or loss and experimentally reveals photonic APTs, including energy-difference conservation and synchronized power oscillation, which have not yet been confirmed experimentally in the optical domain.



Spontaneous generation of photons in transmission of quantum fields inPT-symmetric optical systems

We develop a rigorous mathematically consistent description of PT symmetric optical systems by using second quantization. We demonstrate the possibility of significant spontaneous generation of

Quantum noise and self-sustained radiation of PT-symmetric systems.

This work shows that microreversibility-breaking quantum noise turns PT-symmetric systems into self-sustained sources of radiation, which distinguishes them from ordinary, Hermitian quantum systems.

Observation of PT-symmetry breaking in complex optical potentials.

This work demonstrates experimentally passive PT-symmetry breaking within the realm of optics, which leads to a loss induced optical transparency in specially designed pseudo-Hermitian guiding potentials.

Beam dynamics in PT symmetric optical lattices.

It is shown that PT periodic structures can exhibit unique characteristics stemming from the nonorthogonality of the associated Floquet-Bloch modes, including double refraction, power oscillations, and eigenfunction unfolding as well as nonreciprocal diffraction patterns.

Topologically protected bound states in photonic parity-time-symmetric crystals.

This work shows theoretically and experimentally the existence of states that are localized at the interface between two topologically distinct PT-symmetric photonic lattices, and finds analytical closed form solutions of topological PT-Symmetric interface states.

Parity–time synthetic photonic lattices

The experimental observation of light transport in large-scale temporal lattices that are parity–time symmetric is reported and it is demonstrated that periodic structures respecting this symmetry can act as unidirectional invisible media when operated near their exceptional points.

Entanglement transformation at absorbing and amplifying four-port devices

Abstract Quantum communication schemes widely use dielec-tric four-port devices as basic elements for construct-ing optical quantum channels. Since for causalityrea-sons the permittivity is

Parity–time-symmetric whispering-gallery microcavities

Optical systems combining balanced loss and gain provide a unique platform to implement classical analogues of quantum systems described by non-Hermitian parity–time (PT)-symmetric Hamiltonians. Such

Quantum-state transformation by dispersive and absorbing four-port devices

The recently derived input-output relations for the radiation field at a dispersive and absorbing four-port device [T. Gruner and D.-G. Welsch, Phys. Rev. A 54, 1661 (1996)] are used to derive the

Observation of parity–time symmetry in optics

One of the fundamental axioms of quantum mechanics is associated with the Hermiticity of physical observables 1 . In the case of the Hamiltonian operator, this requirement not only implies real