arXiv subjects

Sei Suzuki

Publications and source records attributed to Sei Suzuki.

23 records · Page 2Linked to original sources

arXiv2007

Quantum annealing of the random-field Ising model by transverse ferromagnetic interactions

We introduce transverse ferromagnetic interactions, in addition to a simple transverse field, to quantum annealing of the random-field Ising model to accelerate convergence toward the target ground state. The conventional approach using only the transverse-field term is known to be plagued by slow convergence when the true ground state has strong ferromagnetic characteristics for the random-field Ising model. The transverse ferromagnetic interactions are shown to improve the performance significantly in such cases. This conclusion is drawn from the analyses of the energy eigenvalues of instantaneous stationary states as well as by the very fast algorithm of Bethe-type mean-field annealing adopted to quantum systems. The present study highlights the importance of a flexible choice of the type of quantum fluctuations to achieve the best possible performance in quantum annealing. The existence of such flexibility is an outstanding advantage of quantum annealing over simulated annealing.

quant-ph↗

arXiv2005

Residual Energies after Slow Quantum Annealing

Features of the residual energy after the quantum annealing are investigated. The quantum annealing method exploits quantum fluctuations to search the ground state of classical disordered Hamiltonian. If the quantum fluctuation is reduced sufficiently slowly and linearly by the time, the residual energy after the quantum annealing falls as the inverse square of the annealing time. We show this feature of the residual energy by numerical calculations for small-sized systems and derive it on the basis of the quantum adiabatic theorem.

cond-mat.dis-nn↗

arXiv2004

Quantum Monte-Carlo method without negative-sign problem for two-dimensional electron systems under strong magnetic fields

The quantum Monte-Carlo method is applied to two-dimensional electron systems under strong magnetic fields. The negative-sign problem involved by this method can be avoided for certain filling factors by modifying interaction parameters from those of the Coulomb interaction. Our techniques for obtaining sign-problem-free parameters are described in detail. Calculated results on static observables are also reported for Landau level filling $ν= 1/3$.

cond-mat.mes-hall↗

arXiv2003

Formulation and Application of Quantum Monte Carlo Method to Fractional Quantum Hall Systems

Quantum Monte Carlo method is applied to fractional quantum Hall systems. The use of the linear programming method enables us to avoid the negative-sign problem in the Quantum Monte Carlo calculations. The formulation of this method and the technique for avoiding the sign problem are described. Some numerical results on static physical quantities are also reported.

cond-mat.mes-hall↗

arXiv2000

Transition between Compressible and Incompressible States in Infinite-Layer Fractional Quantum Hall Systems

Possible phase transitions between incompressible quantum Hall states and compressible three-dimensional states are discussed for infinite-layer electron systems in strong magnetic field. By variational Monte Carlo calculation, relative stability of some trial states is studied. If the inter-layer distance is large enough, the Laughlin state is stabilized for the Landau-level filling ν=1/3 of each layer. When the inter-layer distance is comparable to the magnetic length, the Laughlin state becomes unstable against a different fractional quantum Hall state with inter-layer correlation, and/or against a three-dimensional compressible state. It is discussed how the quantum phase transition between them can be controlled in actual systems.

cond-mat.mes-hall↗