Due to complexity of the systems and processes it addresses, the development of computational quantum physics is influenced by the progress in computing technology. Here we overview the evolution, from the late 1980s to the current year 2020, of the algorithms used to simulate dynamics of quantum systems. We put the emphasis on implementation aspects and computational resource scaling with the model size and propagation time. Our mini-review is based on a literature survey and our experience in implementing different types of algorithms.
Some forms of classical simulations of quantum type probabilities and correlations are capable of violating Boole's conditions of possible experience, such as the Clauser-Horne-Shimony-Holt inequality, even beyond the Tsirelson bound. This can be achieved by communicating a single bit encoding the measurement context.
The numerical simulation of quantum circuits is an indispensable tool for development, verification and validation of hybrid quantum-classical algorithms on near-term quantum co-processors. The emergence of exascale high-performance computing (HPC) platforms presents new opportunities for pushing the boundaries of quantum circuit simulation. We present a modernized version of the Tensor Network Quantum Virtual Machine (TNQVM) which serves as a quantum circuit simulation backend in the eXtreme-scale ACCelerator (XACC) framework. The new version is based on the general purpose, scalable tensor n…
We introduce a hierarchy of semidefinite relaxations of the set of quantum correlations in generalised contextuality scenarios. This constitutes a simple and versatile tool for bounding the magnitude of quantum contextuality. To illustrate its utility, we use it to determine the maximal quantum violation of several noncontextuality inequalities whose maximum violations were previously unknown. We then go further and use it to prove that certain preparation-contextual correlations cannot be explained with pure states, thereby showing that mixed states are an indispensable resource for contextua…
Three ways to share a QPU: Scheduling strategies for hybrid Quantum-HPC applications
Politecnico di Torino（都灵理工大学）；LINKS Foundation（LINKS基金会）；E4 Computer Engineering SpA（E4计算机工程股份有限公司）；Barcelona Supercomputing Center (BSC)（巴塞罗那超级计算中心）；Università di Torino（都灵大学）；CINECA；Università di Bologna（博洛尼亚大学）；Dipartimento di Fisica e Astronomia ”G. Galilei”, Università di Padova（帕多瓦大学伽利略物理与天文系）；Istituto Nazionale di Fisica Nucleare (INFN)（意大利国家核物理研究所）
HPC-Driven Modeling with ML-Based Surrogates for Magnon-Photon Dynamics in Hybrid Quantum Systems
Simon Fraser University（西蒙弗雷泽大学）；Lawrence Berkeley National Laboratory（伯克利劳伦斯国家实验室）；Konan University（konan大学）；University of Wisconsin-Madison（威斯康星大学麦迪逊分校）；International Computer Science Institute（国际计算机科学研究所）；University of California, Berkeley（加州大学伯克利分校）
Simulating quantum contextuality with classical systems requires memory. A fundamental yet open question is what is the minimum memory needed and, therefore, the precise sense in which quantum systems outperform classical ones. Here, we make rigorous the notion of classically simulating quantum state-independent contextuality (QSIC) in the case of a single quantum system submitted to an infinite sequence of measurements randomly chosen from a finite QSIC set. We obtain the minimum memory needed to simulate arbitrary QSIC sets via classical systems under the assumption that the simulation shoul…
Sequences of compatible quantum measurements can be contextual and any simulation with a classical model accounting for the quantum observations, needs to use some internal memory. In Ref. [New J. Phys. 13, 113011 (2011)], it was shown that simulating the sequences of compatible observables from the Peres-Mermin scenario requires at least three different memory states in order to be not in contradiction with the deterministic predictions of quantum theory. We extend this analysis to the probabilistic quantum predictions and ask how much memory is required to simulate the quantum correlations g…
Open systems dynamics: Simulating master equations in the computer
