arXiv subjects

Neelan Gounden

Publications and source records attributed to Neelan Gounden.

4 recordsLinked to original sources

arXiv2026

Nonlocal wavefront shaping through complex media

Wavefront shaping is a key technique for mitigating scattering in complex media, enabling advanced imaging and optical communication. Yet existing approaches are inherently local, requiring active correction elements - such as spatial light modulators or deformable mirrors - to lie directly in the optical path of the scattered light, which limits their integration into compact imaging systems. Here, we experimentally demonstrate nonlocal wavefront shaping using spatially entangled photon pairs. By applying a phase correction to a photon that never interacts with the scattering medium, we compensate for the distortions experienced by its entangled partner and restore their initial spatial correlations. Our approach physically decouples the wavefront correction from the scattering medium, paving the way for imaging through complex media in compact and otherwise inaccessible systems.

quant-ph↗

arXiv2026

Towards reconstructing quantum structured light on a quantum computer

We introduce a variational quantum computing approach for quantum state reconstruction within a discretized logical framework, using experimental measurement data as input. By mapping the reconstruction cost function onto an Ising model, the problem can be solved using a variational eigensolver on present-day quantum hardware identifying dominant logical elements of the density matrix. As a proof of concept, we demonstrate the method on quantum structured light, in particular, entangled photons carrying orbital angular momentum and show that the reconstruction procedure can yield reliable performance even on noisy devices. Our results highlight the potential of variational algorithms as a complementary approach to quantum state tomography, particularly for high-dimensional structured light, where classical approaches can face bottlenecks.

quant-ph↗

arXiv2025

Unveiling the link between quantum ghost imaging and Grover's quantum searching algorithm

Photonic quantum technologies have become pivotal in the implementation of communication, imaging and computing modalities. Among these applications, quantum ghost imaging (GI) exploits photon correlations to surpass classical limits, with recent advances in spatial-mode encoding and phase imaging. In parallel, all-optical computing offers powerful, passive-light processing capabilities. Here, we explore the intersection of these domains, revealing a conceptual and operational link between GI and Grover's quantum search algorithm (GSA) which is designed to search for elements in an unstructured database. Here, the elements are encoded as phases in the position basis states of photons. To show this, we use entangled photon pairs, with one photon encoding the oracle features while the other photon is used to find the marked element.

quant-ph↗

arXiv2025

The topological spectrum of high dimensional quantum states

Topology has emerged as a fundamental property of many systems, manifesting in cosmology, condensed matter, high-energy physics and waves. Despite the rich textures, the topology has largely been limited to low dimensional systems that can be characterised by a single topological number, e.g., a Chern number in matter or a Skyrme number in waves. Here, using photonic quantum states as an example, we harness the synthetic dimensions of orbital angular momentum (OAM) to discover a rich tapestry of topological maps in high dimensional spaces. Moving beyond spin textured fields, we demonstrate topologies using only one degree of freedom, the OAM of light. By interpreting the density matrix as a non-Abelian Higgs potential, we are able to predict topologies that exist as high dimensional manifolds which remarkably can be deconstructed into a multitude of simpler maps from disks to disks and spheres to spheres, giving rise to the notion of a topological spectrum rather than a topological number. We confirm this experimentally using quantum wave functions with an underlying topology of 48 dimensions and a topological spectrum spanning over 17000 maps, an encoding alphabet with enormous potential. We show that the topological spectrum allows the simultaneous ability to be robust to and probe for perturbation, the latter made possible by observing emergent signatures in the non-topological (trivial) spaces of the spectrum. Our experimental approach benefits from easy implementation, while our theoretical framework is cast in a manner that can be extrapolated to any particle type, dimension and degree of freedom. Our work opens exciting future possibilities for quantum sensing and communication with topology.

quant-ph↗