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In a previous paper [quant-ph/0408045] we described a quantum algorithm to prepare an arbitrary state of a quantum register with arbitrary fidelity. Here we present an alternative algorithm which uses a small number of quantum oracles…

Quantum Physics · Physics 2009-11-10 Andrei N. Soklakov , Ruediger Schack

We propose an algorithm for computing real-time observables using a quantum processor while avoiding the need to prepare the full quantum state. This reduction in quantum resources is achieved by classically sampling configurations in…

High Energy Physics - Lattice · Physics 2020-01-31 Siddhartha Harmalkar , Henry Lamm , Scott Lawrence

The semivarying coefficient models are widely used in the application of finance, economics, medical science and many other areas. The functional coefficients are commonly estimated by local smoothing methods, e.g. local linear estimator.…

Methodology · Statistics 2020-01-01 Heng Peng , Chuanlong Xie , Jingxin Zhao

The center of mass motion of trapped ions and neutral atoms is suitable for approximation by a time-dependent driven quantum harmonic oscillator whose frequency and driving strength may be controlled with high precision. We show the time…

Quantum Physics · Physics 2024-03-25 E. García Herrera , F. Torres-Leal , B. M. Rodríguez-Lara

Phonon frequencies at Gamma-point in non-magnetic rhombohedral phase of LaCoO3 were calculated using density functional theory (DFT) with hybrid exchange correlation functional PBE0. The calculations involved a comparison of results for two…

Materials Science · Physics 2015-05-19 Denis Gryaznov , Robert A. Evarestov , Joachim Maier

We present a rigorous and efficient approach to the calculation of classical lattice-dynamical quantities from simulations that do not require an explicit solution of the time evolution. We focus on the temperature-dependent vibrational…

Materials Science · Physics 2013-03-14 Mathias P. Ljungberg , Jorge Íñiguez

The traditional picture of heat transfer in solids by atomic vibrations, also known as phonons, involves phonons scattering with each other like gas particles and is commonly referred to as the phonon gas model (PGM). This physical picture…

Materials Science · Physics 2021-08-11 Andrew Rohskopf , Ruiyang Li , Tengfei Luo , Asegun Henry

A low complexity frequency offset estimation algorithm based on all-phase FFT for M-QAM is proposed. Compared with two-stage algorithms such as FFT+CZT and FFT+ZoomFFT, our algorithm can lower computational complexity by 73% and 30%…

Signal Processing · Electrical Eng. & Systems 2021-05-24 Qian Li

We present an implementation of an efficient algorithm for the calculation of the spectrum of one-dimensional quantum systems with periodic boundary conditions. This algorithm is based on a matrix product representation for quantum states…

Statistical Mechanics · Physics 2016-12-05 Michael Weyrauch , Mykhailo V. Rakov

A scheme for fine tuning of quantum operations to improve their performance is proposed. A quantum system in $\Lambda$ configuration with two-photon Raman transitions is considered without adiabatic elimination of the excited (intermediate)…

Quantum Physics · Physics 2008-03-10 Grzegorz Chimczak , Ryszard Tanaś

We propose an implementation of the algorithm for the fast Fourier transform (FFT) as a quantum circuit consisting of a combination of some quantum gates. In our implementation, a data sequence is expressed by a tensor product of vector…

Quantum Physics · Physics 2020-08-11 Ryo Asaka , Kazumitsu Sakai , Ryoko Yahagi

Electronic susceptibilities are a very popular tool to study electronic and magnetic properties of materials, both in experiment and theory. Unfortunately, the numerical evaluation of even the bare susceptibility, which depends on the…

Superconductivity · Physics 2014-09-29 Christoph Heil , Heinrich Sormann , Lilia Boeri , Markus Aichhorn , Wolfgang von der Linden

The ground state of an homogeneous electron gas is a paradigmatic state that has been used to model and predict the electronic structure of matter at equilibrium for nearly a century. For half a century, it has been successfully used to…

Chemical Physics · Physics 2024-06-11 Tim Gould , Stefano Pittalis

Quantum phase estimation plays a central role in quantum simulation as it enables the study of spectral properties of many-body quantum systems. Most variants of the phase estimation algorithm require the application of the global unitary…

The accuracy of rate constants calculated using transition state theory depends crucially on the correct identification of a recrossing--free dividing surface. We show here that it is possible to define such optimal dividing surface in…

We propose an efficient method to compute reaction rate constants of thermally activated processes occurring in many-body systems at finite temperature. The method consists in two steps: first, paths are sampled using a transition path…

Statistical Mechanics · Physics 2011-12-22 Massimiliano Picciani

Preparing the ground state of a system is an important task in physics. We propose a quantum algorithm for preparing the ground state of a physical system that can be simulated on a quantum computer. The system is coupled to an ancillary…

Quantum Physics · Physics 2018-05-14 Hefeng Wang

The Fourier spectrum at a fractional period is often examined when extracting features from biological sequences and time series. It reflects the inner information structure of the sequences. A fractional period is not uncommon in time…

Spectral Theory · Mathematics 2017-11-03 Jiasong Wang , Changchuan Yin

Charge and energy transfer in biological and synthetic organic materials are strongly influenced by the coupling of electronic states to high-frequency underdamped vibrations under dephasing noise. Non-perturbative simulations of these…

Quantum Physics · Physics 2019-09-05 Alejandro D. Somoza , Oliver Marty , James Lim , Susana F. Huelga , Martin B. Plenio

The calculation of material phonon thermal conductivity from density functional theory calculations requires computationally expensive evaluation of anharmonic interatomic force constants and has remained a computational bottleneck in the…

Materials Science · Physics 2024-09-04 Yagyank Srivastava , Ankit Jain