Adiabatic quantum computation along quasienergies

TL;DR

This paper explores a novel approach to quantum adiabatic algorithms using quasienergies of unitary operators, enabling discrete adiabatic passage and potential advantages in quantum search problems.

Contribution

It introduces a new design principle for adiabatic quantum computation along quasienergies, including the use of anholonomies and a parameter |v> to control computational gaps and efficiency.

Findings

Quasienergy-based adiabatic algorithms can be realized via parameterized quantum circuits.

Adjusting the parameter |v> influences the computational cost and efficiency.

The approach offers qualitative differences in resource requirements for different running times.

Abstract

The parametric deformations of quasienergies and eigenvectors of unitary operators are applied to the design of quantum adiabatic algorithms. The conventional, standard adiabatic quantum computation proceeds along eigenenergies of parameter-dependent Hamiltonians. By contrast, discrete adiabatic computation utilizes adiabatic passage along the quasienergies of parameter-dependent unitary operators. For example, such computation can be realized by a concatenation of parameterized quantum circuits, with an adiabatic though inevitably discrete change of the parameter. A design principle of adiabatic passage along quasienergy is recently proposed: Cheon's quasienergy and eigenspace anholonomies on unitary operators is available to realize anholonomic adiabatic algorithms [Tanaka and Miyamoto, Phys. Rev. Lett. 98, 160407 (2007)], which compose a nontrivial family of discrete adiabatic algorithms. It is straightforward to port a standard adiabatic algorithm to an anholonomic adiabatic one, except an introduction of a parameter |v>, which is available to adjust the gaps of the quasienergies to control the running time steps. In Grover's database search problem, the costs to prepare |v> for the qualitatively different, i.e., power or exponential, running time steps are shown to be qualitatively different. Curiously, in establishing the equivalence between the standard quantum computation based on the circuit model and the anholonomic adiabatic quantum computation model, it is shown that the cost for |v> to enlarge the gaps of the eigenvalue is qualitatively negligible.