PhotoniQLAB: a framework for simulating photonic quantum information processing experiments

Abstract

Simulators for photonic quantum information processing (PQIP) experiments are essentially different with currently available quantum-circuit simulators. In PQIP experiments, photons are usually encoded by multiple degrees of freedom, some of which are multi-level or even infinite-level. Moreover, the evolution of indistinguishable photons cannot be described elegantly by the model used in quantum-circuit simulators. A simulator focusing on PQIP experiments is urgently needed, as it plays an important role in PQIP experiments designing and verification. We developed PhotoniQLAB, an object-oriented framework designed for simulating PQIP experiments, which provides a virtual-lab user experience. The core simulation unit is a computer algebraic system based on the second quantization method. PhotoniQLAB only requires users to enter the structure information of a target PQIP experiment to conduct a simulation, as it can understand the topological structure by itself. The mathematical foundation and technical details of PhotoniQLAB are discussed in the paper. The performance of PhotoniQLAB, which is analyzed and used to simulate several experimental schemes in this paper, has been shown to be efficient enough for near-term PQIP experiments. PhotoniQLAB shows its flexibility and universality, through simulating more than 60 existing PQIP experiments in published papers. We believe that PhotoniQLAB will become a fundamental PQIP software infrastructure facilitating the analyses and designs of PQIP experiments.

An Overlap-Integral Approach to Quantum Optical Simulation

“…( 1) with appropriate identity operators, then the exponents can be extracted from the fact that the elements of the resulting column vector of the output state represent counting number states in a base N + 1 number system: |0000 is the first element, |0001 is the second element, and so on until we reach the final (N + 1) 4 element |N N N N . This is not the most truncated way of expressing these modes, but it is highly efficient [13].…”

“…It is important to note that an example HOM experiment is provided by Ref. [13]. However, this example is of an HOM-like experiment in the polarization degree of freedom of the photon, which is not the full multimode example in the temporal degree of freedom simulated by our technique in Section III-B.…”

“…This issue is partially addressed in Ref. [13]; however, it does not provide a specific way to incorporate an approximate continuum of spectrotemporal modes. It should be noted that this does not mean that the techniques of Refs.…”

“…It should be noted that this does not mean that the techniques of Refs. [6]- [13], or even Refs. [2]- [5] are without merrit.…”

“…Simulating quantum systems on classical hardware has been considered in previous works [2]- [13]. However, many of these simulation techniques either use well-known numerical techniques based on preexisting knowledge of an underlying quantum system [2]- [5], or are specifically designed for qubit/qudit systems [6]- [11] or for finitely many photonic modes [12], [13]. For the former, such simulations are typically stochastic, which is insufficient to agnostically simulate any possible quantum situation.…”