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Quantum correlations in PT-symmetric photonic integrated circuits

Project description

Photonics experiments could shed light on photon correlations and 'bunching' behaviours

In the early 1900s, the theories of Bohr, Planck and Einstein led to the first quantum model of the atom. All three went on to win Nobel Prizes for their work, establishing the basis of quantum theory. Hamiltonian mechanics, first formulated in the early 1800s for classical systems, and 'Hamiltonians' are now known to describe all physical systems, whether classical or quantum. However, until two decades ago, it was thought that so-called 'Hermitian Hamiltonians' apply to both classical and quantum systems and 'non-Hermitian Hamiltonians' apply only to classical mechanics. The discovery that the latter was not true opened an important new area of study, particularly from an experimental standpoint. The EU-funded QUAPT project is exploiting photonics to investigate experimentally, for the first time, the evolution of quantum states in non-Hermitian systems with expected pioneering insights into photon correlations and new physics.

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.

Fields of science (EuroSciVoc)

Keywords

Programme(s)

Topic(s)

Funding Scheme

MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)

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Call for proposal

(opens in new window) H2020-MSCA-IF-2019

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Coordinator

UNIVERSITAT ROSTOCK
Net EU contribution
€ 162 806,40
Address
UNIVERSITATSPLATZ 1
18055 Rostock
Germany
Region
Mecklenburg-Vorpommern Mecklenburg-Vorpommern Rostock, Kreisfreie Stadt
Activity type
Higher or Secondary Education Establishments
Links
Total cost
€ 162 806,40