Fock space exploration by angle resolved transmission through quantum diffraction grating of cold atoms in an optical lattice

Light transmission or diffraction from different quantum phases of cold atoms in an optical lattice has recently come up as a useful tool to probe such ultra cold atomic systems. The periodic nature of the optical lattice potential closely resembles the structure of a diffraction grating in real space, but loaded with a strongly correlated quantum many body state which interacts with the incident electromagnetic wave, a feature that controls the nature of the light transmission or dispersion through such quantum medium. In this paper we show that as one varies the relative angle between the cavity mode and the optical lattice, the peak of the transmission spectrum through such cavity also changes reflecting the statistical distribution of the atoms in the illuminated sites. Consequently the angle resolved transmission spectrum of such quantum diffraction grating can provide a plethora of information about the Fock space structure of the many body quantum state of ultra cold atoms in such an optical cavity that can be explored in current state of the art experiments.Comment: 40 double spaced, single column pages, 40 .eps figures, accepted for publication in Physical Review

8x8 Reconfigurable quantum photonic processor based on silicon nitride waveguides

The development of large-scale optical quantum information processing circuits ground on the stability and reconfigurability enabled by integrated photonics. We demonstrate a reconfigurable 8x8 integrated linear optical network based on silicon nitride waveguides for quantum information processing. Our processor implements a novel optical architecture enabling any arbitrary linear transformation and constitutes the largest programmable circuit reported so far on this platform. We validate a variety of photonic quantum information processing primitives, in the form of Hong-Ou-Mandel interference, bosonic coalescence/anticoalescence and high-dimensional single-photon quantum gates. We achieve fidelities that clearly demonstrate the promising future for large-scale photonic quantum information processing using low-loss silicon nitride.Comment: Added supplementary materials, extended introduction, new figures, results unchange

Quantum photo-thermodynamics on a programmable photonic quantum processor

One of the core questions of quantum physics is how to reconcile the unitary evolution of quantum states, which is information-preserving and time-reversible, with the second law of thermodynamics, which is neither. The resolution to this paradox is to recognize that global unitary evolution of a multi-partite quantum state causes the state of local subsystems to evolve towards maximum-entropy states. In this work, we experimentally demonstrate this effect in linear quantum optics by simultaneously showing the convergence of local quantum states to a generalized Gibbs ensemble constituting a maximum-entropy state under precisely controlled conditions, while using a new, efficient certification method to demonstrate that the state retains global purity. Our quantum states are manipulated by a programmable integrated photonic quantum processor, which simulates arbitrary non-interacting Hamiltonians, demonstrating the universality of this phenomenon. Our results show the potential of photonic devices for quantum simulations involving non-Gaussian states

8×8 Programmable Quantum Photonic Processor based on Silicon Nitride Waveguides

Integrated universal linear optical networks are essential for the development of quantum information processing (QIP). We demonstrate a universal, reconfigurable, 8×8 photonic processor based on Si3N4 waveguides showing a variety of QIP primitives

8×8 programmable Si3N4 photonic processor for linear quantum processing

Universal linear optical networks made of on-chip tunable beam splitters and phase shifters form a very promising platform for quantum information processing (QIP). Thanks to their phase stability and reconfigurability, they are robust and enable a variety of quantum information and communication protocols such as quantum teleportation [1], quantum key distribution [2], photonic qubit gate protocols [3] and boson sampling [4]. Two known materials for on-chip platforms are silicon-on-insulator (SOI) and doped silica, where SOI allows for a high component density due to its high index contrast and silica has a low loss