Superposition and entanglement are properties of the quantum nature that suggest the construction, programming and functioning of quantum computers. Specifically, they have been imagined as a means for solving the Schrodinger equation and calculating the energy of a quantum system, i. e. doing quantum chemistry on quantum computers. It has been shown recently that this is possible in principle. We present the basic ideas of the quantum algorithm for the solution of Schrodinger´s equation and the estimation of the resources needed for a quantum computer to achieve this task.
Superposition and entanglement are properties of the quantum nature that suggest the construction, programming and functioning of quantum computers. Specifically, they have been imagined as a means for solving the Schrodinger equation and calculating the energy of a quantum system, i. e. doing quantum chemistry on quantum computers. It has been shown recently that this is possible in principle. We present the basic ideas of the quantum algorithm for the solution of Schrodinger´s equation and the estimation of the resources needed for a quantum computer to achieve this task.
As we begin to reach the limits of classical computing, quantum computing has emerged as a technology that has captured the imagination of the scientific world. While for many years, the ability to execute quantum algorithms was only a theoretical possibility, recent advances in hardware mean that quantum computing devices now exist that can carry out quantum computation on a limited scale. Thus, it is now a real possibility, and of central importance at this time, to assess the potential impact of quantum computers on real problems of interest. One of the earliest and most compelling applications for quantum computers is Feynman's idea of simulating quantum systems with many degrees of freedom. Such systems are found across chemistry, physics, and materials science. The particular way in which quantum computing extends classical computing means that one cannot expect arbitrary simulations to be sped up by a quantum computer, thus one must carefully identify areas where quantum advantage may be achieved. In this review, we briefly describe central problems in chemistry and materials science, in areas of electronic structure, quantum statistical mechanics, and quantum dynamics that are of potential interest for solution on a quantum computer. We then take a detailed snapshot of current progress in quantum algorithms for ground-state, dynamics, and thermal-state simulation and analyze their strengths and weaknesses for future developments.
In principle, it is possible to model any physical system exactly using quantum mechanics; in practice, it quickly becomes infeasible. Recognising this, Richard Feynman suggested that quantum systems be used to model quantum problems [1]. For example, the fundamental problem faced in quantum chemistry is the calculation of molecular properties, which are of practical importance in fields ranging from materials science to biochemistry. Within chemical precision, the total energy of a molecule as well as most other properties, can be calculated by solving the Schrödinger equation. However, the computational resources required to obtain exact solutions on a conventional computer generally increase exponentially with the number of atoms involved [1, 2]. In the late 1990’s an efficient algorithm was proposed to enable a quantum processor to calculate molecular energies using resources that increase only polynomially in the molecular size [2–4]. Despite the many different physical architectures that have been explored experimentally since that time—including ions, atoms, superconducting circuits, and photons—this appealing algorithm has not been demonstrated to date.
As the year-to-year gains in speeds of classical computers continue to taper off, computational chemists are increasingly examining quantum computing as a possible route to achieve greater computational performance. Quantum computers, built upon the properties of superposition, interference, and entanglement of quantum bits, offer, in principle, the possibility to outperform classical computers for solving many important classes of problems. In the field of chemistry, quantum algorithm development offers promising propositions for solving classically intractable problems in areas such as electronic structure, chemical quantum dynamics, spectroscopy, and cheminformatics. However, physical implementations of quantum computers are still in their infancy and have yet to outperform classical computers for useful computations. Still, quantum software development for chemistry is a highly active area of research. In this perspective, we summarize recent progress in the areas of quantum computing algorithms, hardware, and software, and we describe the challenges that remain for useful implementations of quantum computing for chemical applications.
Quantum chemistry is concerned with solving the Schrodinger equation for chemically relevant systems. This is typically done by making useful and systematic approximations which form the basis for model chemistries. A primary contribution of this dissertation, is taking concrete steps toward establishing a new model chemistry based on quantum computation. Electronic energies of the system can be efficiently obtained to fixed accuracy using quantum algorithms exploiting the ability of quantum computers to efficiently simulate the time evolution of quantum systems. The quantum circuits for simulation of arbitrary electronic Hamiltonians are given using quantum bits associated with single particle basis functions. This model chemistry is applied to hydrogen molecule as a case study where all necessary quantum circuits are clearly laid out. Furthermore, our collaboration to experimentally realize a simplified version of the hydrogen molecule quantum circuit is also included in this thesis. Finally, alternatives to the gate model of quantum computation are pursued by exploring models based on the quantum adiabatic theorem and on the generalization of random walks.
Computational chemistry plays a vital role in material sciences. A fast evolving technology called quantum computing has shifted computational capabilities as it promises to solve impossible calculations in some areas of material sciences and drug development. In principle, quantum computers can solve certain problems in chemistry exponentially more quickly than classical computers. As quantum computers have an error-corrected quantum system, it reduces the quantum resources to run the quantum calculations in space drastically using the Trotterization approach with small qubitization. This nascent field is showing fast progress and potential benefits as it can process large amounts of information. The algorithms used for optimization and quantum simulations help to improve the advanced computational calculations for large clusters. These algorithms help in protein structure prediction to network analysis. Yet this nascent field has its own caveats and challenges. In this chapter, we introduce the basic architecture of quantum computing and its promises and limitations in the field of computational chemistry. The quantum algorithms revolutionizing quantum computing are discussed in detail.
Quantum computing is a novel kind of computation that solves very complicated problems rapidly by applying concepts from basic physics. Concepts like quantum mechanical computing and quantum algorithms are included in the field of quantum computing study. Researchers have imagined quantum computing as a revolutionary idea among emerging technologies in terms of concepts, methods, and techniques. These are cross-pollinated. Hence, quantum computing becomes more and more multidisciplinary. Quantum computing leverages quantum mechanical phenomena like superposition and quantum interference to deal with some kinds of problems more precisely than conventional computing. Because of its unique characteristics, which set it apart from conventional computers in terms of functionality and operation, quantum computing has grown in popularity. There are possibilities of creating hybrid models, namely approaches for large-scale mixed-integer programming issues, that effectively combine the strengths of quality control techniques with deterministic algorithms to handle combinatorial challenges.