主方程可能是任何研究耗散量子光学的人最基本的方程。在这种情况下，在计算机中编码和模拟这些方程的有效方法是非常有用的，在这篇笔记中，我试图以一种全面的方式介绍我是如何做到这一点的，重点是Matlab，但使其足够通用，以便可以直接翻译为任何其他语言或软件的选择。我的大部分方法都是从胡安·何塞·加西亚-里波尔（Juan José García-Ripoll）那里继承来的（他的数学能力我怎么称赞都不为过），我在这里和那里改变它们，以适应我（相当有限的）数字大脑的工作方式，并尽可能地将它们与我如何理解它们背后的理论联系起来。目前，笔记集中在如何编码主方程并找到它们的稳态，但我希望很快我就能用时间演化方法更新它们，包括如何处理依赖于时间的主方程。在过去的4年里，我在各种不同的背景下测试了这些方法，包括电路量子电动力学，激光问题，光学参量振荡器和光机系统。评论和（建设性的）批评是非常欢迎的，并将适当的信贷和承认。
We introduce a tensor network based emulator, simulating a programmable analog quantum processing unit (QPU). The software package is fully integrated in a cloud platform providing a common interface for executing jobs on a HPC cluster as well as dispatching them to a QPU device. We also present typical emulation use cases in the context of Neutral Atom Quantum Processors, such as evaluating the quality of a state preparation pulse sequence, and solving Maximum Independent Set problems by applying a parallel sweep over a set of input pulse parameter values, for systems composed of a large numb…
This article explores how probabilistic programming can be used to simulate quantum correlations in an EPR experimental setting. Probabilistic programs are based on standard probability which cannot produce quantum correlations. In order to address this limitation, a hypergraph formalism was programmed which both expresses the measurement contexts of the EPR experimental design as well as associated constraints. Four contemporary open source probabilistic programming frameworks were used to simulate an EPR experiment in order to shed light on their relative effectiveness from both qualitative …
First-principles calculations of high-temperature spin dynamics in solids in the context of nuclear magnetic resonance (NMR) is a long-standing problem, whose conclusive solution can significantly advance the applications of NMR as a diagnostic tool for material properties. In this work, we propose a new hybrid quantum-classical method for computing NMR free induction decay(FID) for spin $1/2$ lattices. The method is based on the simulations of a finite cluster of spins $1/2$ coupled to an environment of interacting classical spins via a correlation-preserving scheme. Such simulations are show…
Progress in quantum computing hardware raises questions about how these devices can be controlled, programmed, and integrated with existing computational workflows. We briefly describe several prominent quantum computational models, their associated quantum processing units (QPUs), and the adoption of these devices as accelerators within high-performance computing systems. Emphasizing the interface to the QPU, we analyze instruction set architectures based on reduced and complex instruction sets, i.e., RISC and CISC architectures. We clarify the role of conventional constraints on memory addre…
Ferrara University（费拉拉大学）；Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Ferrara（意大利国家核物理研究所（INFN）费拉拉分部）；CERN, Europen Organization for Nuclear Research（欧洲核子研究组织（CERN））；Dipartimento di Fisica, Università degli Studi di Milano（米兰大学物理系）；TIF Lab（TIF实验室）
This paper presents a novel quantum walk approach to simulating parton showers on a quantum computer. We demonstrate that the quantum walk paradigm offers a natural and more efficient approach to simulating parton showers on quantum devices, with the emission probabilities implemented as the coin flip for the walker, and the particle emissions to either gluons or quark pairs corresponding to the movement of the walker in two dimensions. A quantum algorithm is proposed for a simplified, toy model of a 31-step, collinear parton shower, hence significantly increasing the number of steps of the pa…
Response functions are a fundamental aspect of physics; they represent the link between experimental observations and the underlying quantum many-body state. However, this link is often under-appreciated, as the Lehmann formalism for obtaining response functions in linear response has no direct link to experiment. Within the context of quantum computing, and by using a linear response framework, we restore this link by making the experiment an inextricable part of the quantum simulation. This method can be frequency- and momentum-selective, avoids limitations on operators that can be directly …
