arXiv subjects

Rohan Yadgirkar

Publications and source records attributed to Rohan Yadgirkar.

6 recordsLinked to original sources

arXiv2026

Programmable Non-Hermitian Synchronization of Light on a Silicon Photonic Processor

Synchronization is a pervasive collective phenomenon underlying the firing of neurons, the beating of the heart, and the coherent emission of lasers. Across these systems, dissipation plays an organizing role, suppressing microscopic differences and steering coupled units toward a common macroscopic order. Here we harness engineered non-Hermitian dissipation to synchronize light directly in the optical domain. Implementing non Hermitian transition matrices on a silicon photonic processor, we drive arbitrary multimode optical fields toward a unique collective state with equal modal intensities and a globally locked phase, a process we call dissipation-induced phase synchronization. The synchronization rate and total optical power throughput are independently programmable, enabling control over the dissipative dynamics without compromising reconfigurability. These results recast dissipation as a functional resource and open a route to reconfigurable on-chip synchronization for classical and quantum photonic technologies.

physics.optics↗

arXiv2026

Bloch Siegert Physics in a Reconfigurable Photonic Binary Lattice

The Bloch Siegert shift, a hallmark correction arising from counter-rotating interactions in driven two-level systems, has an exact counterpart in binary lattices under static forcing, where it governs resonant long-range tunneling between sites separated by odd lattice spacings. Here we report the first experimental realization of this correspondence using a 12 mode programmable photonic integrated circuit. By implementing a reconfigurable binary lattice with sub-percent control of on-site detuning, we observe coherent periodic jumps across four resonance orders and quantitatively verify the predicted period law over the full parameter space. The measured dynamics exhibit the extreme resonance sensitivity characteristic of Bloch Siegert physics and agree closely with the level-anticrossing picture of the semiclassical Rabi model. Exploiting the underlying parity structure, we further convert intrinsically bidirectional oscillations into cascaded unidirectional transport through adaptive sign reversal of the staggered potential, achieving fidelities exceeding 0.95 and 0.98 on the same hardware platform. Our results establish programmable photonic lattices as a scalable testbed for strongly driven quantum-optical phenomena and Floquet-engineered transport.

quant-ph↗

arXiv2026

Experimental simulation of non-equilibrium quantum piston on a programmable photonic quantum computer

Quantum fluctuation relations provide a microscopic formulation of thermodynamics beyond equilibrium, but experimentally accessing many-body quantum work statistics remains an outstanding challenge. The quantum piston constitutes a canonical model of boundary-driven nonequilibrium dynamics, where finite-time deformation of a confining potential generates non-adiabatic transitions, dissipation and irreversibility. Here we experimentally simulate the nonequilibrium dynamics of a two-boson quantum piston on a programmable photonic quantum computer. Using two indistinguishable photons, we encode a truncated piston propagator through a quasi-unitary embedding, with an ancilla mode representing leakage into higher-energy states outside the resolved manifold. This architecture enables direct reconstruction of thermodynamic transition statistics for both expansion and compression protocols as functions of driving speed and final trap length. We observe the crossover from quasi-adiabatic to strongly non-adiabatic evolution and show that bosonic interference restructures the resulting two-particle Fock-state populations and work distributions. The measured statistics are in close agreement with theoretical predictions and satisfy the Jarzynski equality across expansion and compression protocols for cyclic driving we further quantify irreversibility through dissipated work and state overlap. Our work identifies programmable photonic quantum hardware as a powerful platform for simulating nonequilibrium quantum thermodynamics and for experimentally resolving how indistinguishability and many-body interference shape quantum work, dissipation and entropy production.

quant-ph↗

arXiv2025

Non-Hermitian Exceptional Topology on a Klein Bottle Photonic Circuit

Non-Hermitian physics has unlocked a wealth of unconventional wave phenomena beyond the reach of Hermitian systems, with exceptional points (EPs) driving enhanced sensitivity, nonreciprocal transport, and topological behavior unique to non-Hermitian degeneracies. Here, we present a scalable and reconfigurable silicon photonic integrated circuit capable of emulating arbitrary non-Hermitian time evolution with high precision. Using this programmable platform, we implement a two-band non-Hermitian Hamiltonian defined on a Klein-bottle topology a nonorientable parameter space that enables exceptional phases forbidden on orientable manifolds. Through an on-chip amplitude-and-phase reconstruction protocol, we retrieve the full complex Hamiltonian at multiple points in parameter space and experimentally map the associated Fermi arc where the imaginary eigenvalue gap closes. The orientation of the measured Fermi arc reveals a nontrivial exceptional topology: it implies the presence of same-charge EPs (or an EP monopole) that cannot annihilate locally on the Klein bottle. Our results demonstrate the first photonic realization of exceptional topology on a nonorientable manifold and establish a versatile platform for exploring exotic non-Hermitian and topological models relevant to classical and quantum photonics.

physics.optics↗

arXiv2025

Emulation of Coherent Absorption of Quantum Light in a Programmable Linear Photonic Circuit

Non-Hermitian quantum systems, governed by nonunitary evolution, offer powerful tools for manipulating quantum states through engineered loss. A prime example is coherent absorption, where quantum states undergo phase-dependent partial or complete absorption in a lossy medium. Here, we demonstrate a fully programmable implementation of nonunitary transformations that emulate coherent absorption of quantum light using a programmable integrated linear photonic circuit, with loss introduced via coupling to an ancilla mode [Phys. Rev. X 8, 021017; 2018]. Probing the circuit with a single-photon dual-rail state reveals phase-controlled coherent tunability between perfect transmission and perfect absorption. A two-photon NOON state input, by contrast, exhibits switching between deterministic single-photon and probabilistic two-photon absorption. Across a range of input phases and circuit configurations, we observe nonclassical effects such as anti-coalescence and bunching, along with continuous and coherent tuning of output Fock state probability amplitudes. Classical Fisher information analysis reveals phase sensitivity peaks of 1 for single-photon states and 3.4 for NOON states, the latter exceeding the shot-noise limit of 2 and approaching the Heisenberg limit of 4 for two-photon states. The experiment integrates quantum state generation, programmable photonic circuitry, and photon-number-resolving detection, establishing ancilla-assisted circuits as powerful tools for programmable quantum state engineering, filtering, multiplexed sensing, and nonunitary quantum simulation.

quant-ph↗

arXiv2025

Floquet-driven light transport in programmable photonic processors via discretized evolution of synthetic magnetic fields

Photons, unlike electrons, do not couple directly to magnetic fields, yet synthetic gauge fields can impart magnetic-like responses and enable directional transport. Discretized Floquet evolution provides a controlled route, where the time-ordered sequencing of non-commuting Hamiltonians imprints complex hopping phases and breaks time-reversal symmetry. However, stabilizing such driven dynamics and observing unambiguous signatures of these effects on a reconfigurable platform has remained challenging. Here we demonstrate synthetic gauge fields for light on a programmable photonic processor by implementing discretized Floquet drives that combine static and dynamic phases. The resulting dynamics exhibit chiral circulation that reverses under drive inversion, flux-controlled interference with high visibility, and robust directional flow stabilized by optimizing the driving period. We further characterize the system using a first-harmonic phase as an order parameter, whose per-period winding number quantifies angular drift and reverses sign with the drive order. These results establish discretized Floquet evolution as a versatile framework for driven photonics, providing a programmable route to engineer gauge fields, stabilize driven phases, and probe winding-number signatures of chiral transport.

physics.optics↗