Quantum transport simulations in a programmable nanophotonic processor

Abstract: Environmental noise and disorder play critical roles in quantum particle and wave transport in complex media, including solid-state and biological systems. Recent work has predicted that coupling between noisy environments and disordered systems, in which coherent transport has been arrested due to localization effects, could actually enhance transport. Photonic integrated circuits are promising platforms for studying such effects, with a central goal being the development of large systems providing low-loss, high-fidelity control over all parameters of the transport problem. Here, we fully map the role of disorder in quantum transport using a nanophotonic processor consisting of a mesh of 88 generalized beamsplitters programmable on microsecond timescales. Over 64,400 transport experiments, we observe several distinct transport regimes, including environment-assisted quantum transport and the ''quantum Goldilocks'' regime in strong, statically disordered discrete-time systems. Low loss and high-fidelity programmable transformations make this nanophotonic processor a promising platform for many-boson quantum simulation experiments.

• The paper demonstrates environment-assisted quantum transport by conducting over 64,000 experiments on a programmable nanophotonic processor.
• The paper utilizes a silicon photonic integrated circuit with 176 phase modulators and 88 Mach-Zehnder interferometers to control static and dynamic disorder.
• The paper reveals that optimal environmental noise, observed in the quantum Goldilocks regime, significantly enhances transport efficiency and offers new insights for quantum technologies.

Quantum Transport Simulations in a Programmable Nanophotonic Processor

This paper presents research on quantum transport phenomena using a programmable nanophotonic processor (PNP) capable of simulating complex quantum systems. The study focuses on the interactions between quantum transport and environmental noise in disordered systems, exploring the field of environment-assisted quantum transport (ENAQT) within a discrete-time framework. The investigated platform, a silicon-based photonic integrated circuit, features advanced programmability with 176 phase modulators and 88 Mach-Zehnder interferometers, enabling detailed simulations of quantum walks (QWs).

Quantum Transport and Disorder

Within the study, QWs serve as the core computational paradigm, examined for their capacity to model quantum transport (QT). The programmable nanophotonic processor allows the simulation of various QT scenarios, including those involving static and dynamic disorder. Static disorder is introduced by a time-invariant random variation, while dynamic disorder is induced by time-varying randomness. The paper conducts an extensive exploration of over 64,000 transport experiments, revealing distinct QT regimes, including Anderson localization and ENAQT, achieved by modulating the disorder parameters in the nanophotonic processor.

Experimental Platform and Methodology

The PNP leverages high-density silicon photonics for this exploratory study, showcasing reduced losses and enhanced fidelity in configuring quantum transport simulations. The circuit’s configuration is effectuated through adjustable beamsplitters that incorporate thermo-optic phase shifters. With precise control over the quantum system's disorder space, the platform measures and evaluates quantum transport behaviors over a comprehensive range of parameter combinations, ensuring the observation's statistical robustness.

Key Findings

The results corroborate the presence of ENAQT, a phenomenon where environmental dynamics assist in counteracting localization due to static disorder, facilitating transport in quantum systems. This effect is observed across simulations that incorporated varying degrees of static and dynamic disorder, particularly elucidating the "quantum Goldilocks" regime, where optimal environmental noise significantly enhances transport efficiency. The realizations within this discrete-time framework extend the conceptual understanding of ENAQT beyond previously explored continuous-time systems.

Implications and Future Direction

The research underscores the potential of programmable nanophotonic processors as versatile platforms for simulating and understanding QT phenomena. Practically, the ability to probe dynamic and static disorder simultaneously allows researchers to disentangle complex transport dynamics, offering insights into both fundamental quantum mechanics and potential applications such as photonic quantum computing.

The study's scope proposes several future research trajectories, including extending the investigation to multi-photon and higher-dimensional systems, which would push deeper into the quantum-classical boundary. Furthermore, refining device fabrication could alleviate current setup losses, thus enhancing the scalability of such experiments. The integration of chip-based quantum resources, like single-photon sources and detectors alongside emerging feed-forward mechanisms, further unmask the potential of PNPs in advanced quantum simulation and information processing applications.

In essence, this paper offers a detailed investigation into quantum transport dynamics facilitated by a cutting-edge quantum photonic platform, presenting rich avenues for future exploration within quantum mechanics and quantum technologies.