Quantum cluster quasicrystals

Abstract

Quasicrystals remain among the most intriguing materials in physics and chemistry. Their structure results in many unusual properties including anomalously low friction as well as poor electrical and thermal conductivity but it also supports superconductivity, which shows that quantum effects in quasicrystals can be quite unique. Here we theoretically study superfluidity in a model quantum cluster quasicrystal. Using path-integral Monte Carlo simulations, we explore a 2D ensemble of bosons with the Lifshitz-Petrich-Gaussian pair potential, finding that moderate quantum fluctuations do not destroy the dodecagonal quasicrystalline order. This quasicrystal is characterized by a small yet finite superfluidity, demonstrating that particle clustering combined with the local cogwheel structure can underpin superfluidity even in the almost classical regime. This type of distributed superfluidity may also be expected in certain open crystalline lattices. Large quantum fluctuations are shown to induce transitions to cluster solids, supersolids and superfluids, which we characterize fully quantum-mechanically.

Zonal Estimators for Quasiperiodic Bosonic Many-Body Phases

“…The same model has also been applied to bosonic systems, where the effects of zero point motion, as well as quantum exchanges, disclose rich phase diagrams including quantum quasicrystal with 12-fold rotational symmetry [ 17 ]. Additionally, quantum properties of self-assembled cluster quasicrystals revealed that, in some cases, quantum fluctuations do not jeopardize dodecagonal structures, showing a small but finite local superfluidity [ 19 ]. Cluster quasicrystals display peculiar features, not exhibited by simpler quasiperiodic structures.…”

“…Cluster quasicrystals display peculiar features, not exhibited by simpler quasiperiodic structures. By increasing quantum fluctuations, in fact, a structural transition from quasicrystal to cluster triangular crystal featuring the properties of a supersolid is observed [ 19 , 66 , 67 ]. We point out that the discussed methodology is also useful to analyze the superfluid character of further peculiar inhomogeneous systems such as, for instance, bosons enclosed within spherical traps or subject to a polyhedral-symmetric substrate potential [ 68 , 69 , 70 ].…”

“…Over the last thirty years, this has been amply demonstrated on quantum fluids [ 2 , 3 , 4 ] and, more recently, in ultra-cold gases like, for instance, dipolar systems [ 5 , 6 , 7 , 8 , 9 ] and Rydberg atoms [ 10 , 11 , 12 , 13 ]. For strongly-interacting quantum fluids, there is at present considerable interest towards the exploration of patterns owing to peculiar symmetries such as quantum-cluster crystals [ 14 , 15 ], stripe phases [ 16 ], or cluster quasicrystals [ 17 , 18 , 19 ], with the aim of understanding fundamental physical phenomena. In this regard, also thanks to the increase in computational capabilities, advancements in PIMC methods continue to play a key role.…”

Cluster stability driven by quantum fluctuations

“…Quantum aspects of quasicrystals with a dodecagonal symmetry have been newly discussed in Ref. [23]. In particular, the authors observed that a quantum quasicrystal still maintains the dodecagonal pattern as well as a small yet finite superfluidity signal.…”

Thermal and Quantum Fluctuation Effects in Quasiperiodic Systems in External Potentials

“…In this work we study the many-body phases for an ensemble of distinguishable particles interacting via a Lifshitz-Petrich-Gaussian pair potential in the presence of an external trapping potential. Extensive analysis of the phases has been done in the classical regime [32,33], and more recently also in the quantum limit [34]. Examples of phases for these potentials include various types of quasicrystalline order and stripe phases.…”