We study (1+1)-dimensional O(3) nonlinear sigma model using the tensor renormalization group method with the infinite limit of the bond dimension
Dcut→∞. At the vanishing chemical potential
μ=0, we investigate the von Neumann and Rényi types of entanglement entropies. The central charge is determined to be
c=1.97(9) by using the asymptotic scaling properties of the entropies. We also examine the consistency between two entropies. In the finite density region with
μ=0, where this model suffers from the sign problem in the standard Monte Carlo approach, we investigate the properties of the quantum phase transition. We determine the transition point
μc and the critical exponent of the correlation length
ν from the
μ dependence of the number density in the thermodynamic limit. The dynamical critical exponent
z is also extracted from the scaling behavior of the temporal correlation length as a function of
μ. This is the first successful calculation of the dynamical critical exponent with the TRG method.
We study (1+1)-dimensional O(3) nonlinear sigma model using the tensor renormalization group method with the infinite limit of the bond dimension
Dcut→∞. At the vanishing chemical potential
μ=0, we investigate the von Neumann and R\'enyi types of entanglement entropies. The central charge is determined to be
c=1.97(9) by using the asymptotic scaling properties of the entropies. We also examine the consistency between two entropies. In the finite density region with
μ=0, where this model suffers from the sign problem in the standard Monte Carlo approach, we investigate the properties of the quantum phase transition. We determine the transition point
μc and the critical exponent of the correlation length
ν from the
μ dependence of the number density in the thermodynamic limit. The dynamical critical exponent
z is also extracted from the scaling behavior of the temporal correlation length as a function of
μ. This is the first successful calculation of the dynamical critical exponent with the TRG method.
A bstract We study the quantum phase transition of the (1+1)-dimensional O(3) nonlinear sigma model at finite density using the tensor renormalization group method. This model suffers from the sign problem, which has prevented us from investigating the properties of the phase transition. We investigate the properties of the phase transition by changing the chemical potential μ at a fixed coupling of β . We determine the transition point μ c and the critical exponent ν from the μ dependence of the number density in the thermodynamic limit. The dynamical critical exponent z is also extracted from the scaling behavior of the temporal correlation length as a function of μ .
We numerically study the spectral properties, the entanglement and the zero-temperature phase structure at nonvanishing chemical potential of the O(3) nonlinear sigma model. Using matrix product states, a particular kind of one-dimensional tensor network state, we show that we are able to reach the asymptotic scaling regime and to reproduce the analytical predictions for the mass gap at vanishing chemical potential. In addition, we study the scaling of the entanglement entropy towards the continuum limit obtaining a central charge consistent with 2. Moreover, our approach does not suffer from the sign problem and we also explore the phase structure of the model for nonzero chemical potential and map out the location of the transitions between different charge sectors with high precision.
We study the quantum phase transition of the (1+1)-dimensional O(3) nonlinear sigma model at finite density using the tensor renormalization group method. This model suffers from the sign problem, which has prevented us from investigating the properties of the phase transition. We investigate the properties of the phase transition by changing the chemical potential mu at a fixed coupling of beta. We determine the transition point mu c and the critical exponent nu from the mu dependence of the number density in the thermodynamic limit. The dynamical critical exponent z is also extracted from the scaling behavior of the temporal correlation length as a function of mu.
We report on tensor renormalization group calculations of entanglement entropy in one-dimensional quantum systems. The reduced density matrix of a Gibbs state can be represented as a
1+1-dimensional tensor network, which is analogous to the tensor network representation of the partition function. The HOTRG method is used to approximate the reduced density matrix for arbitrary subsystem sizes, from which we obtain the entanglement entropy. We test our method in the quantum Ising model and obtain the entanglement entropy of the ground state by taking the size of time direction to infinity. The central charge
c is obtained as
c=0.49997(8) for a bond dimension
Dcut=96, which agrees with the theoretical value
c=1/2 within the error.