Quantum critical dynamics simulation of dirty boson systems

Area of Science:

• Condensed Matter Physics
• Quantum Phase Transitions
• Disordered Systems

Background:

• The dynamic critical exponent (z) at the Bose glass to superfluid quantum phase transition is crucial for understanding critical phenomena.
• Previous theoretical and numerical studies suggested z=d (where d is the spatial dimension), but this result has been recently challenged.

Purpose of the Study:

• To rigorously evaluate the critical exponents, particularly z, for the 2D Bose glass to superfluid quantum phase transition.
• To determine the accurate value of z and assess whether the previously proposed z=d scaling holds.

Main Methods:

• Utilized highly effective worm Monte Carlo simulations for a 2D model of quantum bosons at zero temperature with disorder.
• Employed a finite-size scaling analysis approach.
• Focused on determining the scaling of the quantum correlation time from boson world line simulation data.

Main Results:

• Calculated critical exponents: z=1.8±0.05, ν=1.15±0.03, and η=-0.3±0.1.
• The obtained value for z (1.8±0.05) deviates significantly from the expected z=2 (since d=2).

Conclusions:

• The results indicate that the dynamic critical exponent z=2 is not satisfied for the 2D Bose glass to superfluid quantum phase transition.
• This study provides strong evidence against the long-standing theoretical prediction of z=d in this context.