Quantum correlations in PT-symmetric photonic integrated circuits

Información del proyecto

QUAPT

Identificador del acuerdo de subvención: 895254

DOI

10.3030/895254

Proyecto cerrado

Fecha de la firma de la CE 15 Abril 2020

Fecha de inicio 1 Diciembre 2020

Fecha de finalización 30 Abril 2023

Financiado con arreglo a

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Coste total

€ 162 806,40

Aportación de la UE

€ 162 806,40

Coordinado por

UNIVERSITAET ROSTOCK
Germany

Periodic Reporting for period 1 - QUAPT (Quantum correlations in PT-symmetric photonic integrated circuits)

Período documentado: 2020-12-01 hasta 2022-11-30

Resumen del contexto y de los objetivos generales del proyecto

A central principle in quantum mechanics is that all operators that are associated with observables have to be Hermitian, to ensure real eigenvalues. Surprisingly, it turned out that there exists a class of Hamiltonians which are non-Hermitian yet still possess real eigenvalues. These describe PT-symmetric materials, which are systems that are invariant under the combined operations of parity inversion and time reversal. Moreover, through tuning of a physical parameter, it is possible to induce a phase transition in which the PT symmetry breaks at an exceptional point, rendering the eigenvalue spectrum of the system complex. What implications PT symmetry has for quantum physics is still under debate. Yet, mapped onto a photonic platform, various unusual effects onto the evolution of light have already been demonstrated and the concept even found its way to applications in lasers, optical diodes and sensing. While these experiments have been inspired by quantum mechanical concepts, they have been purely classical so far. Quantum evolution of light in PT-symmetric systems is still completely unexplored territory, with lots of new physics to be unravelled. Therefore, the objective of this action was to experimentally investigate the evolution of quantum states in PT-symmetric systems. This was carried out by implementing quantum walks of multiple correlated photons injected in PT-symmetric photonic integrated circuits fabricated using femtosecond-laser direct writing technology.

Trabajo realizado desde el comienzo del proyecto hasta el final del período abarcado por el informe y los principales resultados hasta la fecha

The action investigated various aspects of the evolution of quantum states in PT-symmetric photonic systems. Two highlights are:
1) The nature of two-photon correlations in PT-symmetric quantum systems alternates between bunching and antibunching as a function of the evolution length. Furthermore, a symmetry has been identified that preserves the two-photon behaviour in sequences of non-Hermitian two-mode systems. These results have been submitted for publication and have been presented at several conferences.
2) Harnessing concepts from supersymmetry, one-dimensional photonic systems can be transformed into two-dimensional counterparts while preserving key properties of the system.
This facilitates the fabrication of photonic circuits for applications in perfect imaging and coherent transfer of quantum states. These findings have resulted in a publication and have been presented at several conferences.

Avances que van más allá del estado de la técnica e impacto potencial esperado (incluida la repercusión socioeconómica y las implicaciones sociales más amplias del proyecto hasta la fecha)

The action furthered the state of art by addressing the question what consequences the existence of PT-symmetric systems has for quantum physics, which put it at the forefront of fundamental research. Furthermore, the results demonstrate that non-Hermiticity in fact enables new functionality, which may impact the design of photonic integrated circuits for applications in advanced quantum information processing and sensing.

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