Fast driven quantum systems: interaction picture and boundary conditions

2021 ◽  
Vol 96 (12) ◽  
pp. 125106
Author(s):  
Nikolay P Tretyakov
Keyword(s):  
Boundary Conditions ◽  
Quantum Systems ◽  
Interaction Picture

scholarly journals Entanglement in Finite Quantum Systems Under Twisted Boundary Conditions

2018 ◽  
Vol 48 (5) ◽  
pp. 451-466
Author(s):  
Krissia Zawadzki ◽  
Irene D’Amico ◽  
Luiz N. Oliveira
Keyword(s):  
Boundary Conditions ◽  
Quantum Systems ◽  
Finite Quantum Systems ◽  
Twisted Boundary Conditions

scholarly journals QUANTUM FORCE DUE TO DISTINCT BOUNDARY CONDITIONS

2003 ◽  
Vol 18 (40) ◽  
pp. 2863-2871 ◽  
Author(s):  
TAMÁS FÜLÖP ◽  
HITOSHI MIYAZAKI ◽  
IZUMI TSUTSUI
Keyword(s):  
Boundary Conditions ◽  
Quantum Systems ◽  
Fixed Number ◽  
Zero Temperature ◽  
Partition Wall ◽  
One Dimensional ◽  
Physical Effects ◽  
Distinct Boundary ◽  
Quantum Force ◽  
Two Sides

We calculate the quantum statistical force acting on a partition wall that divides a one-dimensional box into two halves. The two half boxes containing the same (fixed) number of noninteracting bosons are kept at the same temperature, and admit the same boundary conditions at the outer walls; the only difference is the distinct boundary conditions imposed at the two sides of the partition wall. The net force acting on the partition wall is nonzero at zero temperature and remains almost constant for low temperatures. As the temperature increases, the force starts to decrease considerably, but after reaching a minimum it starts to increase, and tends to infinity with a square-root-of-temperature asympotics. This example demonstrates clearly that distinct boundary conditions cause remarkable physical effects for quantum systems.

scholarly journals Irreversibility in quantum mechanics

2004 ◽  
Vol 2004 (1) ◽  
pp. 75-83 ◽  
Author(s):  
R. C. Bishop ◽  
A. Bohm ◽  
M. Gadella
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Boundary Conditions ◽  
Liouville Equation ◽  
Quantum Systems ◽  
Arrow Of Time ◽  
Time Asymmetry ◽  
Classical Physics ◽  
Von Neumann ◽  
Signal Features

Time asymmetry and irreversibility are signal features of our world. They are the reason of our aging and the basis for our belief that effects are preceded by causes. These features have many manifestations called arrows of time. In classical physics, some of these arrows are described by the increase of entropy or probability, and others by time-asymmetric boundary conditions of time-symmetric equations (e.g., Maxwell or Einstein). However, there is some controversy over whether probability or boundary conditions are more fundamental. For quantum systems, entropy increase is usually associated with the effects of an environment or measurement apparatus on a quantum system and is described by the von Neumann-Liouville equation. But since the traditional (von Neumann) axioms of quantum mechanics do not allow time-asymmetric boundary conditions for the dynamical differential equations (Schrödinger or Heisenberg), there is no quantum analogue of the radiation arrow of time. In this paper, we review consequences of a modification of a fundamental axiom of quantum mechanics. The new quantum theory is time asymmetric and accommodates an irreversible time evolution of isolated quantum systems.

scholarly journals Efficient MPS Algorithm for Periodic Boundary Conditions and Applications Section: Solid matter Original Author's Text: English Abstract: We present the 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 (MPS) and a similar representation for Hamiltonians and other operators (MPO). It is significantly more efficient for systems of about 100 sites and more than for small quantum systems. We apply the formalism to calculate the ground state and the first excited state of a spin-1 Heisenberg ring and deduce the size of a Haldane gap. The results are compared to previous high-precision DMRG calculations. Furthermore, we study the spin-1 systems with a biquadratic nearest-neighbor interaction and show the first results of an application to a mesoscopic Hubbard ring of spinless fermions, which carries a persistent current. Key words: matrix product representation for quantum states (MPS) and Hamiltonians (MPO), spin-1 Heisenberg ring, density matrix renormalization group (DMRG). List Issues Configure

2013 ◽  
Vol 58 (7) ◽  
pp. 657-665 ◽  
Author(s):  
M. Weyrauch ◽  
◽  
M.V. Rakov ◽  
Keyword(s):  
Boundary Conditions ◽  
Periodic Boundary ◽  
Nearest Neighbor ◽  
Periodic Boundary Conditions ◽  
Quantum Systems ◽  
Quantum States ◽  
Matrix Product ◽  
Product Representation ◽  
Density Matrix Renormalization ◽  
Small Quantum
Sign in / Sign up

Export Citation Format

Share Document