Instytut Fizyki Uniwersytetu Jagiellonskiego

Kraków, Poland

Instytut Fizyki Uniwersytetu Jagiellonskiego

Kraków, Poland
SEARCH FILTERS
Time filter
Source Type

Gardas B.,Los Alamos National Laboratory | Gardas B.,University of Silesia | Dziarmaga J.,Instytut Fizyki Uniwersytetu Jagiellonskiego | Zurek W.H.,Los Alamos National Laboratory
Physical Review B - Condensed Matter and Materials Physics | Year: 2017

The ground state of the one-dimensional Bose-Hubbard model at unit filling undergoes the Mott-superfluid quantum phase transition. It belongs to the Kosterlitz-Thouless universality class with an exponential divergence of the correlation length in place of the usual power law. We present numerical simulations of a linear quench both from the Mott insulator to superfluid and back. The results satisfy the scaling hypothesis that follows from the Kibble-Zurek mechanism (KZM). In the superfluid-to-Mott quenches there is no significant excitation in the superfluid phase despite its gaplessness. Since all critical superfluid ground states are qualitatively similar, the excitation begins to build up only after crossing the critical point when the ground state begins to change fundamentally. The last process falls into the KZM framework. © 2017 American Physical Society.


Francuz A.,Instytut Fizyki Uniwersytetu Jagiellonskiego | Francuz A.,Los Alamos National Laboratory | Dziarmaga J.,Instytut Fizyki Uniwersytetu Jagiellonskiego | Gardas B.,Los Alamos National Laboratory | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2016

When a system is driven across a quantum critical point at a constant rate, its evolution must become nonadiabatic as the relaxation time τ diverges at the critical point. According to the Kibble-Zurek mechanism (KZM), the emerging post-transition excited state is characterized by a finite correlation length ξ set at the time t=τ when the critical slowing down makes it impossible for the system to relax to the equilibrium defined by changing parameters. This observation naturally suggests a dynamical scaling similar to renormalization familiar from the equilibrium critical phenomena. We provide evidence for such KZM-inspired spatiotemporal scaling by investigating an exact solution of the transverse field quantum Ising chain in the thermodynamic limit. © 2016 American Physical Society.


Swislocki T.,Instytut Fizyki PAN | Witkowska E.,Instytut Fizyki PAN | Dziarmaga J.,Instytut Fizyki Uniwersytetu Jagiellonskiego | Matuszewski M.,Instytut Fizyki PAN
Physical Review Letters | Year: 2013

We consider a phase transition from an antiferromagnetic to a phase separated ground state in a spin-1 Bose-Einstein condensate of ultracold atoms. We demonstrate the occurrence of two scaling laws, for the number of spin domain seeds just after the phase transition, and for the number of spin domains in the final, stable configuration. Only the first scaling can be explained by the standard Kibble-Zurek mechanism. We explain the occurrence of two scaling laws by a model including postselection of spin domains due to the conservation of condensate magnetization. © 2013 American Physical Society.


Witkowska E.,Instytut Fizyki PAN | Dziarmaga J.,Instytut Fizyki Uniwersytetu Jagiellonskiego | Swislocki T.,Instytut Fizyki PAN | Matuszewski M.,Instytut Fizyki PAN
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We investigate the dynamics and outcome of a quantum phase transition from an antiferromagnetic to a phase-separated ground state in a spin-1 Bose-Einstein condensate of ultracold atoms. We explicitly demonstrate double universality in the dynamics within experiments with various quench times. Furthermore, we show that spin domains created in the nonequilibrium transition constitute a set of mutually incoherent quasicondensates. The quasicondensates appear to be positioned in a semiregular fashion, which is a result of the conservation of local magnetization during the postselection dynamics. © 2013 American Physical Society.


PubMed | Instytut Fizyki Uniwersytetu Jagiellonskiego and Instytut Fizyki PAN
Type: Journal Article | Journal: Physical review letters | Year: 2014

We consider a phase transition from an antiferromagnetic to a phase separated ground state in a spin-1 Bose-Einstein condensate of ultracold atoms. We demonstrate the occurrence of two scaling laws, for the number of spin domain seeds just after the phase transition, and for the number of spin domains in the final, stable configuration. Only the first scaling can be explained by the standard Kibble-urek mechanism. We explain the occurrence of two scaling laws by a model including postselection of spin domains due to the conservation of condensate magnetization.


Czarnik P.,Instytut Fizyki Uniwersytetu Jagiellonskiego | Dziarmaga J.,Instytut Fizyki Uniwersytetu Jagiellonskiego
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

A projected entangled pair state (PEPS) with ancillas can be evolved in imaginary time to obtain thermal states of a strongly correlated quantum system on a two-dimensional lattice. Every application of a Suzuki-Trotter gate multiplies the PEPS bond dimension D by a factor k. It has to be renormalized back to the original D. In order to preserve the accuracy of the Suzuki-Trotter (ST) decomposition, the renormalization in principle has to take into account full environment made of the new tensors with the bond dimension k x D. Here, we propose a self-consistent renormalization procedure operating with the original bond dimension D, but without compromising the accuracy of the ST decomposition. The iterative procedure renormalizes the bond using full environment made of renormalized tensors with the bond dimension D. After every renormalization, the new renormalized tensors are used to update the environment, and then the renormalization is repeated again and again until convergence. As a benchmark application, we obtain thermal states of the transverse field quantum Ising model on a square lattice, both infinite and finite, evolving the system across a second-order phase transition at finite temperature. ©2015 American Physical Society.


Czarnik P.,Instytut Fizyki Uniwersytetu Jagiellonskiego | Dziarmaga J.,Instytut Fizyki Uniwersytetu Jagiellonskiego
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

The projected entangled pair state (PEPS) ansatz can represent a thermal state in a strongly correlated system. We introduce a variational algorithm to optimize this tensor network whose essential ingredient is an auxiliary tree tensor network (TTN). Since the full tensor environment is taken into account, with increasing bond dimension the PEPS-TTN ansatz provides the exact Gibbs state. Our presentation opens with a 1D version for a matrix product state (MPS-TTN) and then generalizes to PEPS-TTN in 2D. Benchmark results in the quantum Ising model are presented. © 2015 American Physical Society.


Czarnik P.,Instytut Fizyki Uniwersytetu Jagiellonskiego | Dziarmaga J.,Instytut Fizyki Uniwersytetu Jagiellonskiego
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

We introduce a spin-orbital entangled (SOE) resonating valence bond (RVB) state on a square lattice of spins 12 and orbitals represented by pseudospins 12. Like the standard RVB state, it is a superposition of nearest-neighbor hard-core coverings of the lattice by spin singlets, but adjacent singlets are favored to have perpendicular orientations and, more importantly, an orientation of each singlet is entangled with orbitals state on its two lattice sites. The SOE-RVB state can be represented by a projected entangled pair state (PEPS) with a bond dimension D=4. This representation helps to reveal that the state is a superposition of striped coverings conserving a topological quantum number. The stripes are a critical quantum spin liquid. We propose a spin-orbital Hamiltonian supporting a SOE-RVB ground state. © 2015 American Physical Society.

Loading Instytut Fizyki Uniwersytetu Jagiellonskiego collaborators
Loading Instytut Fizyki Uniwersytetu Jagiellonskiego collaborators