Abstract
Quantum multicritical points (QMCPs) emerge at the junction of two or more quantum phase transitions due to the interplay of disparate fluctuations, leading to novel universality classes. While quantum critical points have been well characterized, our understanding of QMCPs is much more limited, even though they might be less elusive to study experimentally than quantum critical points. Here, we characterize the QMCP of an interacting heterogeneous quantum system in two and three dimensions, the ferromagnetic random transverse-field Ising model (RTIM). The QMCP of the RTIM emerges due to both geometric and quantum fluctuations, studied here numerically by the strong disorder renormalization group method. The QMCP of the RTIM is found to exhibit ultraslow, activated dynamic scaling, governed by an infinite disorder fixed point. This ensures that the obtained multicritical exponents tend to the exact values at large scales, while also being universal---i.e., independent of the form of disorder---providing a solid theoretical basis for future experiments.
Highlights
Understanding emergent, collective phenomena in interacting quantum systems is among the fundamental problems of modern physics, with applications in solid-state physics, quantum field-theory, quantum information, and statistical mechanics [1]
We extend the investigations about the critical behavior of the random transverse-field Ising model (RTIM) into the quantum multicritical points (QMCPs), where both geometric and quantum fluctuations diverge
Our strong disorder renormalization group (SDRG) results indicate that the quantum multicritical behavior of the RTIM in two and three dimensions shows ultraslow, activated dynamic scaling, controlled by infinite disorder fixed point (IDFP)
Summary
Understanding emergent, collective phenomena in interacting quantum systems is among the fundamental problems of modern physics, with applications in solid-state physics, quantum field-theory, quantum information, and statistical mechanics [1]. In higher dimensions, the RTIM undergoes a percolation QCP by tuning the bond percolation probability p, for sufficiently weak external fields [14,36] This percolation transition happens at the well-known classical bond percolation critical point pc, independently from the strength of the h external field. For p > pc, at least one giant percolating cluster is present in the system, providing the basis of a generic quantum phase transition by tuning the external field h to its critical value (which depends on p). Both along the percolation and the generic QCPs, the IDFP scenario leads to anomalous, activated dynamic scaling.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
