The Dynamics of Quantum Computing in Molecules

Neil Gershenfeld, Isaac L. Chuang

康 近藤, 幹夫 中原, 和也 畑 +1 more

A Hamiltonian in the rotating frame is derived for NMR quantum computing with homonucleus molecules as its computational resource. It is theoretically shown that control pulses designed for heteronucleus spins can be translated to pulses for homonucleus spins by simply replacing hard pulses by soft pulses with properly chosen pulse width. Several experiments employing cytosine as a homonucleus molecule are conducted and it is proved experimentally that the above Hamiltonian accurately describes the dynamics of the spins.

Alexander M. Dalzell, Sam McArdle, Mario Berta +10 more

This chapter covers applications of quantum computing in the area of quantum chemistry, where the goal is to predict the physical properties and behaviors of atoms, molecules, and materials. We discuss algorithms for simulating electrons in molecules and materials, including both static properties such as ground state energies and dynamic properties. We also discuss algorithms for simulating static and dynamic aspects of vibrations in molecules and materials.

Harshdeep Singh, Sonjoy Majumder, Sabyashachi Mishra

Harshdeep Singh, Sonjoy Majumder, Sabyashachi Mishra

Fabian Langkabel, Annika Bande

In this work, we investigate the capability of known quantum-computing algorithms for fault-tolerant quantum computing to simulate the laser-driven electron dynamics in small molecules such as lithium hydride. These computations are executed on a quantum-computer simulator. Results are compared with the time-dependent full configuration interaction method (TD-FCI). The actual wave packet propagation is closely reproduced using the Jordan-Wigner transformation and the Trotter product formula. In addition, the time-dependent dipole moment, as an example of a time-dependent expectation value, is calculated using the Hadamard test. In order to include non-Hermitian operators in the dynamics, a similar approach to the quantum imaginary time evolution (QITE) algorithm is employed to translate the propagator into quantum gates. Thus, ionization of a hydrogen molecule under the influence of a complex absorbing potential can be simulated accurately. All quantum computer algorithms used scale polynomially rather than exponentially as TD-FCI and therefore hold promise for substantial progress in the understanding of electron dynamics of increasingly large molecular systems in the future.