Reconfigurable optical implementation of quantum complex networks

Abstract

Network theory has played a dominant role in understanding the structure of complex systems and their dynamics. Recently, quantum complex networks, i.e.collections of quantum systems arranged in a non-regular topology, have been theoretically explored leading to significant progress in a multitude of diverse contexts including, e.g., quantum transport, open quantum systems, quantum communication, extreme violation of local realism, and quantum gravity theories. Despite important progress in several quantum platforms, the implementation of complex networks with arbitrary topology in quantum experiments is still a demanding task, especially if we require both a significant size of the network and the capability of generating arbitrary topology-from regular to any kind of non-trivial structure-in a single setup. Here we propose an all optical and reconfigurable implementation of quantum complex networks. The experimental proposal is based on optical frequency combs, parametric processes, pulse shaping and multimode measurements allowing the arbitrary control of the number of the nodes (optical modes) and topology of the links (interactions between the modes) within the network. Moreover, we also show how to simulate quantum dynamics within the network combined with the ability to address its individual nodes. To demonstrate the versatility of these features, we discuss the implementation of two recently proposed probing techniques for quantum complex networks and structured environments.

Unveiling noiseless clusters in complex quantum networks

“…We consider a model of interacting quantum harmonic oscillators (nodes) with linear interactions (links), so our system belongs to the second class of complex quantum networks as described above. Reconfigurable and controllable complex quantum networks can be experimentally realized with optical 30 as well as circuit QED 16 set-ups, paving the way to new investigations on the interplay between topology and dynamical properties.…”

“…Beyond topological features, we have considered inhomogeneous parameters for nodes and links as these can actually be unavoidable in experiments. 16,30 For the frequency combs platform, 30 this experimental analysis has not yet been reported but the possibility to achieve identical nodes is discussed in ref. 83 through chirping of the pump optical mode.…”

“…21,25,26 Can we use a local quantum probe to extract global information on a complex quantum network? [28][29][30] Can we use complex quantum networks as quantum simulators of nontrivial open quantum systems? 28,30,31 How do emergent phenomena known in classical complex networks arise into the quantum regime?…”

“…[28][29][30] Can we use complex quantum networks as quantum simulators of nontrivial open quantum systems? 28,30,31 How do emergent phenomena known in classical complex networks arise into the quantum regime? [32][33][34][35] Moving toward scalable multi-component architectures of increasing complexity, it is imperative to understand how resilient are complex quantum networks to the presence of external perturbations.…”

Non-Markovianity over Ensemble Averages in Quantum Complex Networks

“…Perhaps the most promising alternative is the very recently proposed optical implementation of the dynamics given by the Hamiltonian (2.1), based on a simultaneous downconversion of the components of an optical frequency comb from a femtosecond laser followed by pulse shaping and mode-selective measurements [38]. By mapping the Hamiltonian to quadrature operators of the optical field modes and determining the so-called Bloch-Messiah decomposition of either the symplectic matrix (2.5) or (2.6), one will find the pulse shape and measurement basis necessary to implement it.…”