QUAPT · Quantum correlations in PT-symmetric photonic integrated circuits
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2020-12-01 → 2023-04-30
- EU contribution
- €162,806
- Participants
- 1
- Scheme
- MSCA-IF
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Results in brief
Quantum correlations in PT-symmetric photonic integrated circuits
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.
Data: CORDIS, © European Union
Project objective
In 1998, one of the fundamental assumptions in quantum mechanics, that the Hamiltonian describing a quantum system has to be Hermitian, was overturned. The existence of an entire class of Hamiltonians that are non-Hermitian yet still possess real eigenvalues was discovered. These non-Hermitian Hamiltonians describe PT-symmetric systems, which are systems that are invariant under the combined operations of parity-inversion and time-reversal. Currently, it is still under debate what implications PT-symmetry has for quantum physics. Yet in photonics, PT-symmetry can be readily realized by a proper distribution of gain and loss in the system, making photonics the ideal platform for studying the physics of PT-symmetric systems.Indeed, various effects of PT-symmetry such as non-orthogonal eigenmodes, non-reciprocal evolution of light, and diffusive coherent transport have been demonstrated on a photonic platform, and inspired applications in lasers and optical diodes. So far, these photonic experiments have been purely classical and the full impact of PT-symmetry on the evolution of light is still unclear. Quantum evolution of light in PT-symmetric systems is completely unexplored territory with lots of new physics to be unravelled.Therefore, the objective of this proposal is to for the first time experimentally investigate the evolution of quantum states in non-Hermitian systems. In particular, the project will study the quantum evolution of multiple correlated photons injected in PT-symmetric integrated photonic structures fabricated using direct laser-writing technology. The aim is to investigate how modifying the non-Hermitian Hamiltonian of the system influences photon correlations, expecting to demonstrate novel behaviour and unravel new physics. It is expected to find that quantum correlations fundamentally change: for example, correlated photons that should naturally bunch might anti-bunch, show a mixed bunching-antibunching, or even uncorrelated behaviour.
Original text from CORDIS.
Participants
- UNIVERSITAET ROSTOCK · RostockCoordinatorGermany
Links
Data: CORDIS, © European Union