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Multi-mode interferometers can be used for a wide range of applications. They allow a higher precision for a phase measurement compared to a simple two-mode version [1, 2]. In quantum optics, schemes for enhancement of non-classical visibility [3] as well as better resilience to photon loss [4] have been proposed. All these schemes depend on a good stability of the used interferometer, which gives...
We provide a brief introduction to supersymmetric photonics and present our newest theoretical findings and experimental results on SUSY mode conversion and the scattering dynamics of light propagating in optical SUSY partner structures. Finally, we show how these notions can be harnessed in a SUSY-inspired extension of transformation optics, enabling the substitution of high-refractive-index arrangements...
We experimentally demonstrate that disorder can induce a topologically non-trivial phase. We implement this “Topological Anderson Insulator” in arrays of evanescently coupled waveguides and demonstrate its unique features.
We demonstrate theoretically and experimentally the Rashba effect using light in two “counterpropagating” photonic lattices. We observe breaking of inversion symmetry in the resulting band structure.
We show how classical light can be used to simulate a nonclassical quantum process. Specially modulated optical waveguides were utilized to emulate two-mode squeezed vacuum states as the light amplitudes in our arrays correspond to the photon number distribution of the squeezed states. In our experiments demonstrate a transition from photon number growth to periodic Bloch oscillations for increased...
We experimentally realize the generation of high-order photon encoded W-states involving up to 16 optical modes. Furthermore, we exploit the inherent probabilistic properties of these multipartite entangled W-states for generating genuine random numbers.
Two photons in an entangled, spatially correlated (anti-correlated) state transmitted through an Anderson disordered lattice maintain their correlation (anti-correlation) but exhibit coincidence-map speckle in the Fourier plane.
Quantum computation with large numbers of qubits is often envisioned to be facilitated by the division of one large register into several smaller units. The efficient information processing then relies on a coherent transfer of qubits between these units. Chains of spin-1/2-particles possessing nearest-neighbor interactions have been proposed as a platform for perfect transfer [1]. In theory, promising...
Quantum random walks of identical particles are ubiquitous in various fields of physics [1]. They give rise to particle number correlations which have been explored in several discrete systems [2; 3]. However, an essential property of all these quantum systems is their Hermiticity. Recently parity-time(PT)-symmetric systems [4] attracted much attention. The Hamiltonians of such systems are not necessarily...
Entangled photon pairs, so-called biphotons, play a central role in the discussion of nonlocal quantum correlations. Moreover, they give rise to various applications such as quantum cryptography, teleportation and quantum computation. Particular versatile plattforms to investigate strong quantum correlations of entangled photons in a robust environment are optical waveguide arrays [1; 2]. However,...
It is a popular belief that in one-dimensional (1D) systems the presence of any amount of disorder would lead to localized eigenstates - the so-called Anderson localization [1]. In contrast, a few theoretical counter-examples show that an amount of correlations in a disordered potential can lead to long-range transport. The prototypical case is the Random Dimer Model (RDM) [2] where in the context...
The one-dimensional (1D) Dirac equation governs the dynamics of relativistic fermions. Several of its elusive predictions have been successfully investigated in classical optical simulators, for massive [1] as well as for massless [2] fermions.
The manipulation of the phase of classical and quantum light is a major key to quantum photonics [1]. Integrated optics has several advantages over bulk optical systems, most notably in robustness, handling and size. Writing three-dimensional waveguides circuits into transparent materials using an ultrafast laser is thereby a new emerging technology [2; 3] with possible applications in quantum communication...
A topological insulator is a completely new phase of matter with an insulating interior and conduction only at the edges [1]. Perhaps its most impressing feature is that the conducting electron states at the edges do not experience scattering in case of defects or disorder due to the Kramers degeneracy, which disallows coupling to the counterpopagating state. This provides a robustness which is otherwise...
Within the context of particle dynamics in low-dimensional systems, it is widely believed that the system's structure predetermines the transport regime, e.g. ballistic, diffusive, or localized. More specifically, it is assumed that the existence of randomness within the system is necessary in order to observe diffusive or even localized transport[1]. On the other hand, in the absence of randomness,...
The coherent transport of quantum states between distant qubits is one of the key milestones towards the realisation of large-scale quantum computers [1]. For static qubits, this state transfer is often envisioned to be carried out only by the internal dynamics of the system, which has the great advantage that detrimental influences of the environment are minimised. A chain of spin-1/2-qubits with...
Wave transport in time-independent potentials is formally divided into two major categories depending on how the second moment of the evolving excitation grows with “time”. If translational symmetry is present, the eigenmodes of the system are plane waves or Floquet-Bloch modes [1], and the variance of an initially localized excitation increases quadratically in time (ballistic spreading). On the...
We experimentally demonstrate the impact of disorder on edge states in photonic graphene and find strong evidence that not only chirality but also the vanishing of the density-of-states at zero-energy is preserved under structural disorder.
The evolution of spatially extended, entangled, anti-correlated two photon states in photonic waveguide arrays that induce classical transverse Anderson localization is theoretically and experimentally investigated.
We present the first experimental observation of a Floquet Topological Insulator in any physical system. We realize optical topologically-protected unidirectional edge states, without magnetic fields, using honeycomb photonic lattice of helical waveguides.
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