A Shanghai Jiao Tong University research team has announced the world’s first software for photonic analog quantum computing and simulation. “Feynman Photonic Analog Quantum Simulation” (FeynmanPAQS) is named after renown quantum physicist Richard P. Feynman.

FeynmanPAQS is designed to support a wide range of photonic analog quantum computing applications, such as single and multi-photon Quantum Walks (QW) and Boson sampling. It can also implement these theoretical experiments on a real quantum physical system, such as photonic chips. The research team was led by Prof. Xianmin Jin, who has been working on advanced quantum integration techniques since 2010. Dr. Jin told Synced that “once we have learned how to control the quantum physics system well, we can explore new physics and create much more powerful computational capabilities beyond today’s classic computers on specific problems.”

The software contains four major modules: Two-dimensional Quantum Walks (QW), Quantum Stochastic Walks on the photonic chip (QSW), Multi-Particle Quantum Walks (MultiParticle), and Boson Sampling.

Module for two-dimensional quantum walks with arbitrary Hamiltonian design (QW)

Quantum walks is the quantum equivalent of the classical random walks process, but with superpositions. The process shows superior performance over its classical computing counterparts in quantum searching and quantum simulation applications. To apply quantum walks to a wide range of applications, researchers need a two-dimensional evolution space of a large scale, and flexible design of the Hamiltonian for quantum walks.

This May, the same SJTU research team developed the world’s largest-scaled 3D photonic quantum chip that could demonstrate a 2D quantum walk. This time, they turned to Hamiltonian design, the lynchpin of quantum simulation. As the paper explains, “quantum simulation is to use the Hamiltonian of a quantum system to simulate the Hamiltonian of the target system.”

Researchers used the QW module to realize the continuous-time quantum walk of one single photonic quantum. The module for theoretically calculating quantum walks on a photonic system mainly includes the following four steps: Generate Hamiltonian, Evolve (Exponentiate Hamiltonian), Obtain Probability Distribution, and Apply Gaussian Facula.

Quantum stochastic walks on the photonic chip (QSW)

Quantum stochastic walks has proven to be useful for quantum simulation in a real-world environment. The QSW module, which references to a similar graphic-user-inference (GUI) of the QW module, requires users to define ∆β varies along the waveguide (by filling ‘z interval’), indicate which of the waveguides need to add ∆β variation (by choosing ‘Stochastic or not’), and input the number of random settings required to get an average result (by filling ‘Average of X times’), etc. The export data file function is also available in this module.

Multi-particle quantum walks (MultiParticle)

In the MultiParticle module, the system will allow the user to inject two or more indistinguishable particles instead of only one particle into the QW and QSW modules. This module focuses on quantum interference and quantum correlation simulation and calculation. The module is similar to the setting feature in QW and QSW modules, but the results can be exported in both graph and data forms.

Boson sampling

Boson sampling scheme is a simplified quantum computing model that only requires passive linear optics interferometer, a single photon source, and photodetection. This module will require users to input the matrix data set to set random parameters for injected photons. Both Reck’s type and Clements’s type decomposition are available in this module.

FeynmanPAQS also includes an installable MATLAB package and a simple Graphical User Interface (GUI) that enables operation even by users with little or no programming skill or experience. It is compatible with various integrated photonic quantum circuits, including Silicon-on-Insulator, Silica-on-Silicon, UV writing and femtosecond laser writing.

The FeynmanPAQS 1.0 software launched in an installable MATLAB package with user-friendly GUI. It will also be shared on cloud servers.

The paper FeynmanPAQS: A Graphical Interface Program for Photonic Analog Quantum Computing is on arXiv.