Quantum Simulation with a Quantum Computer

Yuranan Kitrungrotsakul, Prabhas Chongstitvatana

Although a quantum computer is the future of computing, its practical implementation is still far off. Programming a quantum computer is also difficult. Thus, using a quantum computer simulator is a way to learn how to use a quantum computer. QCL is one of the quantum computer simulators. It can simulate the quantum environment and execute quantum computer programs. However, the quantum computer simulator has limited storage due to its data structure that simulates quantum bits. It takes long time to simulate a large number of quantum bits. This work proposes an accelerator of quantum simulator which is implemented in hardware circuits with Field Programmable Gate Array technology.

Rüdiger Schack

Fan Heng

In past few years, quantum computation and quantum simulation have been developed rapidly. The research on quantum computation and quantum simulation involving medium scale number of qubits will have a development priority. In this paper, we review recent developments in those directions. The review will include quantum simulation of many-body system, quantum computation, digital quantum simulators and cloud quantum computation platforms, and quantum software. The quantum simulation of many-body system will include the simulation of quantum dynamics, time crystal and many-body localization, quantum statistical physics and quantum chemistry. The review of those results is based on our consideration to the current characteristics of quantum computation and quantum simulation. Specifically, the number of available qubits is on a medium scale from dozens to several hundreds, the fidelity of the quantum logic gate is not high enough for several thousand of operations. In this sense, the present research is at the stage from fundamental explorations to practical applications. With these in mind, we hope that this review can be helpful for the future study in quantum computation and quantum simulation.

Viv M. Kendon, Kae Nemoto, William J. Munro

We briefly review what a quantum computer is, what it promises to do for us and why it is so hard to build one. Among the first applications anticipated to bear fruit is the quantum simulation of quantum systems. While most quantum computation is an extension of classical digital computation, quantum simulation differs fundamentally in how the data are encoded in the quantum computer. To perform a quantum simulation, the Hilbert space of the system to be simulated is mapped directly onto the Hilbert space of the (logical) qubits in the quantum computer. This type of direct correspondence is how data are encoded in a classical analogue computer. There is no binary encoding, and increasing precision becomes exponentially costly: an extra bit of precision doubles the size of the computer. This has important consequences for both the precision and errorcorrection requirements of quantum simulation, and significant open questions remain about its practicality. It also means that the quantum version of analogue computers, continuous-variable quantum computers, becomes an equally efficient architecture for quantum simulation. Lessons from past use of classical analogue computers can help us to build better quantum simulators in future